TABLE OF CONTENTS
Title – – – – – – – – – – i
Approval – – – – – – – – – – ii
Certification – – – – – – – – – íii
Declaration – – – – – – – – – iv
Dedication – – – – – – – – – – v
Acknowledgment – – – – – – – – – vi
Abstract – – – – – – – – – – vii
Table of contents – – – – – – – – – viii-xiv
List of abbreviations- – – – – – – – – – xv
List of table – – – – – – – – – – xvi-xvii
List of figures – – – – – – – – – – xviii-xx
List of symbols – – – – – – – – – xxi-xxii
List of Schemes – – – – – – – – – xxiii
CHAPTER ONE
1.0. Introduction – – – – – – – – 1
1.1 Background of the Study – – – – – – – 1
1.2. Statement of the Problem – – – – – – – 4
1.3. The Justification of the Research- – – – – – – 4
1.4. Aims and Objectives of the Research – – – – – 5
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CHAPTER TWO
2.0 Literature Review – – – – – – – – .6
2.1 Review of some work Related to this Research – – – – 6
2.2 Heavy metals – – – – – – – – – 12
2.2.1 Beneficial Heavy Metals – – – – – – – 12
2.2.2 Toxic Heavy Metals – – – – – – – 13
2.2.3 Cadmium – – – – – – – – 13
2.2.4 Properties of cadmium – – – – – – 14
2.2.5 Applications – – – – – – – – 14
2.2.6 Health effects of Cadmium – – – – – – 15
2.2.7 Lead – – – – – – – – – 15
2.2.8 Properties of lead – – – – – – – 17
2.2.9 Applications – – – – – – – – 17
2.2.10 Health effects of lead – – – – – – – 18
2.2.11 Nickel – – – – – – – – 19
2.2.12 Properties of Nikel – – – – – – – 19
2.2.13 Applications – – – – – – – 20
2.2.14 Health effect of Nikel – – – – – – .20
2.3 Pollution by Cd2+, Ni2+ and Pd2+ – – – – – – 22
2.3.1 Cadmium in the environment – – – – – – 22
2.3.2 Environmental effects of cadmium – – – – – – 23
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2.3.3 Lead in the environment – – – – – – 24
2.3.4 Environmental effects of lead – – – – – – 24
2.3.5 Nikel in the environment – – – – – – 25
2.3.6 Effects of nickel on the environment – – – – – 25
2.3.7 Atomic Absorption Spectroscopy (AAS) – – – – 26
2.4 Adsorption Mechanism – – – – – – 29
2.4.1 What is Adsorption? – – – – – – – 29
2.4.2 How Adsorption occurs – – – – – – 29
2.4.3 Adsorption occurs – – – – – – – 30
2.4.4 Adsorption in solids – – – – – – – 30
2.4.5 Facts about Adsorption Process – – – – – 31
2.4.6 Type of Adsorption – – – – – – – 32
2.4.7 Applications of Adsorption – – – – – – 35
2.4.8 Factors on which Adsorption Depends – – – – 37
2.5.0 Adsorption Isotherm – – – – – – – 38
2.5.1 The Langmuir isotherm – – – – – – 38
2.5.2 The Freundlick isotherm – – – – – – 39
2.6 Displacement of Adsorbed Metals by Competitive Ions in Solution – – 41
2.7 The Ligand; Azo Ligand – – – – – – 42
2.7.1 Definition – – – – – – – – 42
2.7.2 Diazotization – – – – – – – – 42
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2.7.3 Azo Coupling – – – – – – – 43
2.7.4 4-Amionantipyrine – – – – – – – 43
2.7.5 Properties of 4- Amionantipyrine – – – – – 43
2.7.6 Pyrogallol – – – – – – – – 44
2.7.7 Properties of pyrogallol – – – – – – 44
2.8 Activated Carbon – – – – – – – 45
2.8.1 Definition of activated Carbon – – – – – 45
2.8.2 Historical Development of Activated Carbon- – – – 46
2.8.3 Properties of Activated Charcoal – – – – – 47
2.8.4 Chemical properties of Activated Carbon – – – – 52
2.8.5 Classification – – – – – – – – 54
2.8.6 Applications of Activated Charcoal – – – – – 57
2.8.7 Factors in which Selection of Raw Material Depends on – – 61
2.8.8 The Coconut Shell – – – – – – – 61
2.8.9 Uses of Coconut Shell Activated Carbon and its Advantages
over other ACs – – – – – – – 64
2.8.10 Activation of Coconut Shell Carbon – – – – – 64
CHAPTER THREE
3.0 Materials and Methods – – – – – – – 66
3.1 Apparatus – – – – – – – – – 66
3.2 Preparation of Reagents – – – – – – – 66
xii
3.2.1 Reagents- – – – – – – – – – 66
3.2.2 Preparation of 0.5 Moldm-3 of CH3COOH (Acetic Acid) – – – 67
3.2.3 Preparation of 0.5 Moldm-3 of HNO3 – – – – – – 67
3.2.4 Preparation of 1000 ppm Pb(NO3)2 solution – – – – – 67
3.2.5 Preparation of 1000 ppm Cd(NO3)2 4H2O solution – – – – 67
3.2.6 Preparation of 1000ppm NiCl2. 6H2O solution – – – – 68
3.3. Synthesis of the Ligand – – – – – – – 68
3.4 Production of Coconut Shell Activated Carbon Modified, MCSAC – – 70
3.4.1 Experimental procedure for CSAC-M – – – – – 70
3.4.2 Gathering of Coconut (Cocos Nucifera) Shell- – – – – 70
3.4.3 Preparatory Stage (preparing it for carbonization) – – – – 71
3.4.4 Carbonization- – – – – – – – – 71
3.4.5 Activation (Chemical activation) – – – – – – 71
3.4.6 Modification with azo ligand; 1, 2-Dihdroxy-1,5-dimethyl-2-pheny
l-4-(E)- (2,3,4-Trihydroxyphenyl) -3H-pyrazol-3 one, (DDPTP) – – 71
3.5.0 Characterization of the modified Coconut Shell Activated Carbon – 72
3.5.1 Determination of the moisture content – – – – – 72
3.5.2 pH measurement – – – – – – – – 72
3.5.3 The Determination of bulk density – – – – – – 72
3.5.4 Ash Content Determination- – – – – – – 73
3.5.5 Pore Volume Determination (PV)- – – – – – – 73
xiii
3.5.6 Determination of volatile matter – – – – – – 73
3.5.7 Adsorption procedure – – – – – – – 74
3.6 Adsorption Procedure – – – – – – – 74
3.6.1 Experimental Procedure – – – – – – – 74
3.6.2 Variation of initial metal ion concentration- — – – – 75
3.6.3 Variation of contact time – – – – – – – 75
3.6.4 Variation of temperature of carbonization – – – – – 75
3.6.5 Variation of pH value – – – – – – – 75
3.6.6 Variation of particle size – – – – — – – 76
3.6.7 Variation of ligand amount – – – – – – – 76
3.6.8 Variation of level of treatment of adsorbent on adsorption- – – 76
3.6.9 Competitive adsorption – – – – – – – 77
CHAPTER FOUR
4.0 Results and Discussions – – – – – – – 78
4.1 Physical Characterization and Molar Conductivity Data of the Ligand – 78
4.2 Electronic Spectra of the Azoligand – – – – – 78
4.3 FTIR Spectra of the Azoligand – – – – – – 79
4.4 Physico-Chemical properties of the Adsorbent – – – – 81
4.5 Adsorption – – – – – – – – – 91
4.5.1 Effect of Concentration on the removal of Pb2+, Cd2+, and Ni2+ from solutions- 91
4.5.2 Effects of contact time on the Removal of Pb2+, Cd2+, and Ni2+ from solutions-92
xiv
4.5.3 Effects of temperature of carbonization on the sorption capacity of the adsorbent-94
4.5.4 Effect of pH on the removal of Pb2+, Cd2+, and Ni2+ from solutions- – -95
4.5.5 Effects of degree of treatment of adsorbent (MCSAC)- – – – 96
4.5.6 Effects of amount of Ligand on Adsorption of Pb2+, Cd2+, and Ni2+ – – 98
4.5.7 Effects of particle adsorption of Pb2+, Cd2+, and Ni2+ – – – – 99
4.5.8 Competitive adsorption of Pb2+, Cd2+, and Ni2+ from their
mixed solution on MCSA- – – – – – – – .100
4.6 Adsorption Isotherm – – – – – – – 101
4.6.1 The Langmuir Isotherm – – – – – – – 101
4.6.2 The Freundlich Isotherm – – – – – – – 103
4.7 Kinetic Study – – – – – – – – 105
4.7.1 The pseudo- first –order – – – – – – – 105
4.7.2 The pseudo-second-order kinetics – – – – – – 107
4.7.3 Intraparticle Diffusion Model – – – – – – 108
4.8 Conclusions – – – – – – – – – 111
4.9 Recommendation – – – – – – – – 112
References – – – – – – – – -113-124
CHAPTER ONE
1.0 Introduction
1.1 Background of the Study
The presence of trace heavy metals in natural water has aroused the interest of many Nigerian
scientists as a result of their environmental effects on the health of both plants and animals. More
so, concerns about environmental protection has increased due to the technology1 development
which keeps on changing, producing industrial product, as well as waste. Manufacturing
industries have played an important role for economic growth in major countries. This sector
provides services and product for better way and quality of life. However, rapid change in
industrialization produces vast amount of waste and will cause harm and deterioration of the
environment and ecosystem if improperly managed. Pollutants from textiles industry was
declared as one of the major sources of wastewater in Asian country1 as it is considered as
possible carcinogenic or mutagen. Apart from that, heavy metals such as cadmium, chromium,
lead, copper, manganese, zinc as well as mercury and nickel are widely discharged in the
wastewater from industries and are very toxic and harmful to living organisms by lowering the
reproductive success, preventing proper growth and even causing death2. Some of the heavy
metals are important for our body requirement; however exceeding the tolerance limit may create
harm to body functions.
The most toxic heavy metals are Cd, Pb and Hg ions due to their high attraction for sulphur
which will disturb enzyme function by forming bon d with sulphur. The ions will hinder the
transport process through the cell wall, thereby disturbing the cell function. Other pollutants
from the industries are phenol; from refineries, petrochemical wastewater, pulp mills and coal
mines. Presence of phenols in water bodies caused carbolic odor to receiving water bodies, thus
causing toxic effects on aquatic flora and fauna3. Apart from that it is also toxic to humans and
affects several biochemical functions4.
Unlike organic pollutants, heavy metals do not biodegrade and thus, pose a different kind of
challenge for remediation. To alleviate the problem of water pollution by heavy metals, various
2
methods have been used to remove them from waste water such as chemical precipitation,
coagulation, floatation, adsorption, ion exchange, reverse osmosis and electrodialysis5-7. The
production of the sludge in the precipitation methods poses challenges in handling treatment and
hand filling of the solid sludge. Ion exchange usually requires a high – capital investment for the
equipment as well as high operational cost. Electrolysis allows the removal of metal ions with
the advantage that there is no need for additional chemicals and also there is no sludge
generation. However, it is inefficient at a low metal concentration. Membrane processes such as
reverse osmosis and electrodialysis tend to suffer from the in-stability of the membranes in salty
or acidic conditions and fouling by inorganic and organic substances present in waste water8.
Most of these techniques have some pretreatments and additional treatments. In addition, some
of them are less effective and require high cost9.
It was only in the 1990s that a new scientific area, biosorption was developed that could help in
the recovery of heavy metals. The first reports described how abundant biological materials
could be used to remove, at very low cost, even small amounts of toxic heavy metals from
industrial effluents9-11. Metal-sequestering properties of non-viable microbial biomass provide a
basis for the removal of heavy metals when they occur at low concentrations9. Therefore, many
researchers have applied regenerated wastes to treat heavy metals from aqueous solutions.
The main objective of the method is to treat the wastewater before discharging to water source,
thus decreasing the threat and deterioration to the environment and promising better
sustainability of the environment. There are many technologies that have been developed for
purification and treatment of waste water including chemical precipitation, solvent extraction,
oxidation, reduction, dialysis/electro dialysis, electrolytic extraction, reverse osmosis, ionexchange,
evaporation, cementation, dilution, adsorption, filtration, floatation, air stripping,
steam stripping, flocculation, sedimentation and soil flushing/washing chelation12. The selection
technologies must be analyzed accordingly based on several factors such as available space for
construction of treatment facilities, ability of process equipment, limitation of waste disposal,
desired final water quality and cost of operation. Mostly, all the technologies listed above are
less likely to be selected because they required large financial input and their applications are
limited due to the associated cost factors. Adsorption process is found to be the most suitable
3
technique to remove pollutants from wastewater. It is mostly preferred due to its convenience,
ease of operation and simplicity of design. Apart from removing many types of pollutants, it also
has wide application in water pollution control. Activated carbon (AC) is widely used as
absorbent due to its high surface area and pore volume as well as inert properties. However,
conventional AC is expensive due to the depletion of coal-based source and especially for
producing high quality AC13.
To counter the high cost of AC, low cost precursors have been of high interest for researchers to
replace the conventional AC. The factors affecting substitution of raw material are high carbon
content, low inorganic content, high density and sufficient volatile content, stability of supply in
the countries, potential extent of activation and inexpensive material6. The AC is mainly
comprised of carbon with large surface area, large pore volume and porosity where the
adsorptions take place.
There are some reviews reporting the use of coconut and palm shell for the production of AC14;
however such studies are restricted to either type of wastes, preparation procedures, or specific
aqueous-phase applications. But, due to the abundant source of precursors, with high volatile,
carbon contents, and hardness; coconut shells are an excellent raw material source to produce
activated carbon suitable to replace conventional AC14. Moreover, this can be said to be,
“substitution of waste to wealth”. The adsorption capacity of the adsorbent could be improved by
its modification. This is because; the functional groups on the surface of the AC could be
improved by modification with a ligand that has electron donating groups like hydroxyl group,
amide group, etc.
It is the aim of the research to adsorb Pd2+, Cd2+ and Ni2+ from waste water sample on locally
prepared activated charcoal from coconut shell modified with an azo ligand; 1,2 –dihydro -1,5-
dimethyl-2-phenyl-4-(E)- (2,3,4-trihydrophenyl)-3H-pyrazol-3-one (DDPTP).
4
1.2. Statement of the Problem
i. In a developing country, the technology development keeps on changing, producing
industrial product, as well as waste. Also, rapid growth in industry produces vast amount
of waste and causes harm and deterioration of the environment and ecosystem.
ii. These wastes enter the water body to cause water pollution and therefore must be treated
before it is used domestically or otherwise.
iii. Many techniques have been employed for this treatment but they are less likely to be
selected because they required large financial input and their applications are limited due
to the associated cost factors.
iv. Adsorption process is found to be the most suitable technique to remove pollutants from
wastewater due to its convenience, ease of operation and simplicity of design.
Conventional AC could not see to that because it is expensive due to the depletion of
coal-based source and especially for producing high quality AC13.
v. Many industries and individuals discard coconut shell as wastes and this local agricultural
waste could cause environmental nuisance.
vi. Coconut shell has been used for the production activated carbon but the modification of
this adsorbent made from coconut shell with a ligand has not been executed.
1.3. The Justification of the Research
The world production of AC in 1990 was estimated to be 375,000 ton, excluding what was then
Eastern Europe and also China. In 2002, the demand for activated carbon reached 200,000 ton
per year in United States. The demands for AC were increased over the years from 2003 and
market growth was estimated at 4.6 % per year. The strong market position held by AC relates to
their unique properties and low cost compared with that of possible competitive inorganic
adsorbents like zeolites6. AC is used primarily as an adsorbent to remove organic compounds
and pollutant from liquid and gas streams. The market has been increasing constantly as a
consequence of environmental issues, especially water and air purification. Furthermore, as more
and more countries are becoming industrialized, the need for activated carbon to comply with
environmental regulation will grow at faster rate. Liquid phase applications represent the largest
5
outlet for AC. In these applications, AC is used in the purification of a variety of liquid streams,
such as those used in water and the processing of food, beverages and pharmaceuticals. The
growth of the activated carbon market in the last two decades in the most industrialized region
will very probably continue in the near future as more developing areas of the world will realized
the importance of controlling water and air pollution. This demand can be satisfied considering
the large number of raw material available for the production of AC, the variety of activation
processes described, and the available forms of AC6. This is why we ventured into the
modification of coconut shell activated carbon to study its potential in controlling water
treatment.
1.4. Aims and Objectives of the Research
The aim of this research is to investigate the sorption capacity of modified coconut shell
activated carbon (MCSAC) for the removal of Pb2+, Cd2+ and Ni2+ from polluted water. The
charcoal was activated with an activating agent (CaCO3) and modified with an azo ligand; 1,2
dihydro-1,5-dimethy1-2phenyl-4-(E)–(2,3,4-trihydroxyphenyl)–3H-pyrazol-3-one (DDPTP) in
order to improve its adsorption capacity and used to adsorb trace heavy metals; Cd2+, Pb2+, and
Ni2+ from synthetic water sample. To achieve these, studies were carried out with the following
objectives:
I. Production of activation carbon from coconut shell using calcium carbonate as the
activating agent.
II. Modification of the coconut shell activated carbon with an azo ligand: 1,2-dihydro-
1,5-dimethyl-2-phenyl-4-(E)-(2,3,4-trihydroxylphenyl)-3H-pyrazol-3-one (DDPTP).
III. Evaluation of the adsorption potentials of the adsorbent with respect to Pb2+, Cd2+ and
Ni2+.
IV. Evaluation of the influences of the analytical parameters like pH, temperature of
carbonization, equilibration time(contact time), initial concentration of the metal ions,
ligand amount, particle sizes, degree of treatment of adsorbent.
V. To study the adsorption isotherms and adsorption kinetics of the adsorption process.
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