REMOVAL OF ZINC, NICKEL

REMOVAL OF ZINC, NICKEL
A Thesis on
REMOVAL OF ZINC, NICKEL AND COPPER
IONS FROM WASTE WATER USING CHARA SPONGE IRON PLANT WASTE
Submitted by
DEEPTHI TIRUMALARAJU
(609ch303)
For the partial fulfillment of
M.Tech by Research Degree
Under Esteemed guidance of
DR. SUSMITA MISHRA
Aug-2011
Department of Chemical Engineering
National Institute of Technology
Rourkela, Orissa
DEPARTMENT OF CHEMICAL ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY, ROURKELA
ORISSA, INDIA - 769008
CERTIFICATE
This is to certify that the thesis titled “Removal of Zinc, Nickel and Copper ions from
Waste Water using char - A Sponge Iron Plant Waste”, submitted to the National Institute of
Technology, Rourkela by Miss. Deepthi Tirumalaraju, Roll No. 609CH303 for the award of
the degree of Master of Technology (Research) in Chemical Engineering, is a bona fide record
of research work carried out by her under my supervision and guidance. The candidate has
fulfilled all the prescribed requirements. The thesis, which is based on candidate‟s own work, has
not been submitted elsewhere for a degree/diploma.
In my opinion, the thesis is of standard required for the award of a Master of Technology
(Research) degree in Chemical Engineering. To the best of my knowledge, she bears a good
moral character and decent behavior.
Dr. Mrs. S. Mishra.
Assistant Professor
Department of Chemical Engineering
National Institute of Technology
Rourkela‐769 008 (INDIA)
Email: [email protected]
i
AKNOWLEDGENT
I would like to take this opportunity to extend my deepest gratitude to my teacher and
supervisor, Prof. Susmita Mishra, for her continuous encouragement and active guidance. I am
indebted to her for the valuable time she has spared for me during this work. She is always there
to meet and talk about my ideas, to proofread and mark up my research papers and chapters, and
to ask me good questions to help me think through my problems.
I am very much thankful to Prof. R.K. Singh, Head, Department of Chemical
Engineering, for his continuous encouragement. Also, I am indebted to him who provided me all
official and laboratory facilities.
I am grateful to Prof. Mrs, K. K. Paul, Civil Engineering Department, N.I.T Rourkela for
allowing me to utilize the AAS facility in their department.
My sincere thanks to Prof. G.K. Roy, and Dr. M. Kundu whose valuable suggestions
helped me a lot in completing my project. My sincere thanks go to Dr. S. Khannam, Dr. S. Paria
and Dr. A. Sahoo, who taught me valuable subjects, which helped me a lot in completing this
thesis. I would like to thank RSP (Rourkela Steel Plant) for providing me the adsorbent material.
In addition, let me thank all my friends Ramakrishna sir, Divya, Gautami, Vamsi,
Vikranth, Tapaswini and Deba Laxmi for their great support and encouragement during the
research period. Also, I am thankful to all the non-teaching staffs of Chemical Engineering
Department for their kind cooperation.
My special thanks to my friends Abhipsa and Chaitanya for helping me and standing by
me throughout the project in every aspect.
Last but not the least; I take this opportunity to express my regards and obligation to my
parents and family members for educating me in all aspects. I can never forget for their
unconditional support and encouragement to pursue my interests.
Deepthi…
ii
CONTENTS
CERTIFICATE .............................................................................................................................. i
ACKNOWLEDGENT .................................................................................................................. ii
Contents ........................................................................................................................................ iii
List of Tables ............................................................................................................................... vii
List of Figures............................................................................................................................. viii
Abstract .......................................................................................................................................... x
1
INTRODUCTION .................................................................................................................. 1
1.1 Introduction ......................................................................................................................... 1
1.1.1 Objective ........................................................................................................................ 3
2
LITERATURE REVIEW ...................................................................................................... 5
2.1 Zinc ....................................................................................................................................... 5
2.1.1 Importance of Zinc ......................................................................................................... 5
2.1.2 Harmful effects of zinc ................................................................................................... 6
2.1.3 Sources of Zinc pollution ............................................................................................... 7
2.1.3.1 Industrial sources ..................................................................................................... 7
2.1.3.2 Domestic sources ..................................................................................................... 7
2.1.4 Different techniques for zinc treatment .......................................................................... 7
2.1.4.1 Chemical precipitation ............................................................................................. 8
2.1.4.2 Ion –exchange .......................................................................................................... 8
2.1.4.3 Membrane filtration ................................................................................................. 9
2.1.4.4 Electrochemical methods ......................................................................................... 9
2.1.4.5 Biological methods ................................................................................................ 10
2.1.4.6 Adsorption methods ............................................................................................... 11
2.2 Nickel .................................................................................................................................. 15
2.2.1 Importance of Nickel .................................................................................................... 15
2.2.2 Harmful effects of Nickel ............................................................................................. 16
2.2.3 Sources of Nickel pollution .......................................................................................... 17
2.2.4 Different techniques for Nickel removal ...................................................................... 17
iii
2.2.4.1
2.2.4.2
2.2.4.3
2.2.4.4
2.2.4.5
2.2.4.6
Chemical precipitation ........................................................................................... 18
Ion- exchange ........................................................................................................ 18
Membrane filtration ............................................................................................... 19
Electrochemical methods ....................................................................................... 19
Biological methods ................................................................................................ 20
Adsorption ............................................................................................................. 20
2.3 Copper................................................................................................................................ 22
2.3.1 Importance of Copper................................................................................................... 22
2.3.2 Harmful effects of copper ............................................................................................ 23
2.3.3 Sources of Copper Pollution ........................................................................................ 24
2.3.4 Different techniques for Copper removal..................................................................... 24
2.3.4.1 Chemical precipitation ........................................................................................... 25
2.3.4.2 Ion-exchange ......................................................................................................... 25
2.3.4.3 Membrane filtration ............................................................................................... 26
2.3.4.4 Electrochemical techniques ................................................................................... 27
2.3.4.5 Biological methods ................................................................................................ 27
2.3.4.6 Adsorption ............................................................................................................. 28
2.4
3
3.1
Scope of precent work. ..................................................................................................... 31
MATERIALS AND METHODS ........................................................................................ 32
Preparation of adsorbent ................................................................................................. 32
3.2 Characterization of adsorbent ......................................................................................... 32
3.2.1 Physical parameters ...................................................................................................... 32
3.2.1.1 Moisture analysis ................................................................................................... 32
3.2.1.2 Volatile matter analysis ......................................................................................... 32
3.2.1.3 Ash content analysis .............................................................................................. 33
3.2.1.4 Iodine number ........................................................................................................ 33
3.2.1.5 Analysis of specific surface area ........................................................................... 34
3.2.1.6 Zeta potential ......................................................................................................... 34
3.2.2 Chemical properties...................................................................................................... 34
3.2.2.1 FTIR analysis ......................................................................................................... 34
3.2.2.2 Scanning Electron Microscope (SEM) analysis .................................................... 34
3.3
Chemicals ........................................................................................................................... 35
3.4
Stock solution preparation ............................................................................................... 35
iv
3.5
Instrumentation................................................................................................................. 35
3.6
Adsorption Experiment .................................................................................................... 36
3.7 Adsorption isotherms........................................................................................................ 36
3.7.1 Langmuir isotherm model ............................................................................................ 37
3.7.2 Freundlich isotherm model........................................................................................... 38
3.7.3 Dubinin –Radushkevich isotherm ................................................................................ 39
3.7.4 Temkin isotherm .......................................................................................................... 39
3.8 Adsorption kinetics model ................................................................................................ 40
3.8.1 Pseudo-first order model .............................................................................................. 41
3.8.2 Pseudo-second order model ......................................................................................... 41
3.9
Adsorption mechanism ..................................................................................................... 42
3.10
Thermodynamic parameters ........................................................................................ 42
3.11
Fixed bed adsorption studies ........................................................................................ 43
3.12
Analysis of column data ................................................................................................ 44
3.13
Modeling of Breakthrough curve ................................................................................. 46
3.13.1
Thomas model ........................................................................................................... 46
4
RESULTS AND DISCUSSION- BATCH ADSORPTION .............................................. 47
4.1 Characterization of adsorbent ......................................................................................... 47
4.1.1 Physical properties ....................................................................................................... 47
4.1.2 Chemical properties...................................................................................................... 47
4.1.2.1 FTIR analysis ......................................................................................................... 47
4.1.2.2 Analysis of SIP waste by SEM/EDX .................................................................... 48
4.2 Batch Adsorption studies ................................................................................................. 49
4.2.1 Zinc............................................................................................................................... 49
4.2.1.1 Effect of parameters............................................................................................... 49
4.2.1.2 Adsorption isotherms ............................................................................................. 53
4.2.1.3 Adsorption kinetics ................................................................................................ 55
4.2.1.4 Adsorption mechanism .......................................................................................... 55
4.2.1.5 Thermodynamic study of adsorption process ........................................................ 56
4.2.2 Nickel ........................................................................................................................... 57
4.2.2.1 Effect of parameters............................................................................................... 57
v
4.2.2.2 Adsorption isotherms ............................................................................................. 61
4.2.2.3 Adsorption kinetics: ............................................................................................... 63
4.2.2.4 Adsorption mechanism .......................................................................................... 63
4.2.2.5 Thermodynamic study of adsorption process ........................................................ 64
4.2.3 Copper .......................................................................................................................... 65
4.2.3.1 Effect of parameters............................................................................................... 65
4.2.3.2 Adsorption isotherms ............................................................................................. 68
4.2.3.3 Adsorption Kinetics ............................................................................................... 70
4.2.3.4 Adsorption mechanism .......................................................................................... 71
4.2.3.5 Thermodynamic study of adsorption process ........................................................ 71
4.2.4 Co- adsorption of zinc and nickel ................................................................................ 73
4.2.4.1 Effect of parameters............................................................................................... 73
4.2.4.2 Effect of co-adsorption .......................................................................................... 75
5
RESULTS AND DISCUSSION- COLUMN ADSORPTION .......................................... 77
5.1 Effect of Parameters ......................................................................................................... 77
5.1.1 Effect of bed height ...................................................................................................... 77
5.1.2 Effect of flow rate ........................................................................................................ 78
5.2
Regeneration studies ......................................................................................................... 80
5.3 Modeling of Breakthrough curve .................................................................................... 81
5.3.1 Thomas model .............................................................................................................. 81
6
CONCLUSION ..................................................................................................................... 83
7
BIBLIOGRAPHY ................................................................................................................ 85
vi
LIST OF TABLES
TABLE 3.1: List of Instruments
TABLE 4.1: Characteristics of untreated and HCl treated SIP waste.
TABLE 4.2: Elemental composition of adsorbents.
TABLE 4.3: Isotherm constants of zinc adsorption
TABLE 4.4: Intraparticle rate parameters, external mass transfer and diffusion coefficients
TABLE 4.5: Thermodynamic parameters of zinc adsorption.
TABLE 4.6: Isotherm constants of nickel adsorption on SIP waste.
TABLE 4.7:
Intraparticle rate parameters, external mass transfer and diffusion coefficients
TABLE 4.8: Thermodynamic parameters of nickel adsorption.
TABLE 4.9: Isotherm constants of copper adsorption.
TABLE 4.10: Intraparticle rate parameters, external mass transfer and diffusion coefficients
TABLE 4.11: Thermodynamic parameters of nickel adsorption.
TABLE 4.12: Comparison of adsorption capacities with other adsorbents at standard conditions.
TABLE 5.1: Zinc adsorption data on SIP waste in a fixed bed column at different operating
conditions.
vii
LIST OF FIGURES
Figure 3.1: Fixed bed column used for the column adsorption studies
Figure 4.1: FTIR Spectrum of (a) Untreated SIP waste. (b) HCl treated SIP waste.
Figure 4.2: SEM analysis of (a) untreated and (b) HCl treated SIP Waste.
Figure 4.3: Effect of contact time on zinc adsorption using untreated SIP waste,HCl treated SIP
waste
Figure 4.4: Effect of Adsorbent Dose on Zn adsorption.
Figure 4.5: Effect of pH on percentage removal of zinc on SIP waste.
Figure 4.6: Effect of Initial metal concentration on the rate of adsorption.
Figure 4.7: Effect of temperature on percentage removal of zinc by SIP waste.
Figure 4.8: Langmuir adsorption isotherm for zinc adsorption
Figure 4.9: Frendluich adsorption isotherm for zinc adsorption
Figure 4.10: D-R isotherm model for zinc adsorption
Figure 4.11: Temkin isotherm model for zinc adsorption
Figure 4.12: Pseudo first order kinetics plot for Zinc Adsorption
Figure 4.13: Pseudo second order kinetics plot for zinc adsorption
Figure 4.14: The Vant Hoff‟s plot of ln K vs. 1/T
Figure 4.15: Effect of contact time on adsorption of Nickel ions
Figure 4.16: Effect of Adsorbent Dose on Zn adsorption.
Figure 4.17: Effect of pH on adsorption of Nickel ions
Figure 4.18: Effect of Initial metal concentration on adsorption of Nickel ions
Figure 4.19: Effect of Temperatureon adsorption of Nickel ions
Figure 4.20: Langmuir isotherm model for Nickel adssorption
Figure 4.21: Freundlich isotherm model for Nickel adssorption
Figure 4.22: D-R isotherm model for Nickel adssorption
viii
Figure 4.23: Temkin isotherm model for Nickel adsorption
Figure 4.24: Pseudo first order kinetics plot for nickel adsorption.
Figure 4.25: Pseudo second order kinetics plot for nickel adsorption.
Figure 4.26: Plot of lnk vs. 1/T
Figure 4.27: Effect of contact time on copper removal.
Figure 4.28: Effect of pH on copper removal.
Figure 4.29: Effect of the initial metal concentration on copper adsorption.
Figure 4.30: Effect of temperature on copper removal by SIP waste
Figure 4.31: Langmuir isotherm model for copper removal.
Figure 4.32: Freundlich isotherm model for copper adsorption.
Figure 4.33: D-R isotherm model for copper adsorption.
Figure 4.34: Temkin isotherm model for copper adsorption.
Figure 4.35: Pseudo first order kinetics plot for copper Adsorption
Figure 4.36: Pseudo second order kinetics plot for copper adsorption
Figure 4.37: Plot lnk vs. 1/T
Figure 4.38: Effect of initial metal concentration on adsorption of Zn, Ni ions onto SIP waste.
Figure 4.39: Effect of temperature on Co-adsorption of Zn and Ni ions onto SIP waste.
Figure 4.40: Effect of co-adsorption on the adsorption of individual metal ions on SIP waste.
Figure 5.1: Break through curve for zinc at different bed heights.
Figure 5.2: Break through curve for nickel at different bed heights
Figure 5.3: Break through curves for zinc at different flow rate.
Figure 5.4: Break through curves for nickel at different flow rate.
Figure 5.5: Elution curves for zinc columns using 0.1 N HCl.
Figure 5.6: Elution curves for nickel columns using 0.1 N HCl
ix
ABSTRACT
Adsorption is a well known technology to address water solution problem typically for heavy
metal pollution. Batch studies for individual heavy metals such as Zinc, Copper and Nickel was
investigated using adsorbent, sponge iron plant waste. Surface modification of the adsorbent was
achieved using HCl treatment. Surface characterization using proximate and ultimate analysis
indicated improved in carbon content. FTIR, BET, SEM/ EDX, analysis further confirmed its
surface modification. Batch studies were conducted to explore the influence of various
parameters such as initial solution pH, adsorbent dosage, contact time, temperature etc. The
optimum conditions obtained were 28min contact time, pH 7, adsorbent dosage 1g/L, and 25°C
temperature for Zinc, 30min contact time, pH 6.5, adsorbent dosage 1g/L, 25°C temperature for
nickel and 30 min contact time, pH 6, and temperature 25°C for copper.
Adsorption data obtained was fitted to various model equations such as Freundlich,
Langmuir, Temkin etc; that suggest best fit to Langmuir isotherm model. The maximum
adsorption capacity of zinc, nickel and copper from Langmuir isotherm were found to be
64.10mg/g, 14.08 mg/g and 11.79 mg/g respectively. The RL values for initial concentration
range 10mg/L-100mg/L were 0.92-0.54, 0.2 – 0.02 and 0.52-0.09 for Zn, Ni and Cu respectively
that were within the favorable range (0<RL<1). The necessary data obtained were interpreted
kinetically by using pseudo first order, and pseudo second order rate kinetics. In all the cases the
kinetics followed pseudo second order rate equation. The contact time variation experiments
were used to study the rate-determining step in the adsorption process. Among the two diffusion
models film diffusion was considered to be the rate controlling step in the adsorption mechanism
because of its lower diffusion coefficients. The negative values of ∆G◦and ∆H◦ indicate that the
process was thermodynamically spontaneous and exothermic in nature.
In Co adsorption studies using batch experiments there was no significant effect on the
adsorption of zinc due to the presence of nickel. In contrast, the removal of nickel decreased
from 57.40% for the single-ion nickel solution to 48% in the presence of zinc co-adsorption.
The ability of SIP waste to adsorb zinc and nickel in a fixed bed column was investigated
using Perspex fixed bed column. The effects of operating parameters such as bed height and flow
rate were studied. The percentage metal adsorption increased from 40% – 62.05% and 31.23%x
56.43% for zinc and nickel respectively with increase in bed height form 5cm to 15cm. Increase
in flow rate from 10mLmin-1 to 20mLmin−1 witnessed decrease in removal from 60.75% to
40.92% for zinc and 56.17% to 31.23% for nickel. At the end, an attempt has also been made to
model the data generated from column studies using the empirical relationship based on Thomas
model. From the results it was observed that Qo values calculated from the Thomas model is
close to the Q, exp values obtained experimentally for both zinc and nickel. The column
regeneration studies were carried out for one adsorption–desorption cycle using the elutant 0.1N
HCl. On the basis of the results, SIP waste can be economically and efficiently used as an
adsorbent for the removal of metal ions from wastewaters.
xi
1 INTRODUCTION
1.1 INTRODUCTION
Environmental pollution is the most gruesome ecological crisis to which the whole world
is engrossed today. It is due to global rise in population and our hunt to lead comfortable life
resulting in urban industrial technology revolution and rapid exploitation of natural resources by
man, in short, population explosion. Now a days Water pollution is becoming great threat to
mankind as most of our daily activities are related to water. Water is an essential natural
resource, which is crucial for a variety of purposes. It is a vital constituent of all animal and
vegetable matters. It is also a necessary ingredient of animal and plant life. Its uses include
drinking and other domestic customs, industrial cooling, power generation, agriculture,
transportation and waste disposal. There are mainly three types of water sources present, namely
surface water, under river flow, ground water. Surface waters and ground waters are greatly
affected by pollution. The industrial effluent containing heavy metals are the main source of
pollution in these water bodies.
Heavy metals are elements having atomic weights between 63.5 and 200.6, and a specific
gravity greater than 5.0 (Srivastava and Majumder, 2008). Rapid industrialization and
urbanization has lead to excessive release of heavy metals into aquatic systems. Industries such
as metal plating facilities, mining operations, fertilizer industries, tanneries, batteries, paper
industries and pesticides galvanizing plants, stabilizers, thermoplastics, pigment manufacture,
etc., discharge heavy metals and wastewaters directly or indirectly into the environment
increasingly, especially in developing countries. Due to their toxicity and non-biodegradability
they accumulate in food chain posing severe damage to living organisms and many heavy metal
ions are known to be toxic or carcinogenic. Toxic heavy metals of particular concern in treatment
of industrial wastewaters include zinc, copper, nickel, mercury, cadmium, lead and chromium.
Thus, treatment of industrial wastewater containing soluble heavy metals has become essential in
order to increase the quality of water.
Zinc is an essential trace element being used in enzymatic reactions in humans (Gul, et
al., 2009). Its extended and excessive ingestion often lead to toxic effects such as carcinogenesis,
1
mutagenesis and teratogenesis as a result of bioaccumulation (ATSDR, 1993). Intake of zinc
ranging from 100 to 150 mg/day interferes with copper metabolism and causes low copper
status, reduced iron function, red blood cell microcytosis, and neutropenia, reduced immune
function, and reduced levels of high-density lipoproteins. There are other reported effects
including lethargy, anemia, vomiting and dizziness (Oyaro et al., 2007). According to the WHO
standards the maximum contamination level of zinc is 5.0 mg/L.
Nickel is one of the heavy metals, an essential constituent for both plants and animals
with very low concentrations. Nickel exceeding its critical level might bring about serious lung
and kidney problems besides gastrointestinal distress, pulmonary fibrosis and skin dermatitis
(Borba et al., 2006). Moreover nickel is human carcinogen. According to the WHO standards the
discharged level of nickel into surface waters is 0.02 mg L−1 [3].
Copper is an important engineering material with wide industrial application and is an
essential factor for animal metabolism. Extensive intake of Cu causes hemolysis, hepatotoxic and
nephro toxic effects vomiting, cramps, convulsions, or even death (Krishnamurthy and
Vishwanathan, 1991; Paulino et al., 2006). The maximum contaminant level for copper in
surface water is 1.3 mg/L (US EPA).
Considering the harmful effects of these heavy metals, it is essential to bring these heavy
metals in the waste water to their permissible limits. Various conventional treatment techniques
are available for the heavy metal removal from water and wastewater which includes
hydrometallurgical techniques, oxidation, reduction, precipitation, electro dialysis, membrane
filtration, flotation, ion exchange, reverse osmosis, and adsorption (Esalah et al., 2000;. Canet et
al., 2002; Zouboulis et.al., 1997). Most of these processes suffer from high operating cost.
Adsorption is one of the most versatile techniques for the removal of heavy metals from low
concentration wastewater containing heavy metal. The adsorption process has many advantages
such as low cost mainly due to utilization of industrial, biological and domestic wastes as
adsorbent, low operational cost, ease of operation compared to other processes, re-usability of
adsorbent after regeneration. On the other hand the high cost of activated carbon (AC) limits its
use in adsorption. To evade the high cost of activated carbon so many varieties of low-cost
adsorbents have been developed and tested to remove heavy metal ions. Different adsorbents
typically used include modified flax shive (El-Shafey et al., 2002), rice husk ash (Srivastava et
2
al., 2006), waste biomass, waste activated sludge (Norton et al., 2004), wood sawdust Modified
Sugarcane Bagasse (Pereira, et al., 2009) and Lignite (Pentari, et al., 2009). In spite of several
investigations using different adsorbents still new adsorbents are sorted due to increasing
demand for treatment of industrial effluents.
Some of the industrial solid waste materials are being used as adsorbents these days. One
of such kind is the waste produced by sponge iron plant was used in the present study. Sponge
iron plant waste is major source of dust pollution and it needs to be treated well before disposal.
It has been found out that around 1.6-1.75 tonne of Fe, 1.2- 1.5 tonne of coal & 0.035 tonne of
dolomite are required for production of one tonne of sponge iron. This results in production of
0.54 tonne of solid waste which includes 0.25 tonne of dust and 0.29 tonne of coal char. Due to
non- availability of good grade of coal, the amount of char fines increases. The size of char
varies in size of 0.5 mm to 3 mm thus becomes difficult to handle. Apart from this, it takes a lot
of area for disposal. A 100 TPD plants requires 10 acres of land annually for disposal of solid
waste (Patra et al., 2009).
In the present study the adsorption of zinc, nickel and copper ions from aqueous
solution using surface modified sponge iron plant waste (char) as an adsorbent was investigated.
Batch studies were conducted using synthetic zinc, nickel, and copper solution. The influence of
pH, contact time, initial metal ion concentration, temperature and adsorbent concentration were
investigated to optimize the conditions for maximum zinc, nickel, and copper removal. The
experimental data obtained were calculated and fitted using adsorption isotherms, various kinetic
models, and thermodynamic studies were conducted. Fixed bed column studies were conducted
to determine their practical applicability. The effect of parameters such as flow rate and bed
depth on the shape of the breakthrough curve was examined. Thomas model was used to evaluate
and predict the adsorption performance and capacity of SIP waste for zinc and nickel adsorption
in a fixed-bed column. Desorption and column regeneration of zinc and nickel adsorption was
also investigated.
1.1.1 OBJECTIVE
The overall objective of the study is to reduce Zn, Cu & Ni concentrations in aqueous solution
using an industrial waste (Sponge iron plant waste). The specific objectives are as follows:
 To characterize sponge iron plant waste.
3
 To optimize the process parameters involved in adsorption of heavy metals from
waste water using the waste
 To evaluate the adsorption capacity and rate of mass transfer through batch and
column studies respectively.
 To evaluate the regeneration capacity of the adsorbent.
4
2 LITERATURE REVIEW
Heavy metals are one of the most hazardous pollutants to the environment because of their
higher toxicity and non-biodegradability even at trace concentrations. They are cumulative
poisons which are capable of being assimilated and accumulate in food chain posing a severe
damage to the plant and living organisms (Idris, et al. 2004). Heavy metals can enter water
bodies by industrial and consumer waste, or even from acidic rain breaking down soils and
releasing heavy metals into streams, lakes, rivers, and groundwater. Heavy metals such as lead,
zinc, nickel, mercury, cadmium, copper, arsenic, cobalt, chromium, bismuth, ferrous etc. have
been identified as poisonous to ecosystem and human health even present in traces.
2.1 ZINC
2.1.1 IMPORTANCE OF ZINC
Zinc metal and zinc alloys are very resistant to corrosion. Due to its extensive usage in
electroplating, metal plating, chemical manufacturing industries, etc. the demand of zinc has
been increasing globally. Important uses of zinc are in metal plating and galvanizing (for
example in producing car bodies) and as an alloy in plumbing and central heating systems.
Zinc compounds also have an enormous range of useful properties and are used in a very wide
range of products. Some important applications are specified below:
 In paint industry, zinc oxide used as a white pigment, zinc chromate used as a rust
inhibitor.
 Zinc chloride used as an electrolyte in dry-cell batteries.
 Depleted Zinc-64 is used widely in the nuclear industry.
 Used as protective coatings for steel.
 Casting industries.
 Used as an alloying metal with copper to make brass.
 Used as chemical compounds in rubber and paints.
 Used as sheet zinc and for galvanizing iron.
5
 Zinc oxide used in ointments for burns and skin protection, zinc pyrithione used in antidandruff shampoos.
 Used in Lozenges.
 Zinc chloride used in the manufacture of artificial silk and in printing and dyeing textiles.
Apart from industrial uses zinc plays a vital role in human metabolism. It is essential for
plants, animals, and microorganisms (Sugarman 1983; Prasad. 2008) and used by more than one
hundred specific enzymes for their catalytic function (Cousins 1996). It helps in increase of
immune system (Solomons 1998; Prasad A.S 1995), wound healing (Heyneman 1996), protein
synthesis (Prasad A.S 1995), normal taste and smell (Prasad A.S 1997), and is needed for DNA
synthesis (National Academy Press, 2001; Prasad 1995), and cell division (Prasad 1995). Zinc is
stored in the brain, in specific synaptic vesicles by glutamatergic neurons (Bitanihirwe and
Cunningham 2009) and can "modulate brain excitability"(Hambidge et al., 2007). It plays a key
role in synaptic plasticity and so in learning (Nakashima and Dyck 2009).
2.1.2 HARMFUL EFFECTS OF ZINC
Zinc is an essential trace element used for enzymatic reactions in humans (Gul 2009) and
its extended and excessive ingestion may lead to several toxic such as carcinogenesis,
mutagenesis and teratogenesis as a result of its bioaccumulation (CONAMA, 2005). Its toxicity
can occur in both severe and chronic forms. Intake of zinc ranging from 100 to 150 mg/day
interferes with copper metabolism and causes low copper status, reduced iron function, red blood
cell microcytosis, and neutropenia, reduced immune function, and reduced levels of high-density
lipoproteins (Hooper et al., 1980). Ingesting 200–800 mg/day of zinc can cause abdominal
cramp, nausea, vomiting, and loss of appetite, diarrhea, headaches etc (National Academy Press,
2001). There are other reported effects including lethargy, anaemia, and dizziness.
The AREDS have done a study by taking 80 mg per day of zinc in the form of zinc oxide
for 6.3 years, on average have revealed that there was a significant increase in hospitalizations
for genitourinary causes, raising the possibility that constantly high intakes of zinc harmfully
affect some aspects of urinary physiology (Lomaestro and Bailie 1995). Zinc allied with other
metals, such as lead, copper, and cadmium causes additional air pollution. The most general
6
effect caused by zinc air pollution is “metal – fume fever “which is as a consequence of the
inhalation of zinc oxide fumes (NAPCA 1969).
2.1.3 SOURCES OF ZINC POLLUTION
The two major sources of zinc in to the aquatic systems are domestic and industrial discharges.
The details of the discharges are given below.
2.1.3.1 I NDUSTRIAL SOURCES
Most of the zinc pollution is caused by industries. Zinc is released from industries such as:
coal-burning power plants, iron and steel industries, manufacturing processes involving
metals; and atmospheric fallout (Denton, et al. 2001). Other sources are

Electroplating industries.

Pulp and paper industries.

Rubbers manufacture industries.

Pharmaceutical industries.

Textile mills.

Mining industries,

Pharmaceutical industries

Automobile emission, etc.
2.1.3.2 D OMESTIC SOURCES

Zinc occurs naturally in many foods

Some toiletries contain zinc - for example medicated shampoos with zinc pyrithione to
control dandruff.

Residues of zinc from zinc-plated cold water tanks leach into tap water and are flushed
away when water is used.
2.1.4 DIFFERENT TECHNIQUES FOR ZINC TREATMENT
According to the WHO standards the maximum contamination level of zinc is 5.0 mg/L. The
majority of the industries are discharging effluents containing zinc more than its permissible
limit. Thus the removal of zinc from the industrial wastewater before releasing it has turn out to
7
be necessary. There are several convectional techniques available for the removal of zinc ions
from wastewaters.
 Chemical precipitation.
 Ion -exchange.
 Membrane filtration.

Electrochemical methods.
 Biological methods.
 Adsorption methods.
2.1.4.1 C HEMICAL PRECIPITATION
Chemical precipitation is an effective and widely used technique in industries (Ku and Jung,
2001) because of its ease of operation and being inexpensive.
Charerntanyarak (1999) worked with chemical coagulation and precipitation by lime to
treat synthetic wastewater consisting of Zn at 450 mg/L. He examined that the optimum pH was
more than then 9.5. Ghosh et al. (2010) employed electro- Fenton process and chemical
precipitation to treat rayon industry waste water containing Zn2+ (32 mg/L). Results shown about
99-99.3% removal was achieved in the pH range 9-10 using lime precipitation. Chen et al.,
(2009) also used lime precipitation for removal of zinc containing 100mg/L. He found that about
99.37-99.6% removal was obtained with pH range 7-11. Alvarez et al., (2007) employed
precipitation process to treat zinc at a 1.35mM. They found that 94% removal was achieved at
pH 3 using H2S as precipitant.
2.1.4.2 I ON – EXCHANGE
Ion-exchange processes have been extensively used for removal of heavy metals from
wastewater due to their advantages, such as high treatment capacity, high removal efficiency and
fast kinetics (Kang et al., 2004). Among the materials used in ion-exchange processes, synthetic
resins are commonly preferred as they are effective to nearly remove the heavy metals from the
solution (Alyüz and Veli, 2009).
(Alyüz and Veli, 2009) employed ion- exchange process using Dowex HCR S/S cation
exchange resin was evaluated for removal of zinc from aqueous solutions. They found that the
8
process was pH-dependent and 98% removal efficiency was obtained at pH 6. They also
investigated equilibrium distribution coefficient (D) 2.25×104 whereas separation factor α is
0.1029. Doula (2009) worked on clinoptilolite -Fe system for removal of Zn from drinking water.
He observed that the system has a very good metal adsorption capacity and for many of the cases
the treated water samples were suitable for human consumption or for agricultural use. Heikki
(1999) tested the removal efficiency of zinc from metal plating industy on four chelating
exchangers; which were Amberlite IRC 718, Duolite ES 467, Spheron Oxin, and oxine
impregnated active carbon and on an inorganic sodium titanate exchanger. He found that all the
five exchangers performed well with 99% removal efficiency.
2.1.4.3 M EMBRANE FILTRATION
Membrane filtration technologies were generally used in removal of heavy metals as they
are highly efficient, can be easily operated and space saving. The membrane processes
commonly used for metal removal from the wastewater are ultrafiltration, reverse osmosis, and
electrodialysis.
Landaburu-et al., (2009) studied the removal of zinc from synthetic wastewater by MEUF
(micellar enhanced ultrafiltration) using SDS. They observed that the removal is surfactant to
metal molar ratio (S/M) dependent, and rejection coefficients up to 99% were achieved when the
S/M was above 5. Huang et al., (2010) employed with Polysulfone membrane using SDS
surfactant. They found that about 92-98% removal of zinc with 50mg/L initial zinc
concentration. Ipek (2005) employed reverse osmosis process to remove zinc from aqueous
solution. He found 98.9% removal at an operating pressure 1100kpa. Abbas et al., (2008) worked
with electrolytic method for the removal of zinc from waste water using a flow-through cell with
amalgamated copper screen cathode. They investigated that a flow-through porous electrode
made of amalgamated copper screen can be an effective device in removal of Zinc from
simulated effluents, and the concentration of Zn (II) was reduced to 5mgL-1 during recirculation
times ranging from 100 to 190min, depending on the flow rate.
2.1.4.4 E LECTROCHEMICAL METHODS
Electrochemical methods involve the plating-out of metal ions on a cathode surface and
can recover metals in the elemental metal state. Electrochemical wastewater technologies are
9
rarely used as they involve relatively large capital investment and the expensive electricity
supply. However, with the stringent environmental regulations regarding the wastewater
discharge, electrochemical technologies have regained their importance worldwide during the
past two decades (Wang et al., 2007b).
Kabdaslı et al., (2009) employed electro-coagulation using stainless steel electrodes for
reduction of zinc from waste water originating from metal plating industry. Their study
demonstrated that 100% removal was achieved with an applied current density 9 mA/cm2 at pH
6. Casqueira et al., (2006) reported 96% removal of zinc at optimum pH 7, current density
8mA/cm2 by using electro-coagulation. Nafaˆa et al., (2004) investigated the performance of
electro-coagulation, with aluminium sacrificial anode, in the treatment of Zn2+containing
wastewater. Belkacem et al., (2008) employed electro-filtration technique with aluminium
electrodes to remove zinc from wastewater. They found 99% removal at optimum parameters.
2.1.4.5 B IOLOGICAL METHODS
The use of biological process for wastewater treatment containing heavy metal ions is a
recent development although the technique has been widely used in chemical and pharmaceutical
industries in a commercial scale. It is a very promising process in the removal of heavy metal
contaminants. The major advantages of biosorption are its high effectiveness in reducing the
heavy metal ions and the use of inexpensive biosorbents. Biosorption processes are particularly
suitable to treat dilute heavy metal wastewater. In this process algal, bacteria, fungi, yeast etc are
used as biosorbents.
Aminah and Babu, (2009) employed biosorption process using water hyacinth as biosorbent, to
remove Zinc (II) from aqueous solution. They found the maximum removal at pH 5.4, adsorbent
dosage 0.2g, initial metal concentration of 10 mg/L and the optimum time contact was at 90
minutes for initial concentration 5 mg/L and 210 minutes for initial concentration 10 mg/L.
Artola and Rigola (1999) reported biosorption of zinc by sludge micro-organisms obtained from
different steps of a conventional SWT plant. They found that the best types of activated sludge
for the process to be thickened, anaerobic and dewatered sludge which removed up to 90–98% of
metal when working at initial zinc concentration lower than 50 mg/l. The biosorption of Zn 2+ by
dried marine green macroalga (C. linum) was studied by Ajjabi and Chouba (2009). They found
that the dried alga produced maximum 1.97 mmol/g uptake at the optimum particle size (10010
315 mm), biosorbent dosage (20 g/L) and initial solution pH 5. Lisa Norton et al 2004 employed
biosorption process for the removal of zinc from aqueous solutions using biosolids. They found
that the process was pH dependent with pH 4 being optimal.
Although all these wastewater treatment techniques can be employed to remove heavy
metals, they have their intrinsic advantages and boundaries. As chemical precipitation is a simple
and economical process, the heavy metals removal from aqueous solutions has been traditionally
carried out by this process. But, chemical precipitation can be used only to treat high
concentration wastewater containing heavy metal ions and it is ineffective when metal ion
concentration is low. And chemical precipitation produces large amount of sludge to be treated
with great difficulties.
Ion exchange has been widely applied for the removal of heavy metal from wastewater.
On the other hand, ion-exchange resins must be regenerated by chemical reagents when they are
exhausted and the regeneration can cause serious secondary pollution. And it is expensive,
particularly when treating a large amount of wastewater containing heavy metal in low
concentration, so they cannot be used at large scale.
Membrane filtration technology can remove heavy metal ions with high efficiency, but it
is having demerits such as high cost, process complexity, membrane fouling and low permeate
flux which limited their use in heavy metal removal.
Electrochemical techniques for heavy metal removal are considered as the most rapid and
well-controlled that require fewer chemicals, provide good reduction yields and produce less
sludge. But, electrochemical technologies involving high initial capital investment and the
expensive electricity supply, this restricts its development.
The demerits of all the above process made to search for other process which can
overcome all the difficulties in the above process. One of such kind is adsorption process.
2.1.4.6 A DSORPTION METHODS
Adsorption is as an effective and economic method for heavy metal wastewater treatment
among all the techniques. The adsorption process offers flexibility in design and operation and in
many cases will produce high-quality treated effluent. In addition, because adsorption is
sometimes reversible, adsorbents can be regenerated by suitable desorption process. In
adsorption process a single or a group of ions/compounds get accrued on the surface of another
11
solid or liquid. The substance on which the adsorption takes place is known as adsorbent and the
substance, which gets adsorbed, is called adsorbate. Adsorption is classified into two types based
on the extent of attraction between the adsorbent and adsorbate.
 Physical adsorption or vanderWaal‟s adsorption.
 Chemisorption.
In physical adsorption, the forces of attraction between the molecules of the adsorbate and the
adsorbent are of the weak van der Waals' type. Because the forces of attraction are weak, the
process of physisorption can be easily reversed by heating or decreasing the pressure of the
adsorbate in gas adsorption and established rapidly. The heat of adsorption are low i.e. about 20
– 40 kJ mol-1. In physical adsorption compound formation dose not takes place. Physical
adsorption can be of two types, i.e., monolayer adsorption and multi-layer adsorption. In
chemisorptions, the forces of attraction between the adsorbate and the adsorbent are similar to
those of chemical bonds which are very strong. In this process, the heat of adsorption usually
varies from 40 to 400kJ/mol. In this case surface compounds are formed. This process is related
with significantly high activation energy and therefore termed as activated adsorption. It is
moderately a slow process. Chemisorptions, in general, is an irreversible process because of
strong electrostatic force of interaction between the adsorbent and adsorbate molecules.
Physical adsorption is very effective, particularly at a temperature close to the critical
temperature of a given fluid. Chemisorption occurs usually at temperatures much higher than the
critical temperature and by contrast to physical adsorption, is a specific process, which can only
take place on some solid surface for a given fluid. Contrary to physical adsorption,
chemisorption leads to monolayer adsorption. Under favourable conditions, both the processes
can occur concurrently or alternately. Physical adsorption is accompanied by a decrease in free
energy and entropy of the adsorption system and, thereby, this process is exothermic in nature.
The majority of the adsorbents used in the industrial process have complex porous
structures that consist of different sizes and shapes of pores. The total porosity is typically
classified into three groups: micro pores (diameter, d<2 nm), meso pores (2<d<50 nm) and
macro pores (d>50 nm). In adsorption process the pore size is important. Because the size of
micro pores are comparable to those of adsorbate molecules, all atoms or molecules of the
adsorbent can interact with the adsorbate species. This is the basic difference between adsorption
12
in micro, meso and macro pores. As a result, the adsorption in micro pore is essentially a pore
filling process in which the main controlling factor is the pore volume. Mesopores walls are
formed by a large number of adsorbent atoms or molecules, and the boundary of the inter-phase
has a discrete physical meaning. That means the adsorbent surface area has a physical meaning.
In macro pores the adsorption forces do not occur all through the void volume, but they take
place at a close distance from their walls. Therefore, the mono and multilayer adsorption take
place successively on the surface of meso-pores and their final fill proceeds according to the
mechanism of capillary adsorbent condensation. The basic parameters illustrate mesopores are:
specific surface area, pore volume and pore size or pore-volume distribution. The mechanism of
adsorption on the surface of macro pores is similar from flat surfaces. Adsorption on this surface
is usually neglected as the specific surface area of macro-porous solid is very small. The
capillary adsorbate condensation does not occur in macro pores (Saroj, 2007).
Adsorption is a technology that appears more technically and economically feasible. The
advantages of adsorption over other technologies are that no additional sludge is produced,
additional reagents to overcome high alkalinity are not needed, and the pH of discharged
wastewater is unaffected Urano and Tachikawa (1991).The adsorption process has many
advantages such as:

Low cost of adsorbent.

Easy availability of adsorbent.

Utilization of industrial, biological and domestic wastes as adsorbent.

Low operational cost.

Ease of operation compared to other processes.

Re-use of adsorbent after regeneration.

Capacity of removing heavy metal ions over a wide range of pH and to a much
lower level.

Ability to remove complex form of metals that is generally not possible by other
conventional method.

Environment friendly, cost effective and technically feasible alternative due to
utilization of biomaterials (Saroj, 2007).
13
Adsorption studies were carried out using a varity of adsorbents such as: Activated carbon, low
cost adsorbents for biomass, waste sludge, rice husk, sugarcane bagasse, lignite etc.
Activated carbon (AC) adsorbents are widely used in the removal of heavy metal
contaminants. It contains a large micropore and mesopore volumes which results in high surface
area. Because of this it is widely used in commercial scale. A large number of researchers are
studying the use of AC for removing heavy metals (Jusoh et al., 2007; Kang et al., 2008). Leyva
Ramos et al, (2002) investigated adsorption of zinc from aqueous solution onto commercial
activated carbons C, F-400, F-300 and Centaur HSL in a batch adsorber. They found that
adsorption isotherm for Zn (II) was dependent on solution pH and maximum adsorption uptake
was achieved at pH 7.
Due to the high cost of Activated carbon limits its use in adsorption. Many varieties of
low-cost adsorbents have been developed and tested to remove heavy metal. Hasan Cesur and
Nilg¨un Balkaya 2007 examined the removal of zinc (II) ions from aqueous medium by
phosphogypsum. They found the maximum adsorption of the zinc (II) ions on the
phosphogypsum was obtained at the pH values between 9.0 and 10.0 and observed that the
adsorption equilibrium was reached in 40 min and the adsorption data fitted well to Freundlich
model. The adsorption capacity of phosphogypsum for zinc (II) ions was determined to be 2.57
mg g−1. Sachin and Gaikwad (2011) studied the removal of zinc from electroplating industrial
wastewater using a cheap adsorbent, cork powder. They found 98% removal of zinc in synthetic
wastewater whereas the removal percentage for the electroplating industrial wastewater was
91%. The optimum pH was 6. Bayat, (2002) investigated the removal of zinc from aqueous
solution two different Turkish fly ashes (Afsin-Elbistan and Seyitomer). Results revealed that at
pH 8 the maximum uptake was obtained. Among the two adsorbents he found that the fly ash
with high calcium content (Afsin-Elbistan) as an effective activated carbon.
Apart from these adsorbents many low cost adsorbents from agriculture waste are also in
use. El-Shafey (2010) used a carbonaceous sorbent prepared from rice husk via sulfuric acid
treatment to remove zinc from waste water. He found Sorption of Zn (II) was extremely low at
low pH values and increased with pH rising with a decrease in the final pH due to protons release
in solution and Ea was found to be ∼13.0 kJ/mol for Zn (II) sorption indicating a diffusioncontrolled ion exchange mechanism. Olayinka et al., (2007) reported the use of waste tea,
14
coconut shell and coconut husk as potential low cost adsorbents for removal of Zn (II) from
electroplating plant effulent. They observed that all the three adsorbents showed high rate of
adsorption (cocunut shell, 99.74%, cocunut husk 99.76% and waste tea 90.74% removal).
Jang-Soon et al., (2010) studied removal of zinc from aqueous solutions by scoria (a
vesicular pyroclastic rock with basaltic composition) from Jeju Island, Korea. They found up to
63% zinc removal after a reaction time of 24 h under a sorbate concentration of 1mM and the
solution pH of 5.0. Pereira 2010 used new chelating material derived from wood sawdust,
Manilkara sp., and chemically modified sugarcane bagasse synthesized to remove Zn2+ from
aqueous solutions and electroplating wastewater. Zn2+ adsorption capacities were found to be 80
mg/g for ES and 105 mg/g for EB whereas for the industrial wastewater these values were found
to be 47 mg/g for ES and 45 mg/g for EB. Shukla and Pai (2005b) batch adsorption studies to
remove Zn(II) from waste water using Reactive Orange 13 modified Groundnut shells. The
maximum uptake found was 9.57mgg-1. sc´iban et al.,. (2006a) employed adsorption of zinc on
to sodium hydroxide modified Sawdust (Poplar tree). The adsorption capacity was to be
15.8mgg-1. Medhat (2007) reported the use of dried non-living biomass (NB) of different
Pseudomonas strain as adsorbents to remove Zn (II) from waste water. He found optimum pH as
4.4 at which maximum metal removal was achieved.
2.2 NICKEL
2.2.1 IMPORTANCE OF NICKEL
Nickel is a metal of widespread distribution in the environment. There are almost 100 minerals
of which Nickel is an essential constituent and which have many industrial and commercial uses.
Not only for industrial use, but it is also an essential element for healthy animals, microorganisms, plants and probably for humans. It is a versatile element and forms alloy with most
metals.
Nickel and nickel alloys are used for a wide variety of applications, the majority of which
involve corrosion resistance and/or heat resistance. Some important applications are specified
below:

Aircraft gas turbines.

Steam turbine power plants.
15

Medical applications.

Nuclear power systems.

Chemical and petrochemical industries.

Making of austenitic stainless steel.

Used as a catalyst in certain chemical reactions.

Used in structural work and in electroplating.

Used as an alloying element in ferrous alloys, low cost steels, cast iron etc.

Rechargeable batteries, coinage, foundry products, and plating.

In armour plates and burglar-proof vaults.
A number of other applications for nickel alloys involve are:

Alloy alnico is used in magnets.

In crucibles for chemical laboratories.

Smart wire, or shape memory alloys are used in robotics.

Monel metal, a copper-nickel alloy being highly resistant to corrosion is used for ship
propellers, kitchen supplies, and chemical industry plumbing etc.
Apart from industrial applications nickel plays a crucial role in plant and micro organism
metabolism (Astrid Sigel, 2008). Nickel is essential for plant growth (Brown, 1987). It is also an
essential component of hydrogenases involved in nitrogen fixation and other associative bacterial
processes, and it clearly influences plant response to disease.
2.2.2 HARMFUL EFFECTS OF NICKEL
Nickel is one of the heavy metal, which is an essential constituent for both plants and animals,
but is required in very low concentrations. Extensive intake of nickel in large quantities has the
following consequences:

Higher chances of development of lung cancer, nose cancer, larynx cancer and
prostate

Cancer.

Sickness and dizziness after exposure to nickel gas.

Lung embolism.

Respiratory failure.
16

Birth defects.

Asthma and chronic bronchitis.

Allergic reactions such as skin rashes, mainly from jewellery.

Heart disorders.

Paranasal sinuses.

Extra weakness etc (Al-Asheh and Duvnjak, 1997, Kadirvelu 1998, Beliles 1979).
Nickel fumes are respiratory irritants and may cause pneumonitis. Exposure to nickel and
its compounds may result in the development of a dermatitis known as “nickel itch” in sensitized
individuals.
2.2.3 SOURCES OF NICKEL POLLUTION
Majority of the nickel is discharged from industries and mining.

Nickel miners, smelters and refiners.

Nickel alloy manufacturers.

Iron and steel industries.

Electroplating industries.

Batteries and metal plating.

Insecticides and fungicides.

Photography

Electrical wiring.

Smelting industries.

Fertilizer industries.

Nickel containing alloys such as in coinage in various forms of 'costume' or 'fashion'
jewellery etc.
2.2.4 DIFFERENT TECHNIQUES FOR NICKEL REMOVAL
According to the WHO standards the maximum contamination level of nickel is 0.02 mg L−1.
The majority of the industries are discharging effluents containing zinc more than its permissible
limit. Thus the removal of zinc from the industrial wastewater before releasing it has turn out to
17
be necessary. There are several convectional techniques available for the removal of zinc ions
from wastewaters.

Chemical precipitation.

Ion -exchange.

Membrane filtration.

Electrochemical methods.

Biological methods.

Adsorption methods.
2.2.4.1 C HEMICAL PRECIPITATION
Naim, et al (20100 employed chemical precipitation to remove nickel from electroplating
industry wastewater using three precipitating agent namely hydroxide, sulfide and carbonate.
They found that sulfide precipitation was a viable option for the treatment of electroplating
industry wastewater as compared to hydroxide and carbonate precipitation. Stephen et al, (2006)
investigated removal of nickel from synthetic nickel plating wastewater using Sulfide and
Carbonate for Precipitation and Co-precipitation. It was found that the optimum removal was
achieved at pH 11 where a residual total nickel concentration of 0.1 mg/L was obtained with a
sulfide: nickel weight ratio of 2.0 and a carbonate: nickel weight ratio of 20.0. Animes et al,
(2008) reported the removal of nickel from plating rinse effluent using chemical techniques.
They observed that Nickel concentration can be reduced below the discharge limit from the
industrial plating effluent by chemical precipitation and coagulation at pH above 8.
Papadopoulos et al, (2003) employed chemical precipitation to remove Ni (II) from waste water.
They observed 85% removal at pH 10.5 with in 1 hr contact time.
2.2.4.2 I ON - EXCHANGE
Argun, (2008) investigated the use of clinoptilolite ion-exchange resin in removal of
nickel from wastewater. He conducted batch experiments at different varying the parameters and
achieve 93.6 % removal at 7 pH, and adsorbent dose 15 g/L. Kumar et al., (2010) employed ion
exchange process to remove nickel from aqueous solution using Ceralite IR 120 cationic
exchange resin (CXR) as an adsorbent. They observed maximum Ni2+ removal at pH 5.0 and the
18
equilibrium was attained at 35 min.. Elshazly ,and. Konsowa (2003) reported the removal of
nickel ions from wastewater polluted with nickel chloride using a cation-exchange resin in a
stirred tank reactor. They found that mass transfer coefficient decreases with increasing nickel
ion concentration and increases with increasing the degree of stirring and temperature and nickel
ion removal rates up to 88.5% were obtained. Rodrıguez-Iznaga et al., (2002) used natural
clinoptilolite from Caimanes deposit (Moa-Cuba) for the nickel removal from aqueous solution
by ion exchange process. They tested stability of clinoptilolite as an exchanger for Ni 2+ under
hydrothermal conditions and high ammonia concentrations. No loss in the clinoptilolite exchange
capacity of Ni2+ ions during the Ni2+ removal–elution cycles was observed.
2.2.4.3 M EMBRANE FILTRATION
Danisa and Aydiner (2009), employed ultra filtration process to remove nickel from
wastewater by micellar enhanced ultrafiltration using Sodium lauryl ether sulfate surfactant. 98%
removal was obtained at an optimum pH 7. Barakat and Schmidt, (2010) reported the use of
polymer enhanced ultrafiltration (PEUF) to remove nickel from aqueous solution using Carboxy
methyl cellulose complexing agent. Maximum removal (99.1%) was achieved at pH 7 and 10
mg/L initial metal concentration. Molinari et al., (2008) used PEI as a polymer to study the
complexation-ultrafiltration process in the removal Ni (II) aqueous solution. From the
Preliminary tests he found the optimal chemical conditions for Ni (II) complexation by the PEI
as pH > 8.0, and polymer/metal weight ratio of 6.0.
(Mohsen-Nia et al., 2007) reported that Ni2+ ions were successfully removed by the RO
process and the rejection efficiency of the ions increased up to 99.5% by using Na2 EDTA at 5
atm operation pressures. Ipek, 2005, employed reverse osmosis process to remove nickel from
aqueous solution. He found 99.3% removal at an operating pressure 1100kpa with initial metal
concentration 44-169 mg/L. Galaya, and Poonpetch (2002) investigated membrane separation
process using two membrane types, cellulose acetate microfiltration membrane with pore size 0.2
μm and polysulfone ultrafiltration membrane with MWCO of 30 kDa to remove nickel ions from
electroplating wastewater. Experimental results showed the maximum rejection % (96.00-97.39)
at pressure 50 kPa.
2.2.4.4 E LECTROCHEMICAL METHODS
19
Heidmann and Calmano (2010) tested the performance of an electro-coagulation system
for Ni removal from a galvanic wastewater in laboratory scale. Results revealed that the best
cleaning and the most effective removal could be achieved with a combination of Fe- and Alelectrodes and initial pH > 5.0. Kabdaslı et al., 2009 employed electro-coagulation using
stainless steel electrodes for reduction of nickel from waste water originating from metal plating
industry. Their study demonstrated that 100% removal was achieved with an applied current
density 9 mA/cm2 at pH 6. Heidmann and Calmano (2008) investigated the performance of an
electro-coagulation process with aluminium electrodes for removing Ni2+. They observed that the
removal rates were not influence by the initial concentrations ranging from 50 mg/L to 5000
mg/L. Khelifa et al., (2005) employed electro-flotation process to remove nickel from
wastewater. They found 98% removal at pH 6 with an applied current 0.3A
2.2.4.5 B IOLOGICAL METHODS
Parameswari et al, (2009) investigated the removal of nickel using Azotobacter
chroococcum, Bacillus sp. and Pseudomonas fluorescens isolated from sewage effluent and
sewage irrigated soils. The maximum nickel removal (84.32 % and 90.98 % by A. chroococcum,
Bacillus sp. and P. fluorescens respectively) achieved was found to be 72 hr with an initial
concentration of 25ppm. Shankar et al., (2007) employed biosorption process to remove nickel
from industrial wastewater using heavy metal resistant fungi and bacteria isolated from the soil
samples of an electroplating industry. They observed that optimal pH for fungal isolates was
lower (5–5.2) than that for bacterial isolates. Wong and. Fung (1997) reported the removal of
nickel from aqueous solution using Cells of Enterobacter sp. 4-2 immobilized on magnetites.
They observed that the optimal conditions for immobilized cells to remove Ni2+ from aqueous
solution were buffer at an alkaline pH, the temperature higher than 37°C, and the retention time
longer than 30 min. Manuela et al., (2010) investigated removal of nickel from electroplating
industry waste water using Brewer‟s Yeast Strain of Saccharomyces cerevisiae. The maximum
removal was attained at pH 6.
2.2.4.6 A DSORPTION
20
Yu Ji (2010) used activated carbon to remove nickel from aqueous solution. He found
that nickel adsorption increased as the pH increases and started decreasing after pH 6.
Hasar,(2003) employed adsorption process to remove nickel from aqueous solution using
Activated carbon prepared from almond husk by activating without (MAC-I) and with (MAC-II)
H2SO4 at different temperatures. He found the maximum removal of Ni (II) to be 97.8% at initial
concentration of 25mg/l, the adsorbent concentration of 5g/l and optimum pH 5. Kannan and
Thambidurai (2008) investigated removal of nickel from aqueous solution by adsorption on to
Palmyra palm fruit seed carbon (PPFSC) and commercial activated carbon (CAC). They found
that adsorption of nickel (II) was highly pH dependent and the results showed that pH range from
4.0 to 6.0. Demirbas (2002) reported removal of Ni (II) from aqueous solution using activated
carbon prepared from hazelnut shell as an adsorbent.
Apart from commercial activated carbons many low cost adsorbents are in use to reduce
the operating cost of the process. Chih-Huang, (2002) employed adsorption process to remove Ni
(II) onto sludge–ash, a waste produced from a fluidized bed incinerator combusted primarily
with biosolids. He found from the results of equilibrium studies that the solution pH was the key
factor affecting the adsorption and the adsorption sharply reached a 99% removal at a pH of 8.0
then remained constant over a wide pH region. Periasamy and Namasivayam (1995) used
Activated carbon prepared from peanut hulls (PHC), an agricultural waste by-product, for the
adsorption of Ni (II) from aqueous solution. They observed the quantitative removal of Ni (II)
from 100 mL aqueous solution containing 20 mg/L Ni (II) by 85 mg PHC over a pH range of 4.0
to 10.0. Kumar and. Kirthika (2009) investigated the ability of bael tree (BT) leaf powder to
adsorb nickel, Ni2+, from aqueous solutions through batch experiments. From the experiments
they found the highest removal rate was 60.21% for Ni2+ under optimal conditions and the
monolayer adsorption capacity is 1.527 mg Ni per g BT leaf powder.
Garg et al., (2008) employed adsorption process to remove nickel from aqueous solution
using an agricultural waste biomass, Sugarcane Bagasse as an adsorbent. They found that the
optimum conditions for maximum removal of nickel from an aqueous solution of 50 mg/L were
adsorbent dose (1500 mg/L), pH (7.52) and stirring speed (150 rpm). Potgieter 2006 investigated
adsorption of nickel from aqueous solution using palygorskite clay as an adsorbent. The
adsorption capacity (Q0) calculated from the Langmuir isotherm was found to be 33.4 mg Ni (II)
21
g-1. Monier et al., (2010) reported the use of Cross-linked magnetic chitosan-isatin Schiff‟s base
resin (CSIS) to remove nickel from aqueous solution. From the results they observed that the
best interpretation for the equilibrium data was given by Langmuir isotherm and the maximum
adsorption capacities was 40.15 mg/g.
Onundi et al., (2010) investigated adsorption of nickel from synthesized industrial
wastewater using Granular activated carbon produced from palm kernel shell as an adsorbent.
The maximum sorption capacity (0.130 mg/g) and removal (55%) were obtained at pH 5, and the
equilibrium time was 75 min. Vijayakumaran et al., (2009) testes the efficiency of a
carbonaceous adsorbent prepared from an indigenous waste, by acid treatment in the adsorption
of nickel from aqueous solution. They observed that the process is pH dependent and the
maximum uptake (43mg/g) was obtained at pH 7. The experimental data followed first order
reaction equation and showed that the rate is mainly controlled by intraparticle diffusion.
Pradhan et al., (2005) employed adsorption of nickel from wastewater onto partially converted
crab shell waste, which contains chitosan. They observed the metal uptake by partially converted
crab shell waste was successful and rapid within 5 min.
Shyam et al., (2005) reported adsorption of nickel from aqueous solution on to saw dust.
They observed that the adsorption of the nickel is dependent on the initial concentrations of
adsorbent, sorbate, time of contact and pH. Maximum percent removal of nickel (II) was
obtained at pH 9.0 and contact time 1hr. Atul et al., ( 2011) investigated the use of hydrolyzed
poly-methyl methacrylate (HPMMA) as adsorbent in removal of nickel from aqueous solution.
They found the optimum conditions for the adsorption to be pH 6; temperature 303 K and
adsorbent dose of 5 gL−1 was able to remove 59 % of Ni (II) within 60 min of contact time.
Vieira et al., (2010) studied adsorption of nickel on calcined Bofe bentonite clay from aqueous
solution. They found the maximum adsorption capacity of 1.91mg metal/g of clay at 20◦C and
pH 5.3.
2.3 COPPER
2.3.1 IMPORTANCE OF COPPER
Copper is a metal of choice for technologists and is an important engineering material having a
wide range of industrial applications.
22

An important use of copper is in alloys such as brass, bronze, gunmetal, Monel metal and
German silver.

In ceramics and pesticides.

Used in manufacture of wires for various industries, namely electrical, electronics,
automotive, electrical appliances, white goods, etc.

In copper forming industries (shrivastav, 2009).

Copper tubing is used in plumbing.

Computer heat sinks are made out of copper as copper is able to absorb a high amount of
heat.

Copper compounds are widely used as insecticides and fungicides.

Used in pigments in paints industries.

Used as mordants (fixatives) in dyeing.

Used in electroplating.

Copper is often used to color glass. It is also one component of ceramic glaze.

Some structures, such as the Statue of Liberty, are made with copper.

Copper is a great water-proof roofing material. It has been used for this purpose since
ancient times.

Used in refrigerators and air conditioning systems.

Copper is sometimes combined with nickel to make a corrosion resistant material that is
used in shipbuilding.
Apart from industrial use copper plays an important role in all organisms, including man. Copper
can be used as a pesticide as well as a nutrient. Copper is an essential nutrient with daily dietary
amounts of 1-2 mg requirement for adults. It is a natural anti plaque and anti bacterial agent. It is
a component of hemocyanin, the blue, oxygen-carrying blood pigment of lobsters and other large
crustaceans. Copper is needed for certain critical enzymes to function in the body.
2.3.2 HARMFUL EFFECTS OF COPPER
Copper is one of the toxic heavy metals, which has been reported to cause neurotoxicity
commonly known as “Wilson‟s disease” due to deposition of copper in the lenticular nucleus of
the brain and kidney failure (Banum, 1982). Moreover, continued inhalation of copper
23
containing sprays is linked to an increase in lung cancer among exposed workers. Excessive
intake of copper causes harmful biochemical effects, and it may cause hemolysis, hepatotoxic
and nephro toxic effects in human beings. Long-term exposure to copper can cause irritation of
the nose, mouth and eyes and it causes headaches, stomachaches, dizziness, vomiting and
diarrhoea. Copper toxicity leads to serve muscosal irritation, corrosion, widespread capillary
damage, hepatic and renal damage and nervous system irritation followed by depression
(Krishnamurthy and Vishwanathan, 1991).
2.3.3 SOURCES OF COPPER POLLUTION
Copper enters into the environment through natural and anthropogenic sources. The
contamination of air and water, by copper is contributed from the following sources:

Mining and metalurgy industries.

Electroplating industries.

Refining copper ores.

Milling.

Petroleum and refining.

Chloro-alkali industries

Industrial semlts namely iron and steel, fertilizer industies.

Explosives.

Battery manufacturing.

Copper –ammonium rayon industries and brass industries.
Copper is also discharged into the environment by natural source like windblown dust, volcanic
emissions, decaying vegetation, forest fire and sea sprays (Vilar, 2008).
2.3.4 DIFFERENT TECHNIQUES FOR COPPER REMOVAL
According to the WHO standards the maximum contamination level of copper is 1.3 mg L−1. The
majority of the industries are discharging effluents containing copper more than its permissible
limit. Thus the removal of copper from the industrial wastewater before releasing is necessary.
There are several convectional techniques available for the removal of copper ions from
wastewaters.
24

Chemical precipitation.

Ion -exchange.

Membrane filtration.

Electrochemical methods.

Biological methods.

Adsorption methods.
2.3.4.1 C HEMICAL PRECIPITATION
Fu et al., (2007) employed precipitation by 1,3,5-hexahydrotriazinedithiocarbamate to treat waste
water containing copper. They conducted experiments at different concentrations 25 mg/L, 50
mg/L, 100 mg/L and found the removal percentage to be 99.0%, 99.3%, and 99.6% respectively
at optimum pH 3. Chen et al., (2009) investigated the removal of copper using precipitation
process by lime precipitant. The percentage removal achieved was 99.37%- 99.6% at pH 7-11
respectively.
Pauline (2008) reported the removal efficiencies of copper from raw wastewater by
chemically enhanced primary treatment (CEPT). The removal was found to be 79%. They found
that the Enhanced coagulation and flocculation by ferric chloride and anionic polymer can
increase the dissolved metal removal efficiencies. Ngatenah et al., (2010) employed precipitation
to remove copper from aqueous solution using Groundwater Treatment Plant Sludge (GWTPS).
The optimum conditions to for 100% removal were found to be pH between pH 2 and pH 2.5,
contact time varied from 90 min to 480 min.
2.3.4.2 I ON - EXCHANGE
Erol and Turkan (2010) investigated the removal of copper from aqueous solution by ion exchange process using Lewatit CNP 80 resin (weakly acidic) and Lewatit TP 207 (weakly
acidic and chelating). They found the optimum pH range for the ion-exchange of copper on
Lewatit CNP 80 and Lewatit TP 207 were 7.0–9.0 and 4.5–5.5, respectively. Selvaraj et al.,
(2007) employed ion-exchange process to treat copper containing waste water by Amberjet
1500H and Ambersep 252H resins. From the adsorption isotherm studies they observed that the
25
uptake capacity of Cu (II) on 1500H is larger than that of 252H due to the intrinsic ion exchange
capacity, while the adsorbate/adsorbate interaction of 1500 is smaller than that of 252H.
Liu and Erhan (2001) used ion-exchange process to remove copper from aqueous
solution by Carboxylate-Containing Resin. They determined the cation exchange capacity of the
resins to be 3.50 m equiv/g. The maximum adsorption capacity of copper obtained on the resin at
pH5.0 was found to be 192 mg/g. Doula (2009) employed clinoptilolite - Fe system to remove
Cu, from drinking water. He found that the system has very large metal adsorption capacity and
for most of the cases the treated water samples were suitable for human consumption or
agricultural use. Dobrevsky et al., (1997) found that purification of galvanic wastewaters
containing on the average 55–60 mg Cu (II) dm-3, 140–150 mg SO2-4 dm-3 and of pH about 3.3–
3.5 can be successfully carried out by means of ion exchange method.
2.3.4.3 M EMBRANE FILTRATION
Camarilloa et al., (2010) employed ultrafiltration technique by polymer enhanced ultrafiltration
ceramic membrane to treat copper from wastewater. They found that the maximum removal
achived was 99.5% at optimum pH 5.5. Zhang et al., (2009) reported the use of reverse osmosis
process in removal of copper from aqueous solution. The maximum removal were found to be
70% - 95 % for initial metal concentration 20 mg/L-100 mg/L at Low pressure reverse osmosis
combined with electrowinning. Molinari et al., (2008) employed PEI as a polymer to study the
complexatione-ultrafiltration process in the removal of Cu(II) contained wastewater. From
preliminary tests they found that the optimal chemical conditions for Cu(II) complexation by the
PEI was pH > 6.0, and polymer/metal weight ratio as 3.0.
Yang and Kocherginsky (2007) investigated the use of hollow fibre supported liquid
membrane (HFSLM) system to remove copper from ammonical waste water. Based on the
empirical correlations they estimated that the overall mass transfer resistance through HFSLM is
higher than total of the element resistances in the tube side, shell side and the membrane.
Tanninen et al., (2006) studied removal of copper from waste water using Nanofiltration process
at 0.47 M initial metal concentration. They found the maximum removal up to 96%-98% at 20
bar. Hani and Hassan (2004) employed Reverse osmosis and Nanofiltration(NF) technique to
remove copper from aqueous solution. From the results they found that high removal efficiency
26
of the heavy metals could be achieved by RO process (98%). Through NF, up to 90% of the
copper ions were removed..
2.3.4.4 E LECTROCHEMICAL TECHNIQUES
Akbal and Camcı (2010)employed Electro-coagulation and Chemical Coagulation to remove
copper metal plating wastewater using electrolytic cell using aluminum or iron electrodes and
aluminum sulfate or ferric chloride respectively. They observed that chemical coagulation with
aluminum sulfate and ferric chloride dosage of 500, and electro-coagulation with iron electrodes
at a current density of 10mAcm–2, electro-coagulation time of 20 min, and pH 3.0 resulted in
99.9% copper removal. Escoba et al., (2006) investigated electro-coagulation process to remove
copper from natural waters and simulated wastewater using electrodes of commercial laminate
steel. They identified the optimum conditions for the process as pH 7, flow rate 6.3 cm3/ min and
a current density between 31 A/m2 and 54 A/m2and when the electrode geometric area and time
of electrolysis reached critical values, the copper removal reached a maximum value of 80%.
Akbal and Camcı (2010) reported the removal of copper from metal plating industry
using Fe- Al electrodes. They found from the results that electrocoagulation with a Fe–Al
electrode pair efficiently removed 100% Cu, at an electrocoagulation time of 20min, a current
density of 10mA/cm2 and at pH 3.0. Khelifa et al., 2005 employed electro coagulation process to
treat copper from aqueous solution. The optimum conditions for the maximum Cu removal
(99%) was pH 6 and current density 0.3A. Chang et al. (2009a) used electrodeposition process in
conjunction with ultrasound to remove copper from wastewater. They found that the technique
can successfully remove copper (95.6%) from wastewater.
2.3.4.5 B IOLOGICAL METHODS
Gupta et al., (2006) investigated bisorption of copper aqueous solutions by green alga Spirogyra
species. They observed the maximum biosorption capacity of 133.3 mg Cu(II)/g of dry weight of
biomass at an optimum pH of 5 in 120 min with an algal dose of 20 g/L. Hossain and
Anantharaman (2005) employed bisorption of copper by Thiobacillus ferrooxidans. They found
the maximum biosorption of copper to be 94.25% within 60 hr of inoculation time with optimum
pH 4.5 and temperature 40◦C for 700ppm initial copper loading. Narsi et al., (2004) used the
dead biomass of spirogyra species, for the removal of copper from aqueous solution. It was
27
observed that the spirogyra species shown much better sportion in the pH between 6-7 and at
contact time of 30 min. The maximum uptake found was 34.94mg/g.
Pairat (2002) employed biosorption of copper using biomass of marine algae as an
adsorbent. He found that the sorption capacities were solution pH dependent and the maximum
capacity obtained was 0.80 mmol/g at a solution pH 5. The biosorption kinetics was found to be
fast; with 90% of adsorption within 15 min and equilibrium reached at 30 min. Muraleedharan
and Venkobachar (1990) reported the use of G. lucidum as biosorbent to remove copper from
aqueous solution.
2.3.4.6 A DSORPTION
Gaikwad (2011) employed adsorption process to remove copper from wastewater using activated
carbon derived from coconut shell. From the results he found that the adsorption follows first
order kinetics and is slightly endothermic. Zhao et al., (2010) investigated the adsorption of
copper onto bentonite embedded in the polyacrylamide (PAAm) gels from aqueous solution.
They observed that the sorption increased from about 9% to 97% at pH ranging from 2.4 to 7 and
sorption capacity was found to be 33mg/g. Ghassabzadeh et al., (2010) employed adsorption
process to remove copper from aqueous solution on to expanded perlite (EP). The optimum
conditions for adsorption of copper were found to be pH 6.5 and 240 min contact time. Using the
Langmuir model equation, they found the maximum adsorption capacity of EP to be 1.95 mg/g.
Yao et al., (2010) employed batch adsorption studies to remove copper from aqueous
solution by chestnut shell. They observed that the adsorption was pH dependent and there was a
sharp increase in the copper removal from 20.4% to 92.4% occurred when the pH values of the
solutions changed from 2.0 to 5.0. Jaman et al., (2009) used rice husk as a low cost adsorbent for
the removal of copper from wastewater. From the experimental results they observed that almost
90–98% of the copper could be removed using treated rice husk. They found the results that the
adsorption equilibrium data fitted the Langmuir adsorption model very well at different
temperatures. Tariq et al., (2009) employed adsorption of copper from aqueous solution on to
pine fruit a solid adsorbent. From the results they found that the adsorption was pH dependent
the optimum pH for the removal Cu+2 was 7.0, the highest adsorption capacity was found to be
14.1 mg of metal ion per gram of adsorbent at initial concentration of 57.6 mg/L and copper ions.
28
The percentage removal was found to be 94.1-96% along the whole range of initial
concentrations.
Rathnakumar et al., (2009) reported the use of Teak (Tectona grandis L.f) Leaves as an
adsorbent to remove copper from aqueous solution. They carried ou experiments at various
initial concentrations of Cu (II) (i.e. 0.2 g L-1, 0.4 g L-1, 0.6 g L-1, and 0.9 g L-1), biosorbent
dosages (0.3 g L-1, 0.4 g L-1, and 0.5 g L-1), pH (4, 5 and 6) and temperature (20◦ C, 30◦C, and
40◦C). From the results they found that the maximum percentage removal was achived at pH 6
and at a temperature of 20◦C. Haluk Aydına et al 2008. investigated adsorption of copper from
aqueous solution by different adsorbents such as shells of lentil (LS), wheat (WS), and rice (RS).
They found the maximum adsorption capacities for Cu (II) on LS, WS and RS adsorbents at 293,
313 and 333K temperature to be 8.977, 9.510, and 9.588; 7.391, 16.077, and 17.422; 1.854,
2.314, and 2.954mg g-1, respectively. Benaïssa and Elouchdi (2007) used dried sunflower leaves
as adsorbent to remove copper ions from aqueous solutions. The maximum copper sorption was
found to occur at around initial pH 5–6 and the maximum copper uptake was fond to be obtained
was qm = 89.37 mg/g (1.41 mmol/g).
Kadirvelu et al.,(2001) reported adsorption of copper from industrial wastewaters onto
activated carbon prepared from an agricultural solid waste. They observed that the maximum
removal was achieved at pH 4. Yu et al.,(2000) employed adsorption of copper from aqueous
solution using saw dust as an adsorbent. They found that adsorption of copper is dependent on its
initial concentrations, the amount of sawdust, time of contact and pH of the metal solution. The
maximum removal of copper on sawdust was obtained at pH 7.0. The adsorption capacity of
sawdust for copper was 1.79 mg/g. Teker and İmamoğlu (1999) investigated adsorption of
copper (II) from aqueous solutions,on activated carbon prepared from rice hulls (ACRH). They
found that the maximum removal was achived at optimum values of pH, ACRH dosage and
contact time were determined to be 5-8, 0.5 g ACRH/25 mL solution an 60 minutes respectively.
Apart from batch studies, adsorption process are also carried out in in different
continuous column, which helped in scaling up the laboratory/bench scale data to pilot or
industrial scale. The main necessity of an industrial adsorption system is that the adsorbent be
29
utilized in a fixed or expanded bed with as low a pressure drop as possible. In these process
applications, a packed bed column is an effective process for cyclic sorption/desorption, as it
makes the most tremendous use of the concentration difference known to be a driving force for
heavy metal sorption and results in a improved qualityof the effluent.
Aguayo-Villarreal et al., (2011) employed column adsorption studies for removal of zinc
from aqueous solution using chicken feathers an adsorbent. They observed from the results that
the characteristics of the breakthrough curves are dependent of the column operating conditions
especially pH and feed flow rate. Helen et al., (2010) reported the adsorption behaviour of Ni
and Zn from aqueous systems onto activated carbon prepared from Hevea brasiliensis sawdust
column mode studies under different operating conditions. It was observed from the results that
the adsorption capacity increased with increase in the initial metal ion concentration and
decreased adsorption capacity with flow rate for both the metals. They also observed that the
adsorption capacity comparatively remained constant with bed height which shows that it is
independent of bed height.
Pereira et al, 2009 investigated adsorption of zinc from electroplating wastewater using
column experiments onto modified wood sawdust and sugarcane begasse. From the results the
maximum adsorption capacities Qmax were found to be 46 and 60 mg/g, for MB2 and MS2,
respectively. The regeneration process of the column proved to be efficient for both adsorbents
MS2 and MB2, confirming the ablity of these materials for removing and recuperating Zn2+ ions
from electroplating wastewater. Doan et al.,(2008) tested adsorption capacity of wheat straw in
removal of zinc and nickel using fixed bed column. From the results they found that the amount
of metal ions adsorbed and the adsorption rate of both Zn+2 and Ni+2 generally increased with the
liquid pH from 4.0 to 7.0 and when temperature increased from 30 to 35ºC.
Vijayaraghavan et al., (2004) investigated the ability of crab shell to remove nickel (II)
ions from aqueous solution using a packed bed up-flow column. They conducted experiments at
different bed heights (15–25 cm) and using different flow rates (5–20 ml/min) in order to obtain
experimental breakthrough curves. From the results it was found that the elution efficiency was
greater than 99.1% in all the seven cycles. Wilson et al., (2001) employed column adsorption
studies to remove zinc from contaminated water onto bone charcoal.
30
2.4 SCOPE OF PRECENT WORK .
The literature review outlines that heavy metal pollution is one of the serious issues in the
present scenario. In order to solve this problem there is a need for low-cost process which can be
used with ease. One such type of process is adsorption process which is accepted universally as
the latest method of treating industrial/mine wastewater for removal of soluble toxic components
and is simple and convenient in operating.
Generally many adsorbents have been employed for the removal of heavy metals, which
have shown high removal efficiency. But there is a scope for further research to explore new
materials which are low cost. In this regard Sponge Iron plant waste (SIP) which is an industrial
waste is considered to be one of the low cost materials.
In the present work, an attempt was made to removal of Zinc, Nickel, and Copper from
aqueous solution onto HCl treated SIP waste using both batch and column techniques.
The SIP waste was treated with HCl to increase the adsorption capacity. The physical
and-chemical properties before and after treatment of the adsorbent were analyzed. The
adsorption capacity was studied as a function of contact time, adsorbent dose, pH, initial metal
concentration, temperature for all the three metals. Different adsorption isotherm models were
employed in order to estimate the optimum adsorption conditions. Different Kinetic models were
also studied to now the rate controlling mechanism of the process. Thermodynamic parameters
such as standard Gibbs energy (G°), enthalpy (H°), and standard entropy (S°) were calculated for
each process using the experimental data. Continuous column experiments were carried at
different bed heights and flow rates at optimum pH. The results obtained were well compared
with
the
results
reported
by
other
adsorbents
in
the
literature.
31
3 MATERIALS AND METHODS
3.1 PREPARATION OF ADSORBENT
Sponge iron plant waste form a local sponge iron industry, Mahavir Fero Pvt. Ltd., situated at
Kalunga was collected. The collected sample was pulverized to pass through a set of sieves
according to the ASTM Method D 2013 and was dried in an oven at 100 ± 5◦C for 24 hr. It was
then subjected to surface modification process by soaking in HCl, which increases the proportion
of active surface (Argun et al., 2007). The oven dried adsorbent was washed several times with
distilled water, to remove any particles adhering to the surface. The dried adsorbent was added to
500ml conical flask containing 250 ml of 1N HCl solution. The mixture was left overnight and
filtered to remove the sorbent, followed by washing several times with distilled water to make it
neutral. The adsorbent is again dried at an oven temperature of 85◦C for 2hr.
3.2 CHARACTERIZATION OF ADSORBENT
3.2.1 PHYSICAL PARAMETERS
3.2.1.1 M OISTURE ANALYSIS
The moisture analysis of the SIP waste was studied using standard ASTM Method D 3173. The
adsorbent was dried in a hot air oven at 110ºC for 1h. The percentage moisture was then
calculated using the following equation:
Moisture in analysis sample ,%   A  B  / A 100
(1)
Where: A = grams of sample, and
B = grams of sample after heating.
3.2.1.2 V OLATILE MATTER ANALYSIS
32
Volatile matter in the SIP waste was determined using ASTM standard Test Method D 3175. The
sample was heated for 7 min at 950ºC in preheated muffle furnace. The volatile matter was then
calculated the following equations:
Weight loss ,%   A  B  / A 100
(2)
Where: A = weight of sample used, g, and
B = weight of sample after heating, g
Volatile matter in analysis sample ,%  C  D
(3)
Where: C = weight loss, %, and
D = moisture, %.
3.2.1.3 A SH CONTENT ANALYSIS
Ash content in the SIP waste was determined using ASTM standard Test Method D 3174. The
sample was heated in a muffle furnace for 4h at 750◦C. The Ash content was calculated using the
following equations:
Ash in analysis sample ,%   A  B  / C  100
(4)
Where: A = weight of capsule, cover, and ash residue, g,
B = weight of empty capsule and cover, g, and
C = weight of analysis sample used, g.
3.2.1.4 I ODINE NUMBER
Iodine number of the SIP waste was determined using standard ASTM Test Method D 4067. The
sample was added to 100mL of 0.100 N iodine solution and shacked vigorously for 30 ±1 s and
filtered. The filtrate was then titrated with standardized 0.100 N sodium-thiosulfate solution until
the solution was a pale yellow. 2 mL of the starch indicator solution was added and titrated with
sodium thiosulfate until colorless solution was obtained. Iodine number was calculated by the
formula given below.
33
M  A  DF C 126.9350  / E
(5)
Where: M = carbon, g,
A = (N2) (12693.0),
N2 = iodine, N
DF = dilution factor
C = residual iodine, and
E = estimated iodine number of the carbon.
3.2.1.5 A NALYSIS OF SPECIFIC SURFACE AREA
The specific surface area of the powder was analyzed by nitrogen adsorption at 77 K in BET
surface analyser (Quanta Chrom-USA). Degassing at 200◦C for 2 h was performed prior to
measurement.
3.2.1.6 Z ETA POTENTIAL
The zeta potential of the adsorbent was obtained by analysis in different pH by using an
equilibrium method in batch system (Smiciklas et al., 2000). 200mg of adsorbent was added to
20mL sodium chloride 0.1mol/L with pH adjusted among 1 and 12. The samples were stirred for
1h at room temperature (about 25 C), and the final pH was measured.
3.2.2 CHEMICAL PROPERTIES
3.2.2.1 FTIR ANALYSIS
The organic functional groups present in the SIP waste were determined using FTIR analysis.
The analysis was carried out using FTIR-3500 spectrophotometer. For measuring the absorption
spectra pellets (press disk) were used. The samples were ground along with 200 mg of KBr
(spectroscopic grade) in a mortar and pressed into 10 mm diameter disks less than 10 tons of
pressure and high vacuum, and 16 scans at a resolution of 4 cm-1 measured between 600 - 4000
cm-1 were used.
3.2.2.2 S CANNING E LECTRON M ICROSCOPE (SEM) ANALYSIS
34
The SIP before and after were analysed using SEM/EDX (SEM - JEOL, JSM 6480 LV) at
1000X magnification. From SEM analysis the surface texture is known. EDX gives the
elemental analysis.
3.3 CHEMICALS
All the chemicals used were of analytical reagent grade. Zinc metal, nickel chloride, and copper
sulphite were used for preparation of stock solutions. Hydrochloric acid and Sodium hydroxide
were used to adjust the solution pH. Distilled water was used throughout the experimental
studies.
3.4 STOCK SOLUTION PREPARATION
Stock zinc solution (100mg/L) was prepared by dissolving 100 mg zinc dust power in a slight
excess of 1+1 HCl and diluted to 1000ml with distilled water. Stock solution of 1000 mg/l Cu
(II) ion is prepared dissolving copper sulphate pentahydrate (CuSO4.5H2O) purchased from
MERK India Ltd in water. To do this 3.772gm CuSO4.5H2O is added in distill water contained
in 1000ml volumetric. Stock solution of 1000mg/L Ni (II) ion is prepared by dissolving Nickel
chloride punched from MERK India Ltd in water. To do this 3.246g NiCl2.6H2O is added in
distill water contained in 1000ml volumetric
3.5 INSTRUMENTATION
The list of the instruments used during the adsorption experiments and there functions are given
in the Table 1
TABLE 3.1: List of Instruments
Instruments
Analytical Balance
pH meter
BET apparatus
Ultra-pure water system
Atomic Absorption
spectrophotometer
Shaker
Makers
Sartorius
EuTech Instruments
Quanta Chrom-USA
Sartorius
Function
Weight Measurement
Measurement of pH
Surface area of the adsorbent
Preparation of the stock solution,
throughout the experiment etc.
A Analyst 200, Perkin Estimation
of
metal
ion
Elmer
concentration
Lab Companion model SI- Batch adsorption studies of heavy
300R
metals
35
Perkin Elmer, resolution on
4cm-1
SEM - JEOL, JSM 6480
LV.
FTIR
SEM-EDX
Analyze the organic functional
groups present in the adsorbent
Surface texture and Elemental
analysis of sample
3.6 ADSORPTION EXPERIMENT
Batch adsorption experiments were carried out in a shaker at room temperature using a series of
conical flasks containing desired dose of adsorbent in a predetermined concentration of zinc,
nickel and copper metal solutions for a fixed duration. Samples were collected at different time
interval. The supernatant was separated by filtration and analyzed through AAS to estimate the
metal ion concentration. Experiments were carried out at different initial pH values. The initial
pH of the solution was adjusted with either HCl or NaOH. The percent removal of metals from
the solution was calculated by the following equation.
%removal 
C0  Ce
 100
C0
(6)
Where C0 (mg/L) is the initial metal ion concentration and Ci (mg/L) is the final metal ion
concentration in the solution. Isotherm studies were recorded by varying the initial concentration
of metal solution from 10 to 100 mg/L. A known amount of adsorbent was then added into the
solutions followed by agitating the mixture at 120 rpm till equilibrium. The amount of the metal
uptake was calculated by the difference between the equilibrium concentration and the initial
concentration. The amount of metal retained in the solid phase qe (mg/g) was calculated using the
relation:
qe 
(C0  Ce )V
m
(7)
Where m is the mass of adsorbent (g), V is the volume of the solution (L), C0 is the initial
concentration of metal (mg L-1), Ce is the equilibrium metal concentration (mg L-1) and qe is the
metal quantity adsorbed at equilibrium (mg/g).
3.7 ADSORPTION ISOTHERMS
36
Adsorption isotherm helps in determining the properties of the adsorbents. The isotherm curve
can be employed to achieve information about the desorption mechanism that is connected with
interaction between the adsorbent and adsorbate molecules. Therefore, these curves are used in
determining the effectiveness of an industrial adsorbent. The correct description of experimental
adsorption isotherm can be understood in terms of some mathematical equations called
adsorption isotherm model equations. These equations are derived assuming an ideal physical
model for the adsorption system. The model assumptions are generally a result of experimental
observations. The performance in a full scale process stream can be estimated using adsorption
isotherm. They help to determine, the possibility to attain a required purity level for a given
adsorbent. This is important when multiple impurities are present and one or more impurities are
weakly adsorbed. The isotherm also allows calculation of uptake (qe) at equilibrium, which has a
main impact on the process economy. It can also be used to calculate the relative performance of
different types of adsorbents.
Some of the isotherm models in regular use are:

Langmuir isotherm model.

Freundlich isotherm model.

Dubinin-Radushkviech (D-R) isotherm model.

Temkin isotherm model.
The study of the adsorption equilibrium was carried out for metal concentrations varying from 10
to 100mgL-1.
3.7.1 LANGMUIR ISOTHERM MODEL
The Langmuir adsorption isotherm (Langmuir, I., 1918) was based on the following
assumptions:
 Fixed number of adsorption sites: at equilibrium, at any temperature, a fraction of the
adsorbent surface sites (θ) is occupied by adsorbed molecules and the rest (1- θ) is free.
 All sorption processes are homogeneous.
 There is only one sorbate.
 One sorbate molecule reacts with only one active site.
 No interaction between the sorbate species.
 A monolayer surface phase is formed.
37
The equation proposed by Langmuir was generally applicable to chemisorptions with some
limitations involving physical adsorption. With one category of adsorption active centre this
equation is applicable to the physical or chemical adsorption on solid surface. As long as its
restrictions and limitations are clearly known, the Langmuir equation can be used for describing
equilibrium conditions for sorption behaviour in different sorbate-sorbent systems or for diverse
conditions within any given system. The Langmuir equation is given by:
qe 
qm K L Ce
1  K L Ce
(8)
The linearization of it leads to the following form:
Ce
C
1

 e
qe q m K L q m
(9)
Where Ce, equilibrium metal concentration, qm and KL are the Langmuir constants related to
maximum adsorption capacity (mg/g), and the relative energy of adsorption (1/mg), respectively.
The essential characteristics of Langmuir isotherm model can be explained in terms of a
dimensionless constant separation factor, RL, defined by:
RL 
1
1  K L C0
(10)
The values of RL indicates the type of Langmuir isotherm to irreversible (RL=0), favorable
(0<RL<1), linear (RL=1) or unfavorable (RL>1).
3.7.2 FREUNDLICH ISOTHERM MODEL
Freundlich equation is derived to model the multilayer adsorption and for the adsorption on
heterogeneous surfaces. It is based on the assumption that an exponential distribution of
adsorption energies exists for each component.
The Freundlich equation is given by (Freundlich and Heller, 1939):
qe  K F C
1
n
e
(11)
38
The logarithmic form of equation:
ln qe  ln K F 
1
ln C e
n
(12)
Where qe is the amount of metal ion adsorbed per specific amount of adsorbent (mg/g), Ce is
equilibrium concentration (mg/L),KF and n are freundlich equilibrium constants.
3.7.3 DUBININ –RADUSHKEVICH ISOTHERM
The D-R isotherm is more general than the Langmuir isotherm, because it does not assume a
homogeneous surface or constant sorption potential. The D-R equation is:
qe  q m e


 1

   RT ln  1

 Ce


2
  
 
 
  
(13)
The linear form of this model is expressed by (Peric et al., 2004):
ln qe  ln qm   2
(14)
Where β is a constant related to the adsorption energy, R (8.314 Jmol−1 K−1) is the gas constant,
and T (K) is the absolute temperature; and ε = RT ln (1 + 1/Ce). The constant β (mol2 KJ−2)
reflects the mean free energy E (KJ mol−1) of sorption per molecule of the adsorbate when it is
transferred to the surface of the solid from infinity in the solution and can be computed using the
relationship.
E  2 
1 / 2
(15)
This parameter gives information about chemical or physical adsorption. With the magnitude of
E, between 8 and 16 KJ mol−1, the adsorption process follows chemical ion-exchange, while for
the values of E< 8KJmol−1, the adsorption process is of a physical nature.
3.7.4 TEMKIN ISOTHERM
Temkin isotherm includes a factor that clearly takes in account the interactions between
adsorbing species- adsorbate. This isotherm assumes that decrease in the heat of adsorption is
39
linear and the adsorption is characterized by a uniform distribution of binding energies. Temkin
isotherm is given by the following equation (Temkin and Pyzhev, 1940):
qe 
RT
ln aC e 
b
(16)
Linear form of Temkin isotherm is given by the following equation:
qe  a  b ln Ce
(17)
Where q e is the amount of metal ion adsorbed per specific amount of adsorbent (mg/g), C e is
equilibrium concentration (mg/L), a is equilibrium binding constant (g-1) and b is related to heat
of adsorption (J/ mol) which are Temkin constants.
3.8 ADSORPTION KINETICS MODEL
The study of adsorption kinetics in wastewater is important as it afford important insight into the
reaction pathways and into the mechanism of the reaction. Further, it is important to predict the
time at which the adsorbate is removed from aqueous solution in order to design a proper
sorption treatment plant. Any adsorption process is normally controlled by three diffusive
transport processes for the adsorbate:

From bulk solution to the film surrounding the adsorbent.

From the film to the adsorbent surface

From the surface to the internal sites followed by binding of the metal ions onto the
active sites.
However, in kinetic modeling all these three steps are assembled together and it is believed that
the difference between the average solid phase concentration and equilibrium concentration is
the driving force for adsorption. Further, it is recognized from the experimental observations that
at optimum agitation speed, the external boundaries have no significant effect. Therefore
application of the kinetic model depends only on the initial and final concentrations of the
solution at different time intervals. It is inaccurate to apply simple kinetic model such as first and
second order rate equations to a sorption process with solid surface, which is rarely homogenous.
On the other hand, the effects of transport and chemical reaction are often experimentally
40
inseparable. Numerous kinetic models have been proposed to explain the mechanism of a solute
sorption from aqueous solution onto an adsorbent:
 Pseudo first order/Lagergren kinetic model.
 Pseudo second order kinetic model.
3.8.1 PSEUDO-FIRST ORDER MODEL
The Pseudo first order or Lagergen kinetic rate equation for the sorption of liquid-solid system
was derived based on solid adsorption capacity. It is one of the most extensively used sorption
rate equations for sorption of a solute from a liquid solution. Lagergren equation is given by the
following equation (Ho and McKay, 1999a):
dq
 k1 qe  qt 
dt
(18)
Where k1 (min−1) is the rate constant of the pseudo-first-order adsorption, qt (mg/g) denotes the
amount of adsorption at time t (min) and qe (mg/g) is the amount of adsorption at equilibrium.
After definite integration by application of the conditions qt =0 at t = 0 and qt = qt at t = t, Eq.
(13) becomes.
 k 
log qe  qt   log qe   1 t
 2.303 
(19)
The adsorption rate constant, k1, can be calculated by plotting log (qe −qt) versus t.
3.8.2 PSEUDO-SECOND ORDER MODEL
The pseudo-second-order equation can be written as (McKay and Ho, 1999 b,c):
dq
2
 k 2 qe  qt 
dt
(20)
Integration of Eq. (15) and application of the conditions qt =0 at t = 0 and qt = qt at t = t, gives
t
1
t


2
qt
qe
k 2 qe


(21)
Where k2 (g/(mg min)) is the rate constant, k2 and qe can be obtained from the intercept and
slope.
41
3.9 ADSORPTION MECHANISM
The adsorption process for porous solid can be divided into three phases i.e. (a) mass transfer
(boundary layer/film diffusion), (b) sorption of ions on to sites and (c) intra-particle diffusion. In
various cases there is a possibility that intra-particle diffusion will be the rate-limiting step and is
given by (Weber et al., 1963).
qt  kid t 1 / 2
(22)
The plot between qt vs. t1/2 gives the values of coefficient of intra particle diffusion (kid) for
adsorption parameter. And the plot between time (t) vs. adsorption percentage at different
adsorption parameters may not be linear over the total time range. In that case, more than one
step may affect the adsorption process. Therefore the adsorption process can be divided into two
different steps, the initial curved portion relates to film diffusion (D1) and the latter linear portion
relates to the diffusion within the adsorbent. If film diffusion is the rate-controlling step, the
value of film diffusion co-efficient (D1) should be in the range 10-6 -10-8 cm2s-1. The equation for
„D1‟ and „D2‟ are given by (Crank, 1975).
1/ 2
qt
 D 
 6 12 
qe
 a 
t 1/ 2
2
 qt 
 6   D2 t 


ln 1    ln  2    2 
   a 
 qe 
(23)
(24)
„D1‟ can be calculated from the slope of the plot between qt/qe vs. t1/2 for the initial curved
portion. „D2‟ can be calculated from the slope of the curve between ln (1- qt/qe) vs.„t‟.
3.10 THERMODYNAMIC PARAMETERS
Temperature dependence of the adsorption process is related with several thermodynamic
parameters. Thermodynamic parameters can be determined using the equilibrium constant K
(qe/ce). The change in Gibbs free energy (∆G◦), enthalpy (∆H◦) and entropy (∆S◦) associated to
the adsorption process was calculated using the following equations (Azouaoua, 2010):
G  RT ln K
(25)
Where K= Langmuir constant
42
T = absolute temperature (oK)
R = universal gas constant (8.314 Jmol−1 K−1)
ln K 
S  H 

R
RT
(26)
∆H◦, ∆S◦ can be calculated from the slope and intercept of the vant Hoff‟s plot of ln K vs. 1/T
respectively
3.11 FIXED BED ADSORPTION STUDIES
Continuous adsorption studies were conducted using a Perspex fixed bed column of 3cm ID and
40 cm length. An adjustable plunger with a 250µm sieve was attached at the top of the column is
place. At the top of the column, an adjustable plunger was attached with a 0.5mm stainless sieve
another sieve of 250µm was placed in the bottom of the column to support the packing. A known
quantity of SIP waste was filled in the column. The effects of bed height, flow rate were studied.
The metal solution was fed to column at a constant flow rate from bottom to top using a
peristaltic pump. The samples were collected from the top of the column at various time intervals
and were analyzed for Zn and Ni ions using atomic absorption spectrophotometer.
43
Figure 3.1: Fixed bed column used for the column adsorption studies.
3.12 ANALYSIS OF COLUMN DATA
As the metal solution passes through the column gradually with time the adsorption sites were
filled with metal ions and slowly the adsorption zone (where the bulk of adsorption takes place)
starts moving up of the column and the effluent concentration start rising with time as the metal
solution passes through column. The point at which the concentration of metal in the effluent has
suddenly risen to an appreciable value i.e., 1mg/L for the first time is called break point. The
time at which the break point is reached is called break through time (tb) and the portion of the
effluent concentration curve as a function of time is called break through curve. The time at
which metal concentration in the effluent go beyond 99% of the inlet concentration is called bed
exhaustion time (te) (Treybal, 1981).
44
The column adsorption capacity was calculated using the Eq. (27) and is expressed in mg of
metal ion adsorbed per gram of adsorbent:
Q
mad
M
(27)
Where mad is the quantity of metal ion retained in the column (mg) and M is the mass of the SIP
waste (g). mad is obtained by multiplying the area above the breakthrough curve and the flow
rate:
mad  Fa
(28)
Where F is the flow rate (L h−1) and „a‟ is the area above the breakthrough curve (Ct versus t),
obtained through numerical integration (Volesky and Prasetyo, 1994).
The total amount of metal ion sent to the column (mtotal) is calculated from Eq. (29):
mtotal  C0 Fte
(29)
Where C0 is the initial metal ion concentration (mg L−1) and te is the bed exhaustion time (h).
Total metal removal is calculated from Eq. (30):
Metal Re moval (%) 
mad
 100
mtotal
(30)
The mass transfer zone ( t ) given by Eq. (31)
t  te  tb
(31)
The critical bed height which is also termed as the height of the mass transfer zone (Z m) is
related to bed height, breakthrough and exhaustion times (Volesky, 2003) and is determined
using Eq. (32):
Z m  Z 1  te  tb 
(32)
45
Effluent volume (Veff) was calculated by using Eq. (33), ( Aksu and Gonen, 2003):
Veff  Fte
(33)
3.13 MODELING OF BREAKTHROUGH CURVE
The breakthrough curve helps in calculating the performance of a packed bed reactor. The
dynamic response of an adsorption column can be determined by the characteristics like time for
breakthrough appearance and the shape of the breakthrough curve. The successful design of a
column adsorption process requires prediction of the concentration-time profile or breakthrough
curve for the effluent. The metal adsorption over different adsorbents is illustrated by many
mathematical models. The design of the adsorption process is based on the exact generation of
breakthrough curves. The flow rate of the feed solution, concentration of metal ions in the feed,
bed height and temperature affect the breakthrough time, exhaustion time and adsorption
capacity of the bed. The dynamic behaviour of the fixed bed column was calculated by using
Thomas model in the present studied.
3.13.1
THOMAS MODEL
The Thomas model is one of most general and widely used methods in column performance
theory. The Thomas model, which assumes Langmuir kinetics of adsorption–desorption and no
axial dispersion derived with the adsorption such that the rate driving force obeys second order
reversible reaction kinetics. The expression using the Thomas model for adsorption column is
given as Eq (34) (Aksu, and. Gonen, 2004).
C
 k q m kTh C0Veff
ln  0  1  Th 0 
Q
Q
 Ct

(34)
Where „KTh‟ is the Thomas rate constant (mL/mg min), „q0‟ is the equilibrium adsorbate uptake
(mg/g) and „m‟ is the amount of adsorbent in the column.
46
4 RESULTS AND DISCUSSION- BATCH
ADSORPTION
4.1 CHARACTERIZATION OF ADSORBENT
4.1.1 PHYSICAL PROPERTIES
The physical properties of the adsorbent before and after the acid treatment were determined
using Eqs: (1), (3), (4), (5) and the values are presented in Table 4.1. The results clearly indicate
an increase in the available surface area of the adsorbent.
TABLE 4.1: Characteristics of untreated and HCl treated SIP waste.
Property
Moisture (%)
Volatile matter (%)
Ash content (%)
Fixed Carbon (%)
pHPZC
Iodine no(mg/g)
BET surface area (m2/g)
Untreated SIP waste
2.49
1.9
69.9
25.71
-141
118.5
HCl treated SIP waste
2.46
1.85
60.2
35.49
7.2
145
143.3
4.1.2 CHEMICAL PROPERTIES
4.1.2.1 FTIR ANALYSIS
The FTIR results for both HCl treated and untreated SIP waste were presented in figures 4.1(a)
& (b). It was observed that the acid treatment process did not affect the contentedness of
functional groups in the adsorbent. The four major peak ranges were almost unchanged before
and after the treatment. The peaks in the ranges 1000-1300cm-1 and 1600-1750cm-1 is attributed
to the C-O and C=O of esters and ketones groups respectively. A very broad band near to the
3600cm-1 indicates the presence of hydrogen bonded OH group which is due to the adsorption of
water on the adsorbent (Azouaoua et al., 2010; Vinke 1994).The peaks near to 2300cm-1 are
attributed to the presence of nitrile (C≡N) groups to some extent. The presence of C=O shows
47
very high affinity towards metal adsorption (Chen et al., 2002), that reflects the sorption capacity
of the adsorbent.
Figure 4.1: FTIR Spectrum of (a) Untreated SIP waste. (b) HCl treated SIP waste.
4.1.2.2 A NALYSIS OF SIP WASTE BY SEM/EDX
Scanning electron microscopic photographs of SIP waste and impregnated SIP waste illustrated
the figure 4.2 reveal the structure and indicates that the adsorbents had a porous and
homogeneous structure with a deep pore. A progressive change in the surface of the particles had
been observed (fig 4.2(a) & 4.2(b).)
(a)
(b)
Figure 4.2: SEM analysis of (a) untreated and (b) HCl treated SIP Waste.
The energy dispersive X-ray microanalysis of both the samples was shown in Table 4.2. It
indicates the presence of carbon and oxygen in larger percentage with other metals such as Al, Si
and Fe etc.
48
TABLE 4.2: Elemental composition of adsorbents.
Elements
C
SIP waste (wt %)
53.06
Impregnated SIP waste (wt
67.37
%)
O
31.61
Al
2.36
Si
3.67
Fe
7.16
S
0.68
19.79
3.31
5.31
1.18
--
4.2 BATCH ADSORPTION STUDIES
4.2.1 ZINC
4.2.1.1 E FFECT OF PARAMETERS
4.2.1.1.1 E FFECT OF CONTACT TIME
Effect of contact time is one of the important parameter in adsorption process. To determine the
effect of contact time on adsorption of zinc ions, adsorption experiments were conducting by
varying the contact time between the adsorbate and adsorbent in the range of 1–34 min. The
concentration of metal ions was 20mg/L, pH was kept as 5.0, and temperature 30◦C, while the
amount of SIP waste added was 1g/L. From Figure 4.3 the plot depicts that the rate of percent
removal of zinc was higher at the beginning. This may be due to the larger surface area of the
adsorbent being available at beginning for the adsorption of zinc ions. The HCl treated SIP waste
has shown higher percentage removal when compared with Untreated SIP waste. Equilibrium
adsorption was reached within a short span of around 26 min indicating that the adsorption sites
are well exposed (Orumwense 1996). It is clear for the results that the adsorption of zinc was
dependent on contact time. Based on these results, the shacking time was fixed at 26min and HCl
treated SIP waste as an adsorbent for rest of the experiments.
49
Figure 4.3: Effect of contact time on zinc adsorption using untreated SIP waste,HCl treated SIP
waste
4.2.1.1.2 E FFECT OF A DSORBENT DOSE
Effect of SIP waste on Zinc adsorption was studied at 20mg/L, 30◦C, and pH 6. The results of
adsorbent dose on the percentage removal of Zn metal on SIP waste is reflected in Fig 4.4.
Initially the metal uptake increased with adsorbent dose 0.1g/L to 1.5g/L and reached
equilibrium at 1g/L. It is due to increased adsorbent surface area and availability of more
adsorption sites (Cay et al, 2004). But at 1.5g/L adsorbent dose the metal ions adsorbed per unit
weight of adsorbent decreased which is due to the fact that at higher adsorbent dose the solution
ion concentration drops to a lower value of q indicating the adsorption sites to remain
unsaturated (Amarasinghi and Williams, 2007). Based on these results 1g/L was taken as
optimum adsorbent dose for the rest experiments.
Figure 4.4: Effect of Adsorbent Dose on Zn adsorption.
4.2.1.1.3 E FFECT OF P H
The pH of solution has significant impact on the uptake of metals, since it determines the surface
charge of the adsorbent, the degree of ionization and specification of the adsorbent (ElAshtoukhy et al., 2008). The variation of pH affects the effectiveness as hydrogen ion itself is a
tough competing adsorbate. Zinc ions exist in different forms in aqueous solution and the
stability of these forms is dependent of the pH of system.
50
The effect of pH on adsorption of zinc is shown in Fig.4.5. The effect of pH on
adsorption of zinc was studied at 30◦C, initial metal concentration 20mg/L, adsorbent dose 1g/L
by varying the pH of metal solution from 2-7. The percentage adsorption increases with increase
in pH. The minimum adsorption was observed at low pH may be due the fact that the presence of
higher concentration and higher mobility of H+ ions favoured adsorption compared to M (II) on
the other hand in the acidic medium due to high solubility and ionization of metal ions. The
surface of the adsorbent becomes more positively charged at high H+ concentration such that the
attraction between adsorbents and metal cations is reduced. In reverse with increase in pH the
negatively charged surface area becomes more thus facilitating grater metal removal. The
maximum adsorption was observed within the pH range 4 to 7 which might be due to partial
hydrolysis of metal ions (Onundi et al., 2010). Further increase in pH i.e., above 7 of the solution
causes precipitation of zinc ions on the surface of the adsorbent by nucleation (Agrawal et al,
2004; Inbaraj and Sulochana, 2006). From these results it was clear that at pH 7 the metal uptake
was more i.e., 59.25% based on this pH 7 was taken has optimum pH for rest of the experiments.
Figure 4.5: Effect of pH on percentage removal of zinc on SIP waste.
4.2.1.1.4 E FFECT OF INITIAL METAL CONCENTRATION
The initial concentration of metal Zinc provides an important driving force to outweigh all mass
transfer resistance of metal between the aqueous and solid phases (Wasewar, 2010). Removal of
Zinc for various initial concentrations (10 to 100 mg/L) by SIP waste (1g/L) at 26 min contact
time and at pH 7 has been depicted in the Fig.4.6. The percentage zinc adsorbed decreased
62.65% to 39.79% with increase in initial concentration from 10mg/L to 100mg/L whereas the
51
uptake increased from 6.26 - 39.79 mg/g. The saturated specific sites at higher initial metal
concentration may be responsible for decreasing percentage removal at increasing initial metal
concentration. It reflects that the resistance to mass transfer reduces therefore the removal
decreases at higher metal concentration. Similar results were reported by other researchers
(Yeddou Mezenner and Bensmaili, 2009; Can and Yildiz 2006).
Figure 4.6: Effect of Initial metal concentration on the rate of adsorption.
4.2.1.1.5 E FFECT OF T EMPERATURE
The effect of temperature on the removal of zinc ions by HCl treated adsorbent was studied in
the range 25-40◦C using 1g/L adsorbent, 30mg/L initial Zinc concentration, and at pH 7. The
percentage metal removal decreased from 65.5% to 60.2% with increase in temperature from 2540◦C (fig.4.7). These results indicate that low temperatures are in favour for removal of Zinc
ions onto SIP waste. This may be due to a tendency for the Zinc ions to escape from the solid
phase to the bulk phase with an increase in temperature of the solution. This effect shows that
adsorption mechanism related with removal of Zinc onto SIP waste is physical in nature in this
situation, in which adsorption take place from the electrostatic interaction, which is in general
related with low adsorption heat (Kula et al., 2008). This implies that the adsorption process was
exothermic in nature. Similar observation was also reported by (Jiang et al., 2009; Sari et al.,
2007).
52
Figure 4.7: Effect of temperature on percentage removal of zinc by SIP waste.
4.2.1.2 A DSORPTION ISOTHERMS
The equilibrium data for the adsorption are commonly known as adsorption isotherms. It is
essential to know them so as to compare the effectiveness of different adsorbent materials under
different operational conditions and also to design and optimize an adsorption system. Heavy
metal adsorption is usually modeled by the classical adsorption isotherms. In this study, four
isotherms models were used, Langmuir, Freundlich Dubinin-Radushkviech, Temkin isotherms
using Eqs (9),(12),(14),and(16) respectively. The values of various constants of the four models
were calculated and were represented in the Table 4.3.
Langmuir, Freundlich Dubinin-Radushkviech, and Temkin adsorption isotherms for zinc
from queous solution on SIP waste is presented in Figs 4.8-4.11 respectively. It indicates that the
experimental data fitted well to all the isotherm models expect D-R model. By comparing the
correlation coefficients, it was observed that Langmuir isotherm gives a good model for the
adsorption system, which is based on monolayer sorption on to the surface restraining finite
number of identical sorption sites. The maximum adsorption capacity of zinc from Langmuir
isotherm was found to be 64.10mg/g and all the RL values are for 10-100mg/L are 0.92-0.54
which were within the favorable range (0<RL<1). The free energy estimated from D-R model
indicates E value as 0.61(KJ/mol) which was less than 8 KJ/mol. It suggests that adsorption
process is physical in nature
.
53
Figure 4.8: Langmuir adsorption isotherm
Figure 4.10: D-R isotherm model for zinc
for zinc adsorption
adsorption
Figure 4.9: Frendluich adsorption isotherm
Figure 4.11: Temkin isotherm model for
for zinc adsorption
zinc adsorption
TABLE 4.3: Isotherm constants of zinc adsorption
Isotherms
Langmuir
qm (mg/g)
KL(L/mg)
R2
Freundlich
KF(mg/Kg)
N
R2
Temkin
A
B
R2
D-R
Values
64.10
0.029
0.9922
2.92
1.493
0.9811
1.292
194.049
0.9792
54
β(mol2kJ2)
qm (mg/g)
R2
4.5008
54.221
0.700
4.2.1.3 A DSORPTION KINETICS
The kinetics of adsorption was studied for a contact time ranging 1-32 min. The experimental
data was fitted to the pseudo first order and pseudo second order kinetic model (fig 4.12 & fig
4.13). The reported R2 value indicates that the experimental results shows better fit to pseudosecond order model. Hence, the zinc adsorption onto SIP waste seems to be more pseudo-second
order.
Similar
observation
was
also
reported
by
Azouaou
et.
al.,
(2010).
Figure 4.12: Pseudo first order kinetics plot
Figure 4.13: Pseudo second order kinetics
for Zinc Adsorption
plot for zinc adsorption
4.2.1.4 A DSORPTION MECHANISM
The contact time variation experiments were used to study the rate-determining step in the
adsorption process. Since the particles were agitated at a speed of 180 rpm, it can be assumed
that the rate is not controlled by mass transfer from the bulk liquid to the external surface of the
particle. As a result, the rate determining step might be either film or intra-particle diffusion. As
both act in series, the slower one of the two would be the rate-determining step.
TABLE 4.4: Intraparticle rate parameters, external mass transfer and diffusion coefficients
Diffusion Model
Intra Particle Diffusion
Kid (mg/g min0.5)
R2
Film Diffusion
Values
1.472
0.966
55
D1(m2/s)
2.988×10-7
2
R
0.9662
D2(m2/s)
2.909×10-9
2
R
0.751
The kid values were obtained from the slope of the plot between qt verses t1/2 and the
results are shown in Table 4.4. From „R2‟ values, it can be concluded that the process is pore
diffusion controlled. The initial curved portion relates to the film diffusion (D1) and the later
linear portion represents the diffusion (D2) within the adsorbent. Assuming adsorbent particle to
be having spherical geometry, the relationship between weight uptake and time using Ficks law
is shown equation (23, 24). Using these equations, „D1‟, „D2‟ values were calculated. Table 4.4
shows the „D1‟, and „D2‟ values along with the „R2‟ values. Among the film and pore diffusion
film diffusion is considered to be the rate controlling in the adsorption mechanism because of its
lower diffusion coefficients.
4.2.1.5 T HERMODYNAMIC STUDY OF ADSORPTION PROCESS
The temperature dependence during the adsorption process provides the information about
enthalpy and entropy changes associated with the process (Ijagbemi, et al., 2009).The
thermodynamic parameters such as Gibbs free energy (∆G◦), enthalpy change (∆H◦), and entropy
(∆S◦) estimated explains the feasibility and the nature of adsorption process. The results of the
thermodynamic calculations are shown in Table 4.5.
The negative value of ∆G◦ indicates that the process is thermodynamically spontaneous. The
negative value of ∆H◦ for the removal of zinc confirms that the adsorption process was
exothermic in nature. The negative value of ∆S◦ and zinc in bulk phase was in much more
chaotic distribution compared to the relatively ordered state of solid phase respectively. Similar
results were observed by other researchers Azouaou et.al., (2010). The lnk vs 1/T plot is give in
the Fig 4.14
56
Figure 4.14: The Vant Hoff‟s plot of ln K vs. 1/T
TABLE 4.5: Thermodynamic parameters of zinc adsorption.
T(K)
298
303
308
313
ln K
∆G(KJ mol-1)
3.21
3.40
3.55
3.68
-7.97
-8.56
-9.10
-9.59
∆H(KJ mol-1)
∆S(J mol-1 K1)
-12.09
-35.09
4.2.2 NICKEL
4.2.2.1 E FFECT OF PARAMETERS
4.2.2.1.1 E FFECT OF CONTACT TIME
The effect of contact time on nickel adsorption process was determined by conducting adsorption
experiments at different contact time between the adsorbate and adsorbent in the range of 1–34
min. The concentration of metal ions was 30mg/L, pH was kept as 6.0, and temperature 30°C,
while the amount of SIP waste added was 1g/L. From Fig 4.15, the plot depicts that the rate of
percent removal of nickel was higher at the beginning. This may be due to the larger surface area
of the adsorbent being available at beginning for the adsorption of nickel ions. Equilibrium
adsorption was reached within a short period of around 28 min indicating that the adsorption
sites are well exposed (Orumwense , 1996). It is clear for the results that the adsorption of nickel
was dependent on contact time. Based on these results, all the batch experiments were conducted
with a contact time of 1-30 min.
57
Figure 4.15: Effect of contact time on adsorption of Nickel ions
4.2.2.1.2 E FFECT OF A DSORBENT DOSE :
The effect of SIP waste on Nickel adsorption from aqueous solution was determined by carrying
out experiments at initial concentration 20mg/L, temperature 30◦C, and pH 6. The results of
adsorbent dose on the percentage removal of Nickel metal on SIP waste is reflected in Fig 4.16.
Initially the metal uptake increased with adsorbent dose 0.1g/L to 2/L and reached equilibrium at
1g/L. It is due to increased adsorbent surface area and availability of more adsorption sites (Cay
et al., 2004). However at 2g/L adsorbent dose the metal ions adsorbed per unit weight of
adsorbent decreased which is due to the fact that at higher adsorbent dose the solution ion
concentration drops to a lower value of q indicating the adsorption sites to remain unsaturated
(Amarasinghi and Williams 2007).Based on these results 1g/L was taken as optimum adsorbent
dose for the rest experiments.
Figure 4.16: Effect of Adsorbent Dose on Zn adsorption.
58
4.2.2.1.3 E FFECT OF P H
The effect of pH is an important parameter in adsorption process, particularly for treatment of
wastewater since their initial pH various widely. It is having significant impact on the uptake of
metals, as it determines the surface charge of the adsorbent, the degree of ionization and
specification of the adsorbent ( El-Ashtoukhy et al., 2008). Nickel ions exist in different forms in
aqueous solution and the stability of these forms is dependent of the pH of system. The effect of
pH on adsorption of nickel is shown in Fig.4.17.
The effect of pH on adsorption of nickel was studied at 30◦C, initial metal concentration
30mg/L, adsorbent dose 1g/L by varying the pH of metal solution from 2-6.5. The percentage
adsorption increases with increase in pH. The minimum adsorption was observed at low pH may
be due the fact that the presence of higher concentration and higher mobility of H+ ions favoured
adsorption compared to M (II) on the other hand in the acidic medium due to high solubility and
ionization of metal ions. The surface of the adsorbent becomes more positively charged at high
H+ concentration such that the attraction between adsorbents and metal cations is reduced. In
reverse with increase in pH the negatively charged surface area becomes more thus facilitating
grater metal removal. The maximum adsorption was observed within the pH range 4 to 6.5
which might be due to partial hydrolysis of metal ions (Onundi et al., 2010).. Further increase in
pH i.e., above 6.5 of the solution causes precipitation of Ni ion on the surface of the adsorbent by
nucleation (Agrawal et al, 2004, Inbaraj and Sulochana, 2006).From these results it was clear
that the maximum metal uptake was at 6.5 pH i.e, 44.38% based on this pH 6.5 was taken has
optimum pH for rest of the experiments.
Figure 4.17: Effect of pH on adsorption of Nickel ions
59
4.2.2.1.4 E FFECT OF INITIAL METAL CONCENTRATION
The effect of initial metal concentration on nickel removal was evaluate by conducting
experiments by varying initial concentrations from 10 -100 mg/L by keeping adsorbent dose at (1
g/L), pH (6.5), temperature (30°C) and contact time 28 min constant.
Figure 4.18: Effect of Initial metal concentration on adsorption of Nickel ions
Fig 4.18 depicts the effect of initial metal concentration on percentage removal of nickel. The
percentage nickel adsorbed decreased 58.70% to 14.76% with increase in initial concentration
from 10mg/L to 100mg/L. The saturated specific sites at higher initial metal concentration are
responsible for decreasing metal uptake at increasing initial metal concentration. It reflects that
the resistance to mass transfer reduces therefore the uptake decreases at higher metal
concentration. Similar results were reported by other researchers (Yeddou Mezenner and
Bensmaili, 2009; Can and Yildiz 2006).
4.2.2.1.5 E FFECT OF T EMPERATURE
The temperature dependence of the adsorption process is related with several thermodynamic
parameters.
The effect of temperature on the removal of nickel ions by HCl treated adsorbent was
studied in the range 25-40◦C using 1g/L adsorbent, 30mg/L initial Nickel concentration, and at
pH 6.5. The percentage metal removal decreased from 57.4% to 50.7% with increase in
temperature from 25-40◦C (fig.4.19). These results indicate that low temperatures are in favour
for removal of Nickel ions onto SIP waste. This may be due to a tendency for the Nickel ions to
60
escape from the solid phase to the bulk phase with an increase in temperature of the solution.
This effect shows that adsorption mechanism related with removal of nickel onto SIP waste is
physical in nature in this situation, in which adsorption take place from the electrostatic
interaction, which is in general related with low adsorption heat (Kula, 2008). This implies that
the adsorption process was exothermic in nature. Similar observation was also reported by (Jiang
et al., 2009; Sari et al., 2007).
Figure 4.19: Effect of Temperatureon adsorption of Nickel ions
4.2.2.2 A DSORPTION ISOTHERMS
The experimental data obtained was fitted to isotherm models such as, Langmuir, Freundlich
Dubinin-Radushkviech, Temkin isotherms using Eqs (9), (12), (14), and (16) respectively. The
values of various constants of the four models were calculated and were represented in the Table
4.6.
Adsorption isotherms for nickel adsorption from aqueous solution on SIP waste is presented in
Fig 4.20- 4.23. By comparing the correlation coefficients, it was observed that Langmuir
isotherm gives a good model for the adsorption system, which is based on monolayer sorption on
to the surface restraining finite number of identical sorption sites. The maximum adsorption
capacity of nickel from Langmuir isotherm was found to be 14.08 mg/g and the RL values for 10100mg/L are 0.2-0.02 which were within the favorable range (0<RL<1). The R2 value for the
Freundlich isotherm was very less which shows that the adsorption of nickel on SIP waste was
not a multilayer adsorption. The free energy estimated from D-R model indicates E value as
0.4177(KJ/mol) which was less than 8 KJ/mol. It suggests that adsorption process is physical in
nature.
61
Figure 4.20: Langmuir isotherm model for
Figure 4.22: D-R isotherm model for Nickel
Nickel adssorption
adssorption
Figure 4.21: Freundlich isotherm model for
Figure 4.23: Temkin isotherm model for
Nickel adssorption
Nickel adssorption
TABLE 4.6: Isotherm constants of nickel adsorption on SIP waste.
Isotherms
Langmuir
qm (mg/g)
KL(L/mg)
R2
Freundlich
KF(mg/Kg)
N
R2
Temkin
A
B
R2
D-R
β(mol2kJ2)
Values
14.08
0.379
0.9745
5.92
4.76
0.564
0.989
1253.92
0.526
2.86
62
qm (mg/g)
R2
13.68
0.900
4.2.2.3 A DSORPTION KINETICS :
The kinetics of adsorption was studied for a contact time ranging 1-36 min. The experimental
data was fitted to the pseudo first order and pseudo second order kinetic model (fig 4.24 & fig
4.25). The reported R2 value indicates that the experimental results shows better fit to pseudosecond order model. Hence, the nickel adsorption onto SIP waste seems to be more pseudosecond order. Similar observation was also reported by Azouaou et.al., (2010).
Figure 4.24: Pseudo first order kinetics plot for nickel adsorption.
Figure 4.25: Pseudo second order kinetics plot for nickel adsorption.
4.2.2.4 A DSORPTION MECHANISM
The contact time variation experiments were used to study the rate-determining step in the
adsorption process. Mass transfer from the bulk liquid to the external surface of the particle was
neglected as the particles were agitated at a speed of 180 rpm As a result, the rate determining
63
step might be either film or intra-particle diffusion. As both act in series, the slower one of the
two would be the rate-determining step.
TABLE4.7: Intraparticle rate parameters, external mass transfer and diffusion
coefficients
Diffusion Model
Values
Intra Particle Diffusion
Kid (mg/g min0.5)
2.49
2
R
0.99
Film Diffusion
D1(m2/s)
1.91×10-7
R2
0.994
2
D2(m /s)
2.909×10-9
R2
0.898
The kid values were obtained from the slope of the plot between qt verses t1/2 and the
results are shown in Table 4.7. From „R2‟ values, it can be concluded that the process is pore
diffusion controlled. The initial curved portion relates to the film diffusion (D1) and the later
linear portion represents the diffusion (D2) within the adsorbent. Assuming adsorbent particle to
be having spherical geometry, the relationship between weight uptake and time using Ficks law
is shown equation (23, 24). Using these equations, „D1‟, „D2‟ values were calculated. Table 4.7
shows the „D1‟, and „D2‟ values along with the „R2‟ values. Among the film and pore diffusion
film diffusion is considered to be the rate controlling in the adsorption mechanism because of its
lower diffusion coefficients.
4.2.2.5 T HERMODYNAMIC STUDY OF ADSORPTION PROCESS
The temperature dependence during the adsorption process provides the information about
enthalpy and entropy changes associated with the process (Ijagbemi et al., 2009). The
thermodynamic parameters such as Gibbs free energy (∆G◦), enthalpy change (∆H◦), and entropy
(∆S◦) estimated explains the feasibility and the nature of adsorption process. These parameters
were from the slope and intercept of the plot lnk vs. 1/T (Fig 4.26).The results of the
thermodynamic parameters calculated using Eq (26) was shown in Table 4.8.
The negative value of ∆G◦ indicates that the process is thermodynamically spontaneous.
The negative value of ∆H◦ for the removal of nickel confirms that the adsorption process was
64
exothermic in nature. The negative value of ∆S◦ and nickel in bulk phase was in much more
chaotic distribution compared to the relatively ordered state of solid phase respectively. Similar
results were observed by other researchers Azouaou et.al., (2010).
TABLE 4.8: Thermodynamic parameters of nickel adsorption.
T(K)
ln K
∆G(KJ mol-1)
∆H(KJ mol-1)
∆S(J mol-1 K1)
298
303
308
313
0.298
0.202
0.150
0.028
-0.738
-0.510
-0.384
-0.072
-13.36
-42.35
Figure 4.26: Plot of lnk vs. 1/T
4.2.3 COPPER
4.2.3.1 E FFECT OF PARAMETERS
4.2.3.1.1 E FFECT OF C ONTACT TIME
The removal of copper on SIP waste from aqueous solution was studied as function of contact
time in the range of 2-34 min at 20mg/L initial metal concentration, 5 pH, 1g/L SIP waste, and
30ºC temperature. The effect of contact time on removal of copper is shown in the Fig 4.27.
From the figure it was observed that the rate of zinc removal was higher at the beginning until
30min and, thereafter, the adsorption rate become practically constant. The difference in the
degree of adsorption may be due to the fact that in the beginning all the sites on the surface of the
adsorbent were vacant and the solute concentration gradient was relatively high (Yeddou
65
Mezenner and Bensmaili, 2009). As a result, the extent of copper removal decreased with
increase in contact time, which is dependent on the number of vacant sites on the surface of SIP
waste. Based on these results 30min was considered as the optimum time for the rest of the
experiments.
Figure 4.27: Effect of contact time on copper removal.
4.2.3.1.2 E FFECT OF P H
The effect of pH on removal of copper using SIP waste was studied by conducting a set of
experiments by adjusting the pH from 2-6. The results obtained were shown in the Fig 4.28. As
the pH varied from 2-6 the adsorption rate of copper was increased from 5.65-32.75%. The
minimum adsorption was observed at low pH may be due the fact that the presence of higher
concentration and higher mobility of H+ ions favoured adsorption compared to M (II) on the
other hand in the acidic medium due to high solubility and ionization of metal ions. The surface
of the adsorbent becomes more positively charged at high H+ concentration such that the
attraction between adsorbents and metal cations is reduced. Further increase in pH i.e., above 7
of the solution causes precipitation of zinc ions on the surface of the adsorbent by nucleation
(Agrawal et al, 2004; Inbaraj and Sulochana, 2006). According to these results pH 6 was taken as
optimal value for the rest of the experiments.
66
Figure 4.28: Effect of pH on copper removal.
4.2.3.1.3 E FFECT OF INITIAL METAL CONCENTRATION
The effect of initial copper concentration on the copper adsorption rate was studied in the rage
(10-100mg/L) at pH 6, temperature 30ºC, and 30min contact time. The results presented in the
Fig 4.29. From the figure it was observed that the percentage of removal decreased with
increasing in initial copper concentration. The poorer uptake at higher metal concentration was
resulted due to the increased ratio of initial number of moles of copper to the vacant sites
available. For a given adsorbent dose the total number of adsorbent sites available was fixed thus
adsorbing almost the equal amount of adsorbate, which resulting in a decrease in the removal of
adsorbate, consequent to an increase in initial copper concentration. Therefore it was evident
from the results that copper adsorption was dependent on the initial metal concentration. Similar
results were also reported by other researchers (Nasir et al., 2007; Dahiya et al., 2008).
Figure 4.29: Effect of the initial metal concentration on copper adsorption.
67
4.2.3.1.4 E FFECT OF T EMPERATURE
The effect of temperature on the removal of copper ions by HCl treated adsorbent was studied in
the range 25-40◦C using 1g/L adsorbent, 20mg/L initial copper concentration, and at pH 6. The
percentage metal removal decreased from 37.15% to 33.8% with increase in temperature from
25-40◦C (fig.4.30). The decrease in adsorption percentage with increase in temperature indicated
that low temperature was in favour of copper removal onto SIP waste. This may be due to a
tendency for the copper ions to escape from the solid phase to the bulk phase with an increase in
temperature of the solution. This implies that the adsorption process was exothermic in nature.
Similar observation was also reported by (jiang et al 2009, Sari et al, 2007).
Figure 4.30: Effect of temperature on copper removal by SIP waste
4.2.3.2 A DSORPTION ISOTHERMS
The experimental data obtained from copper adsorption experiments were fitted to different
isotherm models such as, Langmuir, Freundlich Dubinin-Radushkviech, Temkin isotherms using
Eqs (9), (12), (14), and (16) respectively. The isotherm models were presented in the Figs 4.314.34 respectively. The values of various constants obtained from these plots for the four models
were calculated and represented in the Table 4.9.
TABLE 4.9: Isotherm constants of copper adsorption.
Isotherms
Langmuir
qm (mg/g)
Values
11.79
68
KL(L/mg)
R2
Freundlich
KF(mg/Kg)
N
R2
Temkin
A
B
R2
D-R
β(mol2kJ2)
qm (mg/g)
R2
Figure 4.31: Langmuir isotherm model for
copper removal.
0.091
0.987
2.49
2.94
0.913
1.00
1063.3
0.938
16.13
50.39
0.709
Figure 4.33: D-R isotherm model for
copper adsorption.
Figure 4.34: Temkin isotherm molel for
copper adsorption.
Figure 4.32: Freundlich isotherm model for
copper adsorption.
69
By comparing the R2 it was observed that the Langmuir isotherm was good fit among the four
isotherms. Thus from these results it was apparent that the adsorption of copper onto SIP waste
was monolayer sorption. The maximum adsorption capacity of copper from Langmuir isotherm
was found to be 11.79mg/g and all the RL values are for 10-100mg/L are 0.52-0.09 which were
within the favourable range (0<RL<1). The free energy estimated from D-R model indicates E
value as 0.17(KJ/mol) which was less than 8 KJ/mol. It suggests that adsorption process is
physical in nature.
4.2.3.3 A DSORPTION K INETICS
The kinetics of adsorption was studied for a contact time ranging 1-30 min. The experimental
data was fitted to the pseudo first order and pseudo second order kinetic model (fig 4.35 & fig
4.36).
Figure 4.35: Pseudo first order kinetics plot for copper Adsorption
70
Figure 4.36: Pseudo second order kinetics plot for copper adsorption
4.2.3.4 A DSORPTION MECHANISM
The kid values were obtained from the slope of the plot between qt verses t1/2 and the
results are shown in Table 4.10. From „R2‟ values, it can be concluded that the process is pore
diffusion controlled. The initial curved portion relates to the film diffusion (D1) and the later
linear portion represents the diffusion (D2) within the adsorbent. Assuming adsorbent particle to
be having spherical geometry, the relationship between weight uptake and time using Ficks law
is shown by equation (23, 24). Using these equations, „D1‟, „D2‟ values were calculated. Table
4.10 shows the „D1‟, and „D2‟ values along with the „R2‟ values. Among the film and pore
diffusion film diffusion is considered to be the rate controlling in the adsorption mechanism
because of its lower diffusion coefficients.
TABLE 4.10: Intraparticle rate parameters, external mass transfer and diffusion
coefficients
Diffusion Model
Intra Particle Diffusion
Kid (mg/g min0.5)
R2
Film Diffusion
D1(m2/s)
R2
D2(m2/s)
R2
Values
0.443
0.979
2.77×10-07
0.978
6.67×10-06
0.782
4.2.3.5 T HERMODYNAMIC STUDY OF ADSORPTION PROCESS
The temperature dependence during the adsorption process provides the information about
enthalpy and entropy changes associated with the process (Ijagbemi et al., 2009). The
thermodynamic parameters such as Gibbs free energy (∆G◦), enthalpy change (∆H◦), and entropy
(∆S◦) estimated explain the feasibility and the nature of adsorption process. These parameters
were from the slope and intercept of the plot lnk vs. 1/T (Fig 4.37).The results of the
thermodynamic parameters calculated using Eq (26) was shown in Table 4.11
71
The negative value of ∆G◦ indicates that the process is thermodynamically spontaneous.
The negative value of ∆H◦ for the removal of nickel confirms that the adsorption process was
exothermic in nature. The negative value of ∆S◦ and nickel in bulk phase was in much more
chaotic distribution compared to the relatively ordered state of solid phase respectively. Similar
results were observed by other researchers Azouaou et.al., (2010).
TABLE 4.11: Thermodynamic parameters of nickel adsorption.
T(K)
ln K
∆G(KJ mol-1)
∆H(KJ mol-1)
∆S(J mol-1 K1)
298
303
308
313
-0.52
-0.57
-0.61
-0.67
-1.30
-1.46
-1.57
-1.74
-7.38
-29.16
z
Figure 4.37: Plot lnk vs. 1/T
72
TABLE 4.12: Comparison of adsorption capacities with other adsorbents at standard conditions.
Metal
Zn
Ni
Adsorbent
% Adsorption
-1
Work done by
Modified Groundnut shells
9.57mgg
Shukla and Pai (2005b)
Cocunut shell
99.74%,
Olayinka et al., (2007)
waste tea
90.74%
Olayinka et al., (2007)
-1
SIP waste
64.10mgg ,65.5%
present study
sludge–ash
99%
Chih-Huang, (2002)
palm kernel shell
0.130 mgg-1
Onundi et al., (2010)
hydrolyzed poly-methyl methacrylate
59%
Atul et al., ( 2011)
SIP waste
14.08 mgg-1 ,44.38%
polyacrylamide
-1
33mgg .
-1
present study
Zhao et al., (2010)
expanded perlite (EP
1.95 mgg .
Ghassabzadeh et al., (2010)
sawdust
1.79 mgg-1.
Yu et al.,(2000)
SIP waste
11.79mgg-1
present study
Cu
4.2.4 CO- ADSORPTION OF ZINC AND NICKEL
Generally Industrial wastewater contains more than one type of metal ions. Therefore, the effect
of co-adsorption of multiple metal ions on adsorption of individual ions was estimated. The
percentage removal of zinc and nickel from a bimetal solution containing both zinc and nickel at
different metal concentrations and temperatures were investigated.
4.2.4.1 E FFECT OF PARAMETERS
4.2.4.1.1 E FFECT OF INITIAL METAL CONCENTRATION
The effect of initial metal concentration on adsorption was investigated by using a wide range of
initial metal ion concentrations (10-100mg/L) of the binary solution (Zn, Ni) at pH 6.5,1g/L
adsorbent, 30ºC temperature, at 28 min contact time for Zn and 30 min for Ni has been depicted
in the Fig.4.38. The percentage removal of zinc and nickel ions decreases from 59.06% to
36.43% and 48.02% to 12.68% respectively with increase in metal concentration from 10100mg/L. The saturated specific sites at higher initial metal concentration are responsible for
decreasing metal uptake at increasing initial metal concentration. It reflects that the resistance to
mass transfer reduces therefore the uptake decreases at higher metal concentration. Similar
results were reported by other researchers (Yeddou Mezenner and Bensmaili, 2009; Can and
73
Yildiz 2006).The percentage removal of zinc is more compared to nickel has in the case of noncompetitive adsorption conditions. The difference in adsorption behavior of zinc compared to
nickel may be due to the different affinity of metal ions for the different donor atoms (i.e.
oxygen, sulphur and nitrogen) in the SIP waste structure. This behavior may also due to the
complexing groups present on the adsorbent resulting in a relatively high adsorption of zinc ions.
Similar results were reported by other researchers (SolmazKarabulut et al., 2000).
Figure 4.38: Effect of initial metal concentration on adsorption of Zn, Ni ions onto SIP waste.
4.2.4.1.2 E FFECT OF TEMPERATURE
Effect of temperature on co- adsorption of Zn and Ni onto SIP waste was examined within a
range of 25-40ºC at pH 6.5, 1g/L adsorbent dose, 20mg/l of initial metal concentration. The
percentage zinc removal decreased from 62.85% to 57.29% and nickel removal decreased from
48.02-42.03% with increase in temperature from 25-40◦C (fig.4.39).
Figure 4.39: Effect of temperature on Co-adsorption of Zn and Ni ions onto SIP waste.
74
The decrease in adsorption percentage with increase in temperature indicated that low
temperature was in favor of Zn, Ni removal onto SIP waste. This may be due to a tendency for
the copper ions to escape from the solid phase to the bulk phase with an increase in temperature
of the solution. Thus it implies that the adsorption process was exothermic in nature. This has
shown similar trend as in the single metal removal.
4.2.4.2 E FFECT OF CO - ADSORPTION
The percentage removal of zinc and nickel from a bimetal solution containing both
zinc and nickel at the solution pH of 6.5, the liquid temperature of 25ºC was investigated. The
percentage removal of zinc and nickel for both individual ion and bimetal solution has been
depicted in Fig 4.40. The figure shows that the removal of zinc was higher than that of nickel for
both individual ion adsorption and co-adsorption with the bimetal solution. There was no
significant effect on the adsorption zinc due to the presence of nickel. In contrast, the removal of
nickel decreased from 57.40% for the single-ion nickel solution to 48% in the presence of zinc
co-adsorption. In the mass transfer standpoint, the diffusivity of zinc (7.016×10−10m2 s−1) was
about 15% higher than that of nickel (6.132×10−10m2 s−1) (Anderko, and Lenka, 1998).
Therefore, the mass transfer rate of zinc from the bulk liquid to the surface of the adsorbent was
higher than that of nickel; hence, the adsorption of zinc was better. Similar results were reported
by other researchers (Doan et al., 2008).
75
Figure 4.40: Effect of co-adsorption on the adsorption of individual metal ions on SIP waste.
76
5 RESULTS AND DISCUSSION- COLUMN
ADSORPTION
5.1 EFFECT OF PARAMETERS
5.1.1 EFFECT OF BED HEIGHT
The effect of bed height was investigated by conducting experiments at constant feed
concentration of 20mgL−1, flow rate 20mLmin−1, temperature 25ºC, and pH 6.5 based on the
batch adsorption experiments with bed height ranging from 5 to 15cm. Figs 5.1& 5.2 shows the
effect of bed height on adsorption of zinc and nickel. The different operating parameters for zinc
and nickel are given in Tables 5.1 and 5.2 respectively. From the results it was observed that
both breakthrough time and exhaustion time increased with increase in bed height, as more
binding sites are available for sorption, it also resulted in a broadened mass transfer zone. As the
bed height increases, the length of the bed through which the solution containing metal ion
passes also increases. The percentage adsorption increased from 40% – 62.05% for zinc and
31.23%- 56.43% for nickel with increase in bed height form 5 to 15cm for both the metals and
this is due to the increase in SIP waste dosage in larger beds which provide increased surface
area and more binding sites for adsorption (Fu and Viraraghavan 2003).
Figure 5.1: Break through curve for zinc at different bed heights.
77
Figure 5.2: Break through curve for nickel at different bed heights
5.1.2 EFFECT OF FLOW RATE
The influence of flow rate on the adsorption of Ni and Zn by SIP waste was investigated by
keeping initial metal ion concentration (20mgL−1), temperature (25ºC) and bed height (5cm), and
pH 6.5 constant and varying the flow rate from 10 to 20mLmin−1. At low flow rate the column
performance was well. Initially the adsorption was very rapid at lower flow rates may be
associated with the availability of adsorption sites to capture metal ions around or inside the
adsorbent. In the next stage of the process due to the gradual occupancy of these sites, the uptake
becomes less effective. From the Figs. 5.3 and 5.4, an earlier breakthrough and exhaustion time
was observed which resulted in steeper breakthrough curves, when the flow rate was increased
from 10 to 20mLmin−1. The flow rate also strongly influenced the metal uptake capacity. When
flow rate increased from 10 to 20mLmin−1 the % removal decreases from 60.75 to 40.92% for
zinc and 56.17 to 31.23% for nickel. Results are shown in Tables 5.1 and 5.2. The credible
reason behind this is that when the residence time of the metal in the column is not long enough
for adsorption equilibrium to be reached at that flow rate, the metal solution leaves the column
before equilibrium occurs. Consequently, the contact time of metal ions with the adsorbent is
very short at higher flow rate, causing a reduction in removal efficiency (Ghorai and Pant, 2005).
78
Figure 5.3: Break through curves for zinc at different flow rate.
Figure 5.4: Break through curves for nickel at different flow rate.
TABLE 5.1: Zinc adsorption data on SIP waste in a fixed bed column at different operating
conditions.
Z (cm)
F(ml.min-1)
Q exp(mg.g-1)
tb(min)
te(min)
∆t=(te-tb)
Zm=Z(1-(tb-te))
% Removal
5
10
15
20
20
20
26.13
26.52
25.36
28
68
140
209
432
650
181
364
510
910
3650
7665
40.92
60.78
62.05
79
5
5
15
10
30.82
36.26
43
68
320
523
277
455
1390
2280
48.94
60.75
TABLE 5.2: Nickel adsorption data on SIP waste in a fixed bed column at different operating
conditions.
Z (cm)
5
10
15
5
5
F(ml.min-1)
Q exp(mg.g-1)
tb(min)
te(min)
∆t=(te-tb)
Zm=Z(1-(tb-te))
% Removal
20
20
20
15
10
22.84
21.87
22.36
25.76
34.75
38
69
130
61
50
149
274
530
193
250
111
205
400
132
200
560
2060
6015
665
1005
31.23
51.49
56.43
50.12
56.17
5.2 REGENERATION STUDIES
The reusability of adsorbent is related to the application potential of adsorption technology.
Thus, regeneration of the adsorbent material is of critical importance in the economic
development. Regeneration is the removal of metal adsorbed on the SIP waste using an eluting
agent. This must produce small volume of metal concentrates suitable for metal-recovery
process, without damaging the capacity of the adsorbent, making it reusable in several
adsorptions and desorption cycles. Regeneration should also guarantee that eluted solution is not
posing any disposal problem waste in terms of high acidity. In the present study, elution of zinc
and nickel were carried out using HCl as desorbing agent at constant flow rate of 20mLmin −1,
and bed height of 5cm preloaded with 20mgL−1 of zinc and nickel as feed concentration shown
in the Fig 5.5and 5.6. After the recovery of metal ion, the regenerated SIP waste was thoroughly
washed with distilled water and again loaded with zinc and nickel solution of concentration of
20mgL−1. The column regeneration studies were carried out for adsorption–desorption cycles for
both zinc and nickel. The same operating conditions were employed for all the adsorption–
desorption cycles. The actual bed length remained constant during the regeneration cycles. A
decreased breakthrough time was observed as the regeneration cycles progressed. This behaviour
is mainly due to stable deterioration of SIP waste because of continuous usage. The regeneration
efficiency was found to be 62.51% and 82.29% for zinc and nickel respectively.
80
Figure 5.5: Elution curves for zinc columns using 0.1 N HCl.
Figure 5.6: Elution curves for nickel columns using 0.1 N HCl
5.3 MODELING OF BREAKTHROUGH CURVE
5.3.1 THOMAS MODEL
Thomas model was used to predict the breakthrough curves under varying experimental
conditions. The values of the thomas model parameters were given in the Table 5.3. From the
results it was observed that Qo values calculated from the Thomas model is close to the Q, exp
81
values obtained experimentally for both zinc and nickel. Therefore model gave good agreement
between experimental and calculated breakthrough curves.
TABLE 5.3: Thomas Model constants for zinc and nickel
Metal
Zn
Ni
Z (cm)
F(ml.min-1)
Q exp(mg.g-1)
5
10
15
5
5
5
10
15
5
5
20
20
20
15
10
20
20
20
15
10
26.13
26.52
25.36
30.82
36.26
22.84
21.87
22.36
25.76
34.75
Parameters of Thomas Model
KTh(L.min-1.mg-1)
Q0(mg.g-1)
R2
0.000685
0.000965
0.002015
0.00157
0.00082
0.000915
0.00178
0.00312
0.00233
0.00192
30.01
28.19
25.94
29.28
35.15
24.27
19.22
22.15
27.59
35.33
0.9777
0.9615
0.9238
0.9067
0.9517
0.9893
0.9762
0.98
0.9768
0.9913
82
6 CONCLUSION
The present study on adsorption of Zinc, Nickel and Copper from aqueous solutions using SIP
waste suggested the following conclusions:

SIP Waste showed very minor changes in surface properties after HCl treatment.

Influence of process parameters such as pH, adsorbent dosage, temperature, contact time,
initial metal concentration was moderate such that they can affect the removal
efficiencies of the heavy metals.

The adsorption process was dependent on metal solution pH. The optimum pH for Zn, Cu
and Ni were 7, 6 and 6.5 respectively.

Effect of temperature showed that adsorption decreased with increase in temperature and
the optimum was found to be 25◦C.

The optimum amount of adsorbent dosage was found to be 1 mg/L.

Initial metal concentration showed negative impact on the adsorption efficiency i.e at
lower levels the adsorption was higher.

The adsorption data was fitted to different adsorption isotherm model equation that
indicated Langmuir model to fit best for all three metals i.e. Zn, Ni, and Cu with R 2
values 0.992, 0.974, 0.987 respectively.

Kinetics studies of adsorptions for all three metals revealed that the adsorption process
follows a pseudo second order for all of them.

Among the film and pore diffusion models, film diffusion is considered to be the rate
controlling in the adsorption mechanism because of its lower diffusion coefficients
83

The thermodynamic parameters such as Gibbs free energy (∆G◦), enthalpy change (∆H◦),
and entropy (∆S◦) estimated explained that the adsorption of Zn, Ni, and Cu on SIP waste
is exothermic in nature.

Co-adsorption studies showed that the removal of zinc was higher than that of nickel for
both individual ion adsorption and co-adsorption. There was no significant effect on the
adsorption of zinc in presence of nickel.

Colum studies revealed that when bed height increased from 5cm to 15cm, the percentage
adsorption increased from 40% – 62.05% for zinc and 31.23%- 56.43% for nickel Also
when flow rate increased from 10 to 20mLmin−1 the % removal decreases from 60.75 to
40.92% for zinc and 56.17 to 31.23% for nickel.

The elution of zinc and nickel were carried out using 0.1N HCl as desorbing agent at
constant flow rate of 20mLmin−1, and bed height of 5cm preloaded with 20mgL−1 of zinc
and nickel as feed concentration. The regeneration efficiency was found to be 62.51%
and 82.29% for zinc and nickel respectively.

The Thomas model used to predict the breakthrough curves under varying experimental
conditions was found to be good fit.

The above findings clearly indicate that the SIP Waste has good potential for being
utilized as an adsorbent in the heavy metal removal process from waste waters.
84
7 BIBLIOGRAPHY
Abbas H.S., Mumtaz A.Z., Anaam A.S., 2009. Electrolytic removal of zinc using a flow-through
cell with amalgamated copper screen cathode. Eng. & Tech. J. 27 (2), 2009.
Adhoum, N., Monser, L., Bellakhal, N., Belgaied, J.E., 2004. Treatment of electroplating
wastewater containing Cu2+, Zn2+ and Cr(VI) by electrocoagulation. J. Haz. Mat.
B112, 207.
Agency for Toxic Compounds and Disease Registry (ATSDR), Toxicological Profile for Zinc,
Public Health Service, U.S. Department of Health and Human Services, Atlanta,
Georgia, 1993.
Agrawal, A., Sahu, K.K., and Padey, B.D., 2004. Removal of zinc from aqueous solution using
sea nodule residue. Colloids Surfaces. 237, 133-140.
Aguayo-Villarreal, I.A., Bonilla-Petriciolet, A., Hernández-Montoya, V., Montes-Morán, M.A.,
and Reynel-Avila, H E., 2011. Batch and column studies of Zn2+ removal from
aqueous solution using chicken feathers as sorbents. Chem. Eng. J. 167, 67–76.
Akbal, F., and Camcı, S., 2010.Comparison of Electrocoagulation and Chemical Coagulation for
Heavy Metal Removal. Chem Eng Technol. 33, 1655.
Akbal, F., and Camcı, S., 2011. Copper, chromium and nickel removal from metal plating
wastewater by electrocoagulation. Desalination. 269, 214-222.
Aksu, Z., and Gonen, F., 2004. Biosorption of phenol by immobilized activated sludge in a
continuous packed bed: prediction of breakthrough curves. Proc. Biochem. 39, 599613.
Al-Asheh, S., Duvnjak, Z., 1997. Sorption of cadmium and other heavy metals by pine bark.
Adv. Environ. Res. 1, 194.
Alvarez, M. T., Crespo, C., Mattiasson, B., 2007. Precipitation of Zn(II), Cu(II) and Pb(II) at
bench-scale using biogenic hydrogen sulfide from the utilization of volatile fatty
acids. Chemosphere 66, 1677.
85
Alyüz, B., Veli, S., 2009. Kinetics and equilibrium studies for the removal of nickel and zinc
from aqueous solutions by ion exchange resins. J. Hazard. Mater. 167, 482.
Amarasinghi, B.M.W.P.K., and Williams, A.R., 2007. Tea waste as a low cost adsorbent for the
removal of Cu and Pb from waste water. Chem. Eng. J. 132, 299-309.
Aminah, S., Babu, S., (2009). Biosorption of zinc (II) from aqueous solution by using dried
water hyacinth (Eichhornia crassipes). Eng D thesis, Universiti Malaysia Pahang.
Anderko, A. and Lenka, M.M., 1998. Modeling self-diffusion in multi-component aqueous
electrolyte systems in wide concentration ranges. Ind Eng Chem Res. 37, 2878–2888.
Argun, M.E., 2008. Use of clinoptilolite for the removal of nickel ions from water: kinetics and
thermodynamics. J. Hazard. Mater. 150, 587-595.
Argun, M.E., Dursun, S., Ozdemir, C., and Karatas, M., 2007. Heavy metal adsorption by
modified oak sawdust: Thermodynamics and kinetics. J. Hazard. Mater. 141, 77-85.
Artola, A., Rigola, M., 1999. Selection of optimum biological sludge for zinc removal from
wastewater by a biosorption process. Biotechnology Letters 14 (12), 1199.
Atul, K. K., Neha, G., and Chattopadhyaya, M.C., 2011. Adsorption behavior of Nickel (II) and
cobalt (II) onto hydrolyzed poly-methyl methacrylate. J. Chem. Pharm. Res.3, 807815.
Azouaoua, N., Sadaouia, Z., Djaafri, A., and Mokaddema, H., 2010. Adsorption of cadmium
from aqueous solution onto untreated coffee grounds: Equilibrium, kinetics and
thermodynamics. J. Hazard. Mater. 184, 126–134.
Azouaoua, N., Sadaouia, Z., Djaafri, A., Mokaddema, H., 2010. Adsorption of cadmium from
aqueous solution onto untreated coffee grounds: Equilibrium, kinetics and
thermodynamics. J. Hazard. Mater. 184,126–134.
Banum, S.J., 1982. Introduction to Organic and Biological Chemistry, third ed., Macmillan
Publishing Co., New York, NY, 541.
86
Bayat, B., 2002. Comparative study of adsorption properties of Turkish fly ashes I. The case of
nickel (II), copper (II) and zinc (II). J. Haz. Mat. B95, 251.
Beliles, R.P., 1979. The lesser metals, in: Oehme, F.W., (Ed.) Toxicity of heavy metals in the
environment, Part 2, Marcel Dekker, New York, 383.
Belkacem, M., Khodir, M., Abdelkrim, S., 2008. Treatment characteristics of textile wastewater
and removal of heavy metals using the electroflotation technique. Desalination 228,
245.
Benaïssa, H., and Elouchdi. M.A., 2007. Removal of copper ions from aqueous solutions by
dried sunflower leaves. Chem. Eng. Process. 46, 614–622.
Bitanihirwe, B.K., Cunningham, M.G., 2009. Zinc: The brain's dark horse. Synapse 63 (11),
1029.
Borba, C.E., Guirardello, R., Silva, E.A., Veit, M.T., Tavares, C.R.G., 2006. Removal of nickel
(II) ions from aqueous solution by biosorption in a fixed bed column: experimental
and theoretical breakthrough curves. Biochem. Eng. J. 30, 184-191.
Brown, P.H., Welch, R.M., Cary, E.E., 1987. Nickel: A micronutrient essential for higher plants.
Plant Physiol. 85, 801.
Camarilloa, R., Llanos, J., García-Fernández, L., and Pérez, Á, Cañizares, P., 2010. Treatment of
copper (II)-loaded aqueous nitrate solutions by polymer enhanced ultra filtration and
electrodeposition. Sep. Purif. Technol. 70, 320-328.
Can, M.Y., Yildiz, E., 2006. Phosphate removal from water by fly ash: factorial experimental
design. J. Hazard. Mater. 135, 165–170.
Canet, L., Ilpide, M., Seat, P., 2002.Efficient facilitated transport of lead, cadmium, zinc and
silver across a flat sheet-supported liquid membrane mediaed by lasalocid. A, Sep.
Sci. Technol. 37,1851–1860.
Casqueira, R.G., Torem, M.L., Kohler, H.M., 2006. The removal of zinc from liquid streams by
electroflotation. Miner. Eng. 19, 1388.
87
Cay, S., Uyanik, A., and Ozasik, A., 2004.Single and binary component adsorption on copper
(II) and cadmium (II) from aqueous solution using tea industry waste. Sep. Purif.
Techno. 38, 273–280.
Cesur, H., Balkaya, N., 2007. Zinc removal from aqueous solution using an industrial by-product
phosphogypsum, Chem. Eng. J. 131, 203.
Chang, J.H., Ellis, A.V., Yan., C.T., and Tung, C.H., 2009. The electrochemical phenomena and
kinetics of EDTA-copper waste water reclamation by electrodeposition and
ultrasound. Sep. Purif. Technol. 68, 216-221.
Chang, Q., Zhang, M., Wang, J.X., 2009. Removal of Cu2+ and turbidity from wastewater by
mercaptoacetyl chitosan. J. Hazard. Mater. 169, 621.
Charerntanyarak, L., 1999. Heavy metals removal by chemical coagulation and precipitation.
Wat. Sci. Technol. 39, 135.
Chen, Q.Y., Luo, Z., Hills, C., Xue, G., and Tyrer, M., 2009. Precipitation of heavy metals from
wastewater using simulated flue gas: sequent additions of fly ash, lime and carbon
dioxide. Water Res. 43, 2605-2614.
Chen, X., Jeyaseelan, S., and Graham, N., 2002. Physical and chemical properties study of the
activated carbon made from sewage sludge. Waste Manage. 22, 755-760.
Chih-Huang, W., 2002. Removal of Nickel (II) from Dilute Aqueous Solution by Sludge-Ash.
ASCE,128,716.
Cousins, R.I., 1996. Zinc. In: Present Knowledge in Nutrition. Ed. Zeigler, E.E., Filer, L.J., ILSI
Press, Washington DC.
Dahiya, S., Tripathi, R.M., and Hegde, A.G., 2008. Biosorption of lead and copper from aqueous
solutions by pretreated crab and arca shell biomass. Bioresour.Technol. 99: 179- 187.
88
Demirbas, E., Kobya, M., Öncel, S., and Sencan, S., 2002. Removal of Ni (II) from aqueous
solution by adsorption onto hazelnut shell activated carbon: equilibrium studies.
Bioresource Technol. 84, 291–293.
Doan, H.D., Lohi, A., Dang, V.B.H., and Dang-Vu, T., 2008. Removal of Zn+2 and Ni+2 by
adsorption in a fixed-bed of wheat straw. Process Saf Environ. 86, 259–267.
Doana, H.D., Lohi, A., Dang, V.B.H., and Dang-Vu. T., 2008. Removal of Zn+2 and Ni+2 by
adsorption in a fixed bed of wheat straw. Process Saf Environ. 6, 259–267.
Dobrevsky, I., Dimova-Todorova, M., and Panayotova, T., 1997. Electroplating rinse waste
water treatment by ion exchange. Desalination, 108, 277–280.
Doula, M.K., 2009. Simultaneous removal of Cu, Mn and Zn from drinking water with the use of
clinoptilolite and its Fe-modified form. Water. Res. 43, 3659.
Drinking Water Standards – In the Krewski et al Report 2001. Managing Health Risks from
Drinking Water: A Background Paper for the Walkerton Inquiry. Prepared on behalf
of the Ontario Water Works Association and the Ontario MunicipalWater
Association.
Dunnick, J.K., Elwell, M.R., Radovsky, A.E., Benson, J.M., Hahn, F.F., Nikula, K.J., Barr, E.B.,
Hobbs, C.H., 1995. Comparative carcinogenic effects of nickel subsulfide, nickel
oxide, or nickel sulfate hexahydrate chronic exposures in the lung. Cancer Res. 55
(22), 5251.
El-Ashtoukhy, E.-S.Z.,. Amin, N.K., Abdelwahab, O., 2008. Removal of lead (II) and copper (II)
from aqueous solution using pomegranate peel as a new adsorbent. Desalination. 223,
162–173.
El-Shafey, E.I., 2010. Removal of Zn (II) and Hg (II) from aqueous solution on a carbonaceous
sorbent chemically prepared from rice husk. J. Haz. Mat. 175, 319.
El-Shafey, I., Cox, M., Pichugin, A., and Appleton, Q., 2002. Application of a carbon sorbent for
the removal of cadmium and other heavy metal ions from aqueous solution. J. Chem.
Technol. Biotechnol. 77, 429–436.
89
Elshazly, A.H., and Konsowa, A.H., 2003. Removal of nickel ions from wastewater using a
cation-exchange resin in a batch-stirred tank reactor. Desalination. 158, 189-193.
Erol, P., and Turkan, A., 2007. Ion-exchange of Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ ions from
aqueous solution by Lewatit CNP 80. J. Hazard. Mater.140, 299-307.
Esalah, O.J., Weber, M.E., Vera, J.H., 2000. Removal of lead, cadmium and zinc from aqueous
solutions by precipitation with sodium di-(n-octyl) phosphinate. Can. J. Chem. Eng.
78, 948–954.
Escobar, C., Soto-Salazar, C., and Ine´ s Toral, M., 2006. Optimization of the electrocoagulation
process for the removal of copper. lead and cadmium in natural waters and simulated
wastewater. J Environ Manage. 81, 384-391.
Freundlich, H., and Heller, W., 1939. Rubber die adsorption in lusungen. J. Am. Chem. Soc. 61,
2228-2230.
Fu, F.L., Zeng, H.Y., Cai, Q.H., Qiu, R.L., Yu, J., and Xiong, Y., 2007. Effective removal of
coordinated
copper
from
wastewater
using
a
new
dithiocarbamate-type
supramolecular heavy metal precipitant. Chemosphere. 69, 1783-1789.
Fu, Y., and Viraraghavan, T., 2003. Column studies for biosorption of dyes from aqueous
solutions on immobilised Aspergillus niger fungal biomass. Water SA. 29, 465.
Gaikwad, W. G., 2011. Mass Transfer Studies on the Removal of Copper from Wastewater
Using Activated Carbon Derived from Coconut Shell. J. Univ. Chem Technol. Metall.
46, 1, 53-56.
Garg, U. K., Kaur, M.P., Garg, V.K., and Dhiraj, S. 2008. Removal of Nickel (II) from aqueous
solution by adsorption on agricultural waste biomass using a response surface
methodological approach. Bioresource Technol. 99, 1325–1331.
Ghassabzadeh, H., Mohadespour, A., Torab-Mostaedi, A., Zaheri, P., Mohammad, G. M., and
Hossein, T., 2010. Adsorption of Ag, Cu and Hg from aqueous solutions using
expanded perlite. J. Hazard. Mater. 177, 950–955.
90
Ghorai, S., and Pant, K.K., 2005. Equilibrium, kinetics and breakthrough studies for adsorption
of fluoride on activated alumina. Sep. Purif. Technol. 42, 265.
Ghosh, P., Samanta, A.N., Ray, S. Reduction of COD and removal of Zn2+ from rayon industry
wastewater by combined electro-Fenton treatment and chemical precipitation.
Desalination, (in press), doi:10.1016/j.desal.2010.08.029.
Gül, A., Yilmaz, M., Isilak, Z., 2009. Acute toxicity of zinc sulphate (ZnSO4·H2O) to Guppies
(Poecilia reticulata P., 1859). G.U. J. Sci. 22, 59-65.
Gupt, V.K., Arshi, R., Saini, V.K., and Neeraj, J., 2006. Biosorption of copper (II) from aqueous
solutions by Spirogyra species. J Colloid Interf Sci. 296, 59-63.
Haluk, A., Yasemin, B., and Çiğdem, Y., 2008. Removal of copper (II) from aqueous solution by
adsorption onto low-cost adsorbents. J. Environ. Manage. 87, 37–45.
Hambidge, K.M., Krebs, N.F., 2007. Zinc deficiency: a special challenge. J, Nutr. 137 (4), 1101.
Hani, A. Q., and Hassan, M., 2004. Removal of heavy metals from wastewater by membrane
processes: a comparative study. Desalination. 164, 105-110.
Hasar, H., 2003. Adsorption of nickel (II) from aqueous solution onto activated carbon prepared
from almond husk. J. Hazard. Mater. 97, 49-57.
Heidmann, I., and Calmano, W., 2010. Removal of Ni, Cu and Cr from a galvanic wastewater in
an electrocoagulation system with Fe- and Al-electrodes. Sep. Purif. Technol. 71,
308–314.
Heidmann, I., Calmano, W., 2008. Removal of Zn(II), Cu(II), Ni(II), Ag(I) and Cr(VI) present in
aqueous solutions by aluminium electrocoagulation. J. Hazard. Mater. 152, 934-941.
Helen, K., Karthik, B., and Lima, R.M., 2010. Removal and recovery of Ni and Zn from aqueous
solution using activated carbon from Hevea brasiliensis: Batch and column studies.
Colloids and Surfaces B: Biointerfaces. 78, 291–302.
Heyneman, C.A., 1996. Zinc deficiency and taste disorders. Ann. Pharmacother. 30,186.
91
Ho, Y.S., and McKay, G., 1999a. A kinetic study of dye sorption by biosorbent waste product
pith. Resour. Conserv. Recycl. 25, 171–193.
Hooper, P.L., Visconti, L., Garry, P.J., Johnson, G.E., 1980. Zinc lowers high-density
lipoprotein-cholesterol levels. J. Am. Med. Assoc. 244, 1960.
Hossain, S. M., and Anantharaman, N., 2005. Studies on Copper (II) Biosorption using
Thiobacillus ferrooxidans, J Univ Chem Technol and Metall, 40, 227-234.
Huang, J.H., Zeng, G.M., Zhou, C.F., Li, X., Shi, L.J., He, S.B., 2010. Adsorption of surfactant
micelles and Cd2þ/Zn2þ in micellar-enhanced ultrafiltration. J. Hazard. Mater. 183,
287.
Idris, A.M., Eltayeb, A.H., Potgieter-Vermaak, S.S., Van Grieken, R., Potgieter, J.H., 2004.
Assessment of heavy metals pollution in Sudanese harbours along the Red Sea Coast.
Microchem. J. 87, 104.
Ijagbemi, C.O., Baek, M.H., and Kim, D.S., 2009. Montmorillonite surface properties and
sorption characteristics for heavy metal removal from aqueous solutions. J. Hazard.
Mater. 166, 538–546.
Inbaraj, B.S., and Sulochana, N., 2006. Mercury adsorption on a carbon sorbent derived from
fruit shell of Terminaliacatappa. J. Hazard. Mater. 133, 283–290.
Institute of Medicine, Food and Nutrition Board. 2001. Dietary Reference Intakes for Vitamin A,
Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese,
Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National
Academy Press.
J. Crank, The Mathematics of Diffusion, 2nd Ed. Clarendon, Oxford, 1975.
Jaman, H., Chakraborty, D., and Saha, P., 2009. A Study of the Thermodynamics and Kinetics of
Copper Adsorption Using Chemically Modified Rice Husk. Clen. 37, 704–711.
Jiang, M., Wang, Q., Jin, X., and Chen, Z., 2009. Removal of Pb (II) from aqueous solution
using modified and unmodified kaolinite clay. J. Hazard. Mater. 170, 332–339.
92
Kabdas, I., Arslan, T., Ölmez-Hancı, T., Arslan-Alaton, I., Tünay, O., 2009. Complexing agent
and heavy metal removals from metal plating effluent by electrocoagulation with
stainless steel electrodes. J. Hazard. Mater. 165, 838.
Kadirvelu, K., 1998. Preparation and characterization of activated carbon, from coir pith and its
application to metal bearing wastewater. Ph.D. Thesis, Bharathiar University,
Coimbatore, India.
Kadirvelu, K., Thamaraiselvi, K., and Namasivayam, C., 2001. Removal of heavy metals from
industrial wastewaters by adsorption onto activated carbon prepared from an
agricultural solid waste. Bioresource Technol. 76, 63-65.
Kang, S.Y., Lee, J.U., Moon, S.H., Kim, K.W., 2004. Competitive adsorption characteristics of
Co2+, Ni2+, and Cr3+ by IRN-77 cation exchange resin in synthesized wastewater.
Chemosphere 56, 141e147.
Kannan, A., and Thambidurai, S., 2008. Comparative Studies on the Removal of Nickel (II) from
Aqueous Solution by Using Carbon Derived from Palmyra Palm Fruit Seeds and
Commercial Activated Carbon. Int J Sci & Technol. 1, 93-107.
Kasprzak, K.S., Sunderman Jr, F.W., Salnikow, K., 2003. Nickel carcinogenesis. Mutat. Res.
533 (1–2), 67.
Khelifa, A., Moulay, S., and Naceur, A.W., 2005. Treatment of metal finishing effluents by the
electroflotation technique. Desalination. 181, 27-33.
Khelifa, A., Moulay, S., Naceur, A.W., 2005. Treatment of metal finishing effluents by the
electroflotation technique. Desalination. 181, 27-33.
Krishnamurthy, C. R., Vishwanathan, P., 1991. Toxic metal in the Indian environment. Tata Mc
Graw Hill Publishing company Limited, New Delhi, 188.
Ku, Y., Jung, I.L., 2001. Photocatalytic reduction of Cr(VI) in aqueous solutions by UV
irradiation with the presence of titanium dioxide. Water. Res. 35, 135.
93
Kula, I., Ugurlu, M., Karaoglu, H., and Celik, A., 2008. Adsorption of Cd(II) ions from aqueous
solutions using activated carbon prepared from olive stone by ZnCl2 activation.
Bioresour. Technol. 99, 492–501.
Kumar, P. S., and Kirthika, K., 2009. Equilibrium and Kinetic Study of Adsorption of Nickel
from Aqueous Solution onto Bael Tree Leaf Powder. J. Sci. Eng. Techno. 4, 351 –
363.
Kumar, P. S., Ramakrishnan, K., Gayathri, R., 2010. Removal of Nickel (II) From Aqueous
Solutions by Ceralite IR 120 Cationic Exchange Resins. J. Sci. Eng. Techno. 5, 232 –
243.
Kwon, J.S., Yun, S.T., Lee, J.H., Kim, S.O., Jo, H.Y., 2010. Removal of divalent heavy metals
(Cd, Cu, Pb, and Zn) and arsenic (III) from aqueous solutions using scoria: Kinetics
and equilibria of sorption. J. Haz. Mat. 174, 307.
Landaburu-Aguirre, J., Pongrácz, E., Perämäk, P., Keiski, R.L., 2010. Micellar enhanced
ultrafiltration for the removal of cadmium and zinc: use of response surface
methodology to improve understanding of process performance and optimisation. J.
Hazard. Mater. 180, 524.
Langmuir, I., 1918. The adsorption of gases on plane surface of glass, mica and platinum. J. Am.
Chem. Soc. 40, 1361-1403.
Leyva Ramos, R., Bernal Jacome, L.A., Mendoza Barron, J.., Fuentes Rubio, L., Guerrero
Coronado, R.M., 2002. Adsorption of zinc (II) from an aqueous solution onto
activated carbon. J. Hazard. Mater. 90 (1), 27.
Liu, z.s., and Erhan, S.Z., 2001. Conversion of Soybean Oil into Ion Exchange Resins: Removal
of Copper (II), Nickel (II), and Cobalt (II) Ions from Dilute Aqueous Solution Using
Carboxylate- Containing Resin. J. Appl. Polym. Sci. 84, 2386-2396.
Lomaestro, B.M., Bailie, G.R., 1995. Absorption interactions with fluoroquinolones. Drug. Saf.
12, 314.
94
Manuela, D.M., Helena M.V.M.S., and Eduardo, V.S., 2010. Removal of Chromium, Copper,
and Nickel from an Electroplating Effluent Using a Flocculent Brewer‟s Yeast Strain
of Saccharomyces cerevisiae. Water Air Soil Pollut. 212, 199–204.
McKay, G., and Ho, Y.S., 1999b. The sorption of lead (II) on peat. Water Res. 33, 585–587.
McKay, G., and Ho, Y.S., 1999c. Pseudo second-order model for sorption processes. Process
Biochem. 34, 451–460.
Molinari, R., Poerio, T., and Argurio, P., 2008. Selective separation of copper (II) and nickel (II)
from aqueous media using the complexationeultra filtration process. Chemosphere.
70, 341-348.
Moniera, M., Ayad, D.M., Wei, Y., and Sarhan, A.A., 2010. Adsorption of Cu (II), Co (II), and
Ni (II) ions by modified magnetic chitosan chelating resin. J. Hazard. Mater.177 962–
970.
Muraleedharan, and Venkobachar, C., 1990. Mechanism of Biosorption of Copper (11) by
Ganoderma lucidum. Biotechnol. Bioeng. 35, 320-325.
Nafaˆa, A., Lotfi, M., Nizar, B., Jamel-Eddine, B., 2004. Teatment of electroplating wastewater
containing Cu2+, Zn2+ and Cr (VI) by electrocoagulation. J. Hazard. Mater. B112,
207–213.
Naim, R., Kisay, L., Park, J., Qaisar, M., .Zulfiqar, A.B., Noshin, M., and Jamil, K., 2010.
Precipitation Chelation of Cyanide Complexes in Electroplating Industry Wastewater.
Int. J. Environ. Res. 4,735-740.
Nakashima, A.S., Dyck, R.H., 2009. Zinc and cortical plasticity. Brain. Res. Rev. 59 (2), 347.
Nasir, M.H., Nadeem, R., Akhtar, K., Hanif, M.A., and Khalid, A.M., 2007.Efficacy of modified
distillation sludge of rose (Rosa centifolia) petals for lead (II) and zinc (II) removal
from aqueous solutions. J. Hazard.Mater. 147, 1006 – 1014.
95
National Council of the Environment – CONAMA, Government Resolution No. 357, Ministry of
the Environment, Brasília, Federal District, Brazil, (in Portuguese) 2005.
www.mma.gov.br/conama
Ngatenah, S. N. L., Kutty, S. R. M., and Isa, M. H., 2010. Optimization of Heavy Metal Removal
from Aqueous Solution Using Groundwater Treatment Plant Sludge (GWTPS),
International Conference on Environment 2010 (ICENV 2010) In: International
Conference on Environment (ICENV 2010), 13th - 15th December, 2010, Penang,
Malaysia.
Norton, L., Baskaran, K., and McKenzie, T., 2004. Biosorption of zinc from aqueous solutions
using biosolids, Adv. Environ. Res. 8, 629–635.
Norton, L., Baskaran, K., McKenzie, T., 2004. Biosorption of zinc from aqueous solutions using
biosolids. Adv. Environ. Res. 8 (3-4), 629.
Olayinka, K.O., Alo, B.I., Adu, T., 2007. Sorption of heavy metals from electroplating effluents
by low- cost adsorbents II: use of waste tea, coconut shell and coconut husk. J. App.
Sci. 7 (16), 2307.
Onundi, Y. B., Mamun, A.A., Al Khatib, M.F., and Ahmed, Y. M., 2010. Adsorption of copper,
nickel and lead ions from synthetic semiconductor industrial wastewater by palm
shell activated carbon. Int. J. Environ. Sci. Tech. 7, 751-758.
Onundi, Y.B., Mamuni, A.A., Al Khatibi, M.F., Ahmed, Y.M., 2010. Adsorption of copper,
nickel and lead ions from synthetic semiconductor industrial wastewater by palm
shell activated carbon. Int. J. Environ. Sci. Tech. 7, 751-758.
Orumwense, F.F.O., 1996. Removal of lead from water by adsorption on a kaolinitic clay. J.
Chem. Technol. Biotech. 65, 363–369.
Oyaro, N., Juddy, O., Murago, E.N.M., Gitonga, E., 2007. The contents of Pb, Cu, Zn and Cd in
meat in Nairobi, Kenya. Int. J. Food Agric. Environ. 5, 119-121.
96
Pairat, K., 2002. Biosorption of copper (II) from aqueous solutions by pre-treated biomass of
marine algae Padina sp. Chemosphere. 47, 1081-1085.
Papadopoulos, A., Fatta, D., Parperis, K., Mentzis, A., Harambous, K.J., and Loizidou, M., 2004.
Nickel uptake from a wastewater stream produced in a metal finishing industry by
combination of ion-exchange and precipitation methods. Sep. Purif. Technol. 39,181–
188.
Parameswari, E., Lakshmanan, A., and Thilagavathi, T., 2009. Biosorption of Chromium (VI)
and Nickel (II) by bacterial isolates from an Aqueous Solution. EJEAFChe. 8, 150156.
Patra, H.S., Sahoo B., and Mishra. B.K., 2009. Status of Sponge iron plants in Orissa. Research
Report
submitted
to
VASUNDHARA.
Available:http://www.vasundharaorissa.org/Research%20Reports/Status%20of%20sp
onge%20iron%20plant%20in%20Orissa.pdf
Paulino, A.T., Minasse, F.A.S., Guilherme, M.R., Reis, A.V., Muniz, E.C., Nozaki, J., 2006.
Novel adsorbent based on silkworm chrysalides for removal of heavy metals from
wastewaters. J. Colloid Interface Sci. 301, 479-487.
Pentari, D., Perdikatsis, V., Katsimicha, D., and Kanaki, A., 2009. Sorption properties of low
calorific value Greek lignites: removal of lead, cadmium, zinc and copper ions from
aqueous solutions. J. Hazard. Mater. 168, 1017–1021.
Pereira, F.V., Gurgel, L.V.A., de Aquino, S.F., and Gil, L.F., 2009. Removal of Zn2+ from
Electroplating Wastewater Using Modified Wood Sawdust and Sugarcane Bagasse,
ASCE. 135, 341-350.
Pereira, F.V., Gurgel, L.V.A., Gil, L.F., 2010. Removal of Zn2+ from aqueous single metal
solutions and electroplating wastewater with wood sawdust and sugarcane bagasse
modified with EDTA dianhydride (EDTAD). J. Haz. Mat. 176, 856.
Periasamy, K., and Namasivayam, C., 1995. Removal of nickel (II) from aqueous solution and
nickel plating industry wastewater using an agricultural waste: Peanut hulls. Waste
Manage, 15, 63-68.
97
Peric, J., Trgo, M., and Medvidovic, N.V., 2004. Removal of zinc, copper and lead by natural
zeolite-a comparison of adsorption isotherms. Water Res. 38, 1839–1899.
Pradhan, S., Shyam ,S.S., Kenneth, L.D., 2005. Removal of nickel from aqueous solutions using
crab shells. J. Hazard. Mater. B125, 201–204.
Prasad, A.S., 1995. Zinc: an overview. Nutrition 11, 93.
Prasad, A.S., 2008. Zinc in human health: effect of zinc on immune cells. Mol. Med. 14 (5–6),
353.
Prasad, A.S., Beck, F.W., Grabowski, S.M., Kaplan, J., Mathog, R.H., 1997. Zinc deficiency:
changes in cytokine production and T-cell subpopulations in patients with head and
neck cancer and in noncancer subjects. Proc. Assoc. Am. Physicians 109, 68.
Rathnakumar, S., Sheeja, R.Y., and Murugesan, T., 2009. Removal of Copper (II) from Aqueous
Solutions Using Teak (Tectona grandis L.f) Leaves, World Academy of Science,
Engineering and Technology 56.
Report Series in Radiochemistry 13/1999 Removal Of Harmful Metals From Metal Plating
Waste Waters Using Selective Ion Exchangers Heikki Leinonen University Of
Helsinki Faculty Of Science Department Of Chemistry Isbn 951-45-8759-6 (Pdf
Version) Issn 0358-7746 Helsinki 1999 Helsingin yliopiston verkkojulkaisut.
Sachin, M.K. and Gaikwad, R.W., 2011. Removal of zinc ions from industrial effluent by using
cork powder as adsorbent. Int. J. Chem. Eng. Appl. 2 (3), 199-201.
Sari, A., Tusen, M., Soylak, M., 2007. Adsorption of Pb(II) and Cr(III) from aqueous solution on
Celtek clay.J. Hazard. Mater. 144, 41–46.
Selvaraj, R., Jei-Won, Y., Younghun, K., Yongju, J., Yeong-Keong, H., and Won-Ho, K., 2007.
Adsorption characteristics of Cu (II) onto ion exchange resins 252H and 1500H:
Kinetics, isotherms and error analysis. J. Hazard. Mater.143, 469–477.
Shaker, M.A., 2007. Thermodynamic profile of some heavy metal ions adsorption onto
biomaterial surfaces. Am. J. App. Sci. 4 (8), 605.
98
Shankar, C., Sridevi, D., Joonhong, P., Michael, D., Kaliannan, T., 2007. Biosorption of
chromium and nickel by heavy metalresistant fungal and bacterial isolates. J. Hazard.
Mater. 146, 270–277.
Shrivastava A. K., 2009. A Review on Copper Pollution and its Removal from Water Bodies by
pollution Control Technologies. IJEP. 29, 552-560.
Shukla, S.R., Pai, R.S., 2005. Adsorption of Cu (II), Ni (II) and Zn (II) on dye loaded groundnut
shells and sawdust. Sep. Purif. Technol. 43, 1.
Shyam, S.S., Li, J.Y., Kenneth, L.D., Alka, S., 2005. Removal of nickel from aqueous solutions
by sawdust. J. Hazard. Mater. B121, 243–246.
Sigel, A., Sigel, H.., Sigel, R. K.O., 2008. Nickel and Its Surprising Impact in Nature. Metal Ions
in Life Sciences. 2. Wiley, 728.
Smiciklas, I.D, Milonjic, S.K., Pfendt, P., and Raičević, S., 2000. The point of zero charge and
sorption of cadmium (II) and strontium (II) ions on synthetic hydroxyapatite. Sep.
Purif. Technol.18, 185–194.
SolmazKarabulut, ¨lkerimKarabakan, A., Denizli, A., and Yu¨ru¨m, Y., 2000. Batch removal of
copper (II) and zinc (II) from aqueous solutions with low-rank Turkish coals. Sep.
Purif.Technol. 18, 177–184.
Solomons, N.W., 1998. Mild human zinc deficiency produces an imbalance between cellmediated and humoral immunity. Nutr. Rev. 56, 27.
Srisuwan, G., and Thongchai, P., 2002. Removal of heavy metals from electroplating wastewater
by membrane Songklanakarin. J. Sci. Technol. 24, 965-976.
Srivastava, N.K., Majumder, C.B., 2008. Novel biofiltration methods for the treatment of heavy
metals from industrial wastewater. J. Hazard. Mater. 151, 1-8.
99
Srivastava, V.C., Mall, I.D., and Mishra I.M., 2006. Characterization of mesoporous rice husk
ash (RHA) and adsorption kinetics of metal ions from aqueous solution onto RHA. J.
Hazard. Mater. 134, 257–267.
Sugarman, B., 1983.Zinc's role in microorganisms is particularly reviewed in: "Zinc and
infection". Review of Infectious Diseases 5, 137.
Tanninen, J., Mänttäri, M., and Nyström, M., 2006. Nano filtration of concentrated acidic copper
sulphate solutions. Desalination. 189, 92-96.
Tariq, S. N., Nazik, J. E., and Dawood, A. A., 2009. Adsorption of Copper and Iron Using Low
Cost Material as Adsorbent. E-J. Che. 6, 161-168.
Teker, M., and Imamo Glu, M., 1999. Adsorption of Copper and Cadmium ions by Activated
Carbon From Rice Hulls. Turk J Chem. 23, 185- 191.
Temkin, M.I., and Pyzhev, V., 1940. Kinetics of ammonia synthesison promoted iron catalysts,
Acta Physiochim. URSS.12, 327-356.
Treybal, R.E., 1981. Mass Transfer Operations, Third ed., McGraw Hill International Editions.
Urano, K., Tachikawa, H., 1991. Process development for removal and recovery of phosphorus
from wastewater by a new adsorbent. Ind. Eng. Chem. Res. 30, 1893.
Vijayakumaran, V., Arivoli S., and Ramuthai, S., 2009. Adsorption of Nickel Ion by Low Cost
Carbon-Kinetic, Thermodynamic and Equilibrium Studies. E-J Che. 6, 347-357.
Vijayaraghavan, K., Jegan, J., Palanivelu, K., Velan, M., 2004. Removal of nickel (II) ions from
aqueous solution using crab shell particles in a packed bed up-flow column. J.
Hazard. Mater. B113, 223–230.
Vilar, V.J.P., Botelho, C.M.S, and Boaventura, A.A.R., 2008. Copper removal by algae
Gelidium, agar extraction algal waste and granulated algal waste: Kinetics and
equilibrium. Bioresour. Technol. 99, 750-762.
100
Vinke, P., Van der Eijk, M., Verbree, M., Voskamp, A.J. ,and Van, Bekkum, H., 1994
Modification of the surfaces of a gasactivated carbon and a chemically activated
carbon with nitric acid, hypochlorite, and ammonia. Carbon. 32, 675-686.
Volesky, B., and Prasetyo, I., 1994. Cadmium removal in a biosorption column. Biotechnol.
Bioeng. 43, 1010.
Volesky, B., Weber, J. and Park, J.M., Continuous flow metal biosorption in a regenerable
Sargassum column, Water Res., 2003, 37 297-306.
Wang, L.K., Hung, Y.T., Shammas, N.K., 2007. Advanced physicochemical treatment
technologies. In: Handbook of Environmental Engineering, 5. Humana, New Jersey.
Wasewar, K.L., 2010. Adsorption of metals onto tea factory waste: A review, IJRRAS 3, 303322.
Weber Jr, W.J., and Morris, J.C., 1963. Kinetics of sorption of carbon from solution. J. Saint.
Eng. Div. Am. Soc. Civil Engineers. 89, 2.
Wilson, J.A., Pulford, I.D., and Thomas, S., 2003. Sorption of Cu and Zn by Bone Charcoal.
Environ. Geochem. Health. 25, 51–56.
Wong, P. K., and Fung, K. Y., 1997. Removal and recovery of nickel ion (Ni2+) from aqueous
solution by magnetite-immobilized cells of Enterobacter sp. 4-2. Enzyme Microb
Tech. 20, 116-121.
Yao, Z.Y., Qi, J.H., Wang. L.H., 2010. Equilibrium, kinetic and thermodynamic studies on the
biosorption of Cu (II) onto chestnut shell. J. Hazard. Mater. 174, 137–143.
Yeddou Mezenner, N., and Bensmaili, A., 2009. Kinetics and thermodynamic study of phosphate
adsorption on iron hydroxide- eggshell waste. Chem. Eng. J. 147, 87–96.
Yu Ji. Simultaneous adsorption of nickel ions and humic acid onto an activated carbon.
Department of Environmental Science and Engineering, National University of
Singapore,
10
Kent
Ridge
Crescent,
119260
Singapore
www.nus.edu.sg/nurop/2010/Proceedings/FoE/Yu%20Ji.pdf.
101
Yu, B., Zhang, Y., Shukla, A., Shyam, S. S., Kenneth, L. D., 2000. The removal of heavy metal
from aqueous solutions by sawdust adsorption-removal of copper. J. Hazard. Mater.
B80, 33–42.
Zhang, L.N., Wu, Y.J., Qu, X.Y., Li, Z.S., and Ni, J.R., 2009. Mechanism of combination
membrane and electro-winning process on treatment and remediation of Cu2+ polluted
water body. J. Environ. Sci. 21, 764-769.
Zhao, G., Zhang, H., Fan, F., Li, X.R. J., and Wang, Y. C. X., 2010. Sorption of copper (II) onto
super-adsorbent of bentonite–polyacrylamide composites. J. Hazard. Mater. 173,
661–668.
Zouboulis, A.I., Matis, K.A., Lanara, B.G., Neskovic, C.L., 1997.Removal of cadmium from
dilute solutions by hydroxy apatite. II. floatation studies, Sep. Sci. Technol. 32, 17551767.
102
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