THE COPPERBELT UNIVERSITY

SCHOOL OF MATHEMATICS AND NATURAL SCIENCES

DEPARTMENT OF CHEMISTRY

REMOVAL OF SULFATES FROM WASTE WATER

USING
NATURAL CLAY SOIL
A DESERTATION SUBMITTED TO THE COPPERBELT UNVERSITY IN FULFILMENT OF
THE REQUIREMENT FOR THE DEGREE OF BACHELOR OF CHEMISTRY

BY

SICHIVULA COBBY
STUDENT NUMBER: 15004594

SUPERVISOR: DR. K. KALEBAILA

Kitwe. 2019.
Contents
Acronyms and abbreviations..................................................................................................................... 4
Declaration ................................................................................................................................................ 5
Dedication ................................................................................................................................................. 6
Acknowledgement .................................................................................................................................... 7
Abstract ..................................................................................................................................................... 8
Chapter One .............................................................................................................................................. 9
1.1 Introduction ......................................................................................................................................... 9
1.2 Problem Statement ............................................................................................................................ 10
1.3 Problem Justification .................................................................................................................. 10
1.4 Objectives ................................................................................................................................... 11
1.5 Research Questions ..................................................................................................................... 11
Chapter Two............................................................................................................................................ 12
2.1 Background and Literature review .............................................................................................. 12
Chapter Three.......................................................................................................................................... 16
Methodology: .......................................................................................................................................... 16
3.1 Materials required for the preparation of Standard sample. .............................................................. 16
Apparatus Required ................................................................................................................................ 16
Chemicals Required ................................................................................................................................ 16
3.2 Preparation of Standard samples of sulfates (SO42-): ........................................................................ 16
Standard stock sulfate solution ............................................................................................................... 16
Conditioning Reagent ................................................................................ Error! Bookmark not defined.
3.3 Preparation of Blank and 4 Standard samples for Testing ................................................................ 17
UV- spectrometer and Spectra Manager – software. .............................................................................. 17
3.3.1 Standard Sample Testing ............................................................................................................... 17
First Run of Standards ................................................................................ Error! Bookmark not defined.
Second Run of Standards ........................................................................... Error! Bookmark not defined.
3.4 Materials required for preparation of Sample. Kaolinite (Clay Soil), ............................................... 18
3.4.1 Preparation of Sample .................................................................................................................... 18
3.4.2 Sample Testing............................................................................................................................... 18
Chapter Four ........................................................................................................................................... 20
4.1 Data Analysis .............................................................................................................................. 20
4.2 Results ......................................................................................................................................... 22
5 References ........................................................................................................................................... 24
Acronyms and abbreviations

VOCS – Volatile Organic Compounds

CERS
IX -
WHO – World Health Organization
ZABS – Zambia Bureau of Standards
AMD – Acid Mine Drainage
Declaration
I Sichivula Cobby, declare this dissertation as an original work of my Research. Clear reference
has been indicated wherever contribution of others is involved with due to the literature Review,
and collaborative research and discussions.

Sichivula Cobby

Signature: ……………………………………………
Date: …………………………………………………

Supervisor:

Dr. Kabaso Kalebaila

Signature: ……………………………………………
Date: …………………………………………………

Kitwe, Zambia.
Dedication
I dedicate this work to my parents Mr. Gilbert C. Sichivula and Mrs. Patricia M. Sichivula and
my Siblings. I thank God for your unconditional Support and Love you show to me in
everything. May the good Lord Bless you.
Acknowledgement
Firstly, I have to give my sincere gratitude to the Great Yahweh for His abundance Grace and
Power. I thank you Jehovah for your Strength and ever abiding Grace you bestowed upon my life
and most importantly, my academic life.
Secondly, Thanks to my mentor and Lecturer Dr. Kabaso K. Kalebaila (Chemistry Department)
at the Copperbelt University, Kitwe main campus for his guidance, knowledge, encouragements,
corrections and every support he rendered to me to make the dissertation of this piece a reality.
Thirdly, I take this opportunity to also Thank My Lecturers Mr. P. S. Daka (Project Coordinator),
Dr. I Singh (The Head of Chemistry Department), Dr. Salia Lwenje (HSRIP) and the entire
School of Mathematics and Natural Sciences for the knowledge impacted in me since my first
year of study.
I would also like to thank the Copperbelt University Chemistry Laboratory as well as
Environmental Laboratory Technicians who helped me during my Lab works even for organized
and conducive environment during my research. May God bless you!
Great appreciation to my family, most importantly my parents for unconditional Love and
support. Not forgetting My Uncle Mr. Jackson Sichivula and his family. To My Siblings, Mr.
Cephas Sichivula, and the rest of the team you are the reason I get up every time I fall!
Lastly, my special thanks goes to my close friends who provided courage when I needed it, Mr.
Mukelabai Mubiana, Mr. Sydney Siame (Ba Staff) and all my Classmates together with my
colleagues Mr. Lloyd Kojhi and Ms. Gloria Mutale. Job well done to all of you guys….!
Abstract
Chapter One
1.1 Introduction
Water is the basic element for human survival together with other animals. Almost all human
operations are dependent on the use of Water and its known that about 70% of the human body is
made of Water. The importance of Water stretches also to other living things for their survival.
In industries, Water is used for cooling down heated machines, as solvent for various industrial
processes, for driving waste materials from the industries etc. Domestically, Water is used for
cooking, washing, cleaning, drinking etc.
However, due to some of these uses of water alluded above, the freshwaters ends up been
contaminated. Depending on the usage, Water is contaminated with various contaminants .i.e.
Nitrates, Sulfates and Phosphates. These are water contaminants from fertilizers applied in farms
taken into the rivers by the run-off Water from the farms. Sulfates are also traced in the
Pesticides applied on the crops which are also taken along with the run-off Water into the rivers.
Other contaminants such as Heavy Metals are deposited into the rivers from the mining
industries and other manufacturing Industries by wastewaters released from these Industries.
Other contaminants such as Volatile Organic Compounds (VOCs) are mainly from detergents,
cosmetic and other domestic products which are also deposited into the rivers.
This research focuses on the removal of Sulfates from the wastewaters using natural clay soil
which is abundantly available in Zambia. This can be the cheapest method of removing Sulfates
from the wastewaters as it uses the typical phenomenon called Adsorption, to remove Sulfates
from the water.
Adsorption is the surface phenomenon by which species stick on the surface of the other
substance without penetrating through the substance. Commonly the removal of Sulfates calls for
very complicated and expensive techniques to remove Sulfates from drinking water or
wastewaters. The expensive techniques that are commonly used to remove Sulfates are Nano-
filtration, Reverse Osmosis, ion exchange (IX) Electro-dialysis and Cost Effective Sulfates
Removal (CESR) process.
The research is very important to consider especially in Zambia as a developing country. Due to
the high costs of the techniques commonly used to remove Sulfates, Zambian Companies such as
water utility companies among others may not be able to afford to remove sulfates to meet the
standard concentration of Sulfates in Drinking water as per World Health Organization, WHO
and Zambia Bureau of Standards, ZABS. For this reason, this research brings about hope to be
able to remove Sulfates from drinking water and/or Wastewater using a very cheap method of
using natural clay soil by adsorption.
 1.2 Problem Statement
The presence of excess Sulfates (Nutrients) in Rivers such as Kafubu River in Ndola district and
Kafue River in Kafue district triggers the natural process known as Eutrophication.
Eutrophication is the process of rapid growth of plants (Algae and weed) in the water bodies as a
result of Compounds (Nutrients) from fertilizer such as phosphates, nitrates and Sulfates. The
algae grow by photosynthesis which uses carbon dioxide producing Oxygen. In the presence of
Oxygen, when the plants dies they decompose due to aerobic bacterial and fungal activities in the
river bodies which later causes anoxia thereby killing the aquatic organisms. The Kafubu River
is the source of water for the people of Ndola and Luanshya and the presence of these
contaminants renders the quality of water for various uses unacceptable. Also Sulfates in water
above the permitted level cause abdominal pain, laxative effects and also causes bad taste and
odor in drinking water. In the past few years, people of Ndola complained of the effects of these
contaminants as reported in the post newspaper dated xx/xx/xxxx.

1.3 Problem Justification

As far as the water utility Companies are concerned in Zambia, a developing Country, Sulfates,
nitrates and phosphates and heavy metals are expensive to remove from water. The expensive
techniques available for the removal of Sulfates or heavy metals from wastewater or drinking
water cannot be afforded by Our Zambian Utility Companies. To cab this problem of high levels
of Sulfates in the drinking water, this research focuses on laying down the method of removing
Sulfates from waste water and drinking water using readily available natural clay soil by the
simple surface phenomenon of adsorption.
 1.4 Objectives
The increase in the number of Mine industries and their poor disposal practices of wastewaters,
and also wastes such as detergents, Soap, and Pharmaceuticals by the public makes
contamination of freshwater very likely. Since Zambia is a developing Country which can hardly
afford to remove wastes such as Sulfates from wastewaters by the available techniques, this
research focuses on the removal of Sulfates from waste water containing Sulfates using the
readily available natural clay soil in Zambia. This is achieved by using Synthetic water Samples
in 50mL Standard glass Volumetric flasks. The objectives of this research are;
1 To determine how much Sulfates can be removed from the Standard Synthetic water
Sample using natural clay soil
2 To compare the reliability of the results of this method of using Natural clay to the
results of other techniques
3 To determine how much Clay should be used per given volume of synthetic water
sample of Sulfates.

1.5 Research Questions

The questions to be answered were:
5.1 Does Clay remove any significant amount of Sulfates from water?
5.2 How much Sulfates are removed by Clay soil,
 Chapter Two
2.1 Background and Literature review
The presence of Sulfates in the Water including air, soil and plants is becoming an increasing
health and environmental concern owing to the wide range of anthropogenic sources of Sulfates
polluting the environment with growing industrialization and extensive use of chemicals.
Wastewater effluent streams from many industries display wide varying Sulfates concentrations.
From tap water studies with human volunteers indicate a laxative effect at concentrations of
1000–1200 mg/liter. The presence of sulfate in drinking-water can also result in a noticeable
taste; the lowest taste threshold concentration for sulfate is approximately 250mg/Liter as the
sodium salt. Sulfate may also contribute to the corrosion of distribution systems [1]. Some other
concerns regarding the health effects from sulfate in drinking water have been raised because of
reports that diarrhea may be associated with water that contains high levels of sulfate. In the
livestock production industry, there is a concern that high levels of sulfates in water can
adversely affect productivity [2].

In the bodies of humans and other animals, Sulfates are very necessary constituents. In Humans,
Serum sulfates levels range from 24 to 36.5 mg/L. Sulfate is involved in many biochemical
activities including the production of chondroitin sulfate and Sulfation of exogenous chemicals.
However, reports to cause various health problems with high concentration of Sulfate in drinking
water have been given. Infants experiencing gastroenteritis with diarrhea and dehydration upon
ingesting water that had high levels of sulfate (650–1150 mg/L) [3]. A conclusion though, was
made that they is no scientific evidence to support a regulation creating a Maximum
Contaminant Level (MCL) for sulfate in drinking water [4]

Sulfates causes Eutrophication. Eutrophication is basically the rapid growth of crops in the rivers
as the result of high concentration of nutrients. The available nutrients are the constituents of
fertilizers that run off into the rivers from nearby farms, which includes Nitrates, Phosphorus and
Sulfates etc. Eutrophication by Sulfates is indirectly caused in the freshwaters. Sulfates are
reduced leading to mineralization of organic matter in marine sedments. Sulfate reduction,
however leads to nutrient kinetics indirectly. Sulfide produced by sulfate reduction interferes
with Iron- phosphate binding in soils and sediments due to the formation of iron sulfides. In this
way, phosphate is released both in marine and in freshwater sediments. The Literature shows that
the amount of phosphates on the availabiltiy of sulfates. [5]
Sulfates exist as free ions or complexes with heavy Metals and/or other Inorganic Compounds.
The presence of sulfates in water of Kafue, Kafubu and Zambezi rivers in Zambia is mainly from
Mines. In the Mines, when Copper ore is leached using an acid the residues are called Tailings.
When Sulfate ores are mixed with water and a surfactant creating a slurry. The slurry, when
agitated causes the copper sulfides minerals to float at which point they are skimmed off the
surface dried, the residues are also called Tailings. These Tailings are generally made up of very
fine host rocks (i.e. gangue) and nonmetallic minerals separated from the values during
beneficiation (http://www.greenspec.co.uk/building-design/copper-production-environmental-
impact/). They contains a lot of compounds and among are sulfates and these are discharged into
the Streams and later contaminates the fresh water in Kafue River, Kafubu River and other
Rivers in Zambia. Acid Mine Drainage (AMD) is the most significant environmental pollution
problem associated with mining industry. Caused by the occurrence of pyrite (FeS2) and sulfides
minerals with the rock coal seams when they are exposed to the air and mine water, then
oxidation and hydrolysis resulting in the generation of acid mine drainage contributing large
amounts of sulfates in fresh water [6] . Another sources of Sulfate is Agriculture by use of
synthetic fertilizers for the crops in people’s farms. These fertilizers contains sulfates which run
off into the rivers such as Kafue and Zambezi Rivers. Pharmaceuticals are yet another
contributors to high concentrations of sulfates in rivers. [7]

The methods that are commonly used to remove Sulfates from wastewater are Nano-filtration,
Reverse Osmosis, ion exchange (IX) Electro-dialysis, and the Cost Effective Sulfates Removal
(CESR) process currently considered to be able to address the shortcoming of other technologies/
methods. [8]

The method deployed in this research is very simple and cheap. It uses natural clay soil,
Kaolinite to be specific, which is readily available in Zambia. Natural clay soil (as Absorbent) is
used to absorb Sulfate (as absorbate) from waste water by a phenomenon called Absorption.
Adsorption is an attractive surface phenomenon, a physic-chemical separation process whereby
the adsorbate material is transferred from the bulk liquid phase to the adsorbent solid surface. [9]
The amount of Sulfates is measured by the turbidimetric method basing upon the fact that barium
sulfates tends to precipitate in a colloidal form of uniform size and this tendency is enhanced in
presence of a sodium chloride, hydrochloric acid and glycerol. [10] Turbidimetric is the process
of measuring the loss of intensity of transmitted light due to the scattering effect of particles
suspended in it. [11]
Kaolinite Chemistry
The chemical Formula of kaolinite can be written in terms of oxides as Al2O3.2SiO2.2h2O. The
chemical analysis indicates that various ions may substitute in the structure, for example Al3+ for
SI4+ in the silica tetrahedral layer, and Mg2+ or Fe2+ for Al3+ in the alumina octahedral layer.
Kaolinite has a low cation exchange capacity of about 5 meq/100g compared with other 2:1 type
clay minerals such as montmorillonite (100meq/100g). The anion exchange capacity of kaolinite
on the other hand is higher than its cation exchange capacity, and may be attributed to the
replaceable (OH-) ions of the exposed alumina octahedral layer. [12]

Figure 2.1.1

This research is focusing on the removal of Sulfates from contaminated water using natural clay
soil. Contaminated water usually those eluted from manufacture and mining industries. However,
the wastewater used in this case is the synthetic water sample since the main objective of this
research is to find out how much Sulfates can be removed from water contaminated with Sulfates
using natural clay soil. The next chapter outlines the Methods employed to achieve this
objective.
Chapter Three
Methodology:
3.1 Materials required for the preparation of Standard sample.

Apparatus Required

UV-Visible Spectrometer, Sample Tubes, Standard flask, Beaker, spatula, Measuring Cylinder,
Wash Bottle, Tissue Paper.

Chemicals Required

Magnesium Chloride, MgCl2.6H2O, Sodium acetate, CHCOONa.3H2O, Potassium nitrate,

KNO3, and Acetic Acid, CH3COOH (99%), Barium Chloride, BaCl2 (20 – 30 mesh crystals),
anhydrous Sodium Sulfate, Na2SO4, Distilled water, H2O.

3.2 Preparation of Standard samples of sulfates (SO42-):

Standard stock sulfate solution

0.1479 g anhydrous sodium sulfates was accurately weighed and dissolved it in distilled water.
Using a funnel, the dissolved anhydrous sodium sulfate was transferred into a 1000 ml standard
measuring flask. The volume was made up to 1000 ml using distilled water. Technically, 1 ml
will equal to 100 µg of SO42-.
Sodium Sulfate (Na2SO4) = 0.1479g/1000ml
Na2 – 22.99g (2), S – 32.06g, O4 – 16.00g (4) => Molecular mass of Na2SO4 = 142.04g
1.479gNa2SO4/142.04gNa2SO4 = 0.01041255984 Moles of Na2SO4
=> 0.001041255984 Moles of SO4 2- X 96.06g SO42-/ 1 Mole = 0.100023049823g SO42-
Therefore, 0.1000g SO42- from 0.1479 of Na2SO4 and in 1000ml it gives;
0.0001g/ml X 1000mg/1g = 0.100 mg/ml
Therefore, 1.0 ml equals to 0.10 mg of SO42- also equal to 100 µg

A Buffer Solution

30.0162g of magnesium Chloride, MgCl2.6H2O, 5.0052g of Sodium acetate,

CH3COONa.3H2O, 1.0012g of Potassium nitrate, KNO3 and 20mL of acetic acid, CH3COOH
(99%) were dissolved in 500mL and made up to 1000mL
3.3 Preparation of Blank and 4 Standard samples for Testing

Six 100 ml glass stoppered Standard flasks are used and in the first four, the volumes of 5 ml, 10
ml, 15 ml and 20 ml of standard sulfate solution were added respectively. The firth standard flask
was filled with distilled water as a blank sample. In all the five standard flasks 20 ml of buffer
solution was added and made up to the volume of 100 ml mark using distilled water.

UV- spectrometer and Spectra Manager – software.

The UV - visible Spectrometer instrument is used in the determination of Sulfate concentration

of Standards as well as Samples and this was done by Turbidimetric method. The absorbance of
the five standards were measured using UV- visible Spectrometer at 420nm. This Spectrometer
is connected to the Computer loaded with a Spectra manager Software. The Spectra manger is a
software which receives input from UV – visible spectrometer; it helps draw the Graph for
Standards Sulfates that enables the determination of the concentrations of Sulfates.

3.3.1 Standard Sample Testing

The five prepared Standard solutions were inserted in the machine and the information was
collected for the calibration of the curve/graph of the Standard Sulfate Solutions. A spoonful of
Barium chloride (BaCl2) was added and stirred for 60 ±2 Minutes immediately after which a cell
was inserted into the Spectrometer to measure the turbidity.

The Samples were run in the Spectrometer starting from the blank sample via sample 1 to the last
sample 4. The linear curve was obtained and the samples were ran through.
3.4 Materials required for preparation of Sample. Kaolinite (Clay Soil),

Apparatuses: Beakers, spatula, and Standard flasks.

3.4.1 Preparation of Sample

To prepare the sample solution to use to dissolve Kaolinite clay soil, 500ml of the stock standard
solution was put into a 1000mL flask and made up to the 1000mL mark using distilled water.
The Concentration of Sulfates, SO42- in this 1000mL Flask is 25mg/L. Three replicates of this
were made with different known concentrations as follows;
Sample A
0.07395g of Sodium Sulfate (Na2SO4) was weighed using an Analytical balance (From School of
Mines and mineral sciences). It was dissolved using distilled water and poured in a 100ml
standard volumetric flask and made up to 100 mark using distilled water.
Sample B
0.1849g of Sodium Sulfate (Na2SO4) was weighed. It was dissolved using distilled water and
poured into a 100ml standard volumetric flask and made up to 100 mark using distilled water.
Sample C
0.2958g of Sodium Sulfate (Na2SO4) was weighed and was dissolved using distilled water.
Using a funnel it was poured into a 100ml standard volumetric flask and made up to 100 mark
using distilled water.
50ml volume of each of the three Samples, Sample A, Sample B and Sample C prepared were
put in a separate beakers labeled Beaker A, Beaker B and Beaker C respectively. Then 5g of clay
soil was added to the all the beaker and mixed thoroughly. The Mixture were allowed to stay for
5 days while checking and stir all the time.
Four Sulfate solutions were made with different known concentrations. The concentrations were
twice each the first four Standards earlier prepared. Four separate heaps of 10 grams of Kaolinite
were prepared. The same amount of kaolinite was mixed with each of the sulfate solutions and
stirred thoroughly, and stored for at least 5 days.

3.4.2 Sample Testing

For the synthetic Samples, after mixed with Kaolinite (Clay) for 5 days, the Liquids of all
Samples were decanted. Three Water Samples after decanting, where too had a pinch of Barium
chloride (BaCl2) added to it and put in a cell and inserted into the Spectrometer. The sulfate
concentrations were determined at 420nm using the UV- spectrometer. This procedure was done
in three sets to ensure that satisfying data was collected.
Chapter Four
4.1 Data Analysis
Out of 1000mL prepared Standard solution of Sulfates, 50mL of was put in a beaker and 50mL
of distilled water was added making up of a solution of up to 100mL. Since in 1000mL they is
100mg of Sulfates, in 50mL they is 5mg. When 50mL of distilled water is added giving the final
volume of 100mL, the concentration of Sulfates is 25mg/L. To this volume (100mL of Sulfate
solution) 5g of Clay was added and stirred and made to stay for 5 days (from Thursday, 17/10/19
to Tuesday, 22/10/19).
The second stirring was made on Monday and on Tuesday the solution was decanted. To the
decant, 20mL of Buffer solution was added, stirred and a spoonful of Barium Chloride was
added and stirred for 60 minutes after which immediately was put in a cuvette and inserted in a
machine. The new concentration measured was 90.8mg/L at 420nm wavelength.
Today, Tuesday 22/10/2019. 150mL of Standard Sulfate solution was put in an Erlenmeyer flask
and 150mL of distilled water was added to make up to 300mL volume. Theoretically the
concentration of Sulfates in this volume is 25mg/L (since 100mg is in 1000mL). But when
100ml from the prepared 300mL was measured and 20mL buffer solution was added. A spoonful
of barium Chloride added and stirred for 60 minutes. Then it was put in a cell and inserted in the
machine to measure the concentration, the measured concentration was 39.3 mg/L, 14.3mg/L
more than the calculated concentration. Nevertheless, 125mL of the prepared 300mL solution
was put in a beaker and 5.0027g of Clay added and stirred. It will be made to stay for 6 days. On
Monday the concentration will be measured to check if the concentration will reduce as expected
or not.
4.2 Results

Samples Concentration Concentration Duration pH pH

Before After readings readings
Before After
Sample A

Sample B

Sample C
5 References

[1] M. J. Fawell and M. R. Mascarenhas, "Sulfate in Drinking-water," World Health Organization, 2004.

[2] A. DARBI, T. VIRARAGHAVAN, Y.-C. JIN, L. BRAUL and D. CORKAL, "Sulfate Removal from Water,"
Article in Water Quality Research Journal of Canada, pp. 169-182, 2003.

[3] C. L, R. H and G. JW, "Infantile gastroenteritis due to water with high sulfate content.," Can Med
Assoc J. , vol. III, pp. 102-104, 1968.

[4] M. J. Fawell and M. R. Mascarenhas, "Sulfate in Drinking-water. Background document for

development of WHO Guidelines for Drinking-water Quality.," World Health Organization, United
Kingdom, 2004.

[5] L. L. P. M, T. H. B. M and J. G. M. ROELOFS, "Sulfate-Induced Eutrophication and Phytotoxicity in

Freshwater Wetlands," Research Group Environmental Biology, Department ofEcology, University
of Nijmegen, Toernooiveld 1, 6525, ED Nijmegen, the Netherlands, 1998.

[6] G. Udayabhanu, B. Prasad and Sangita, "Studies on environmental impact of acid mine drainage
generation and its treatment: An appraisal," Indian Journal of Environmental Protection, no. 11,
pp. 954-967, 2010.

[7] S. M, RAO and S. A., "MECHANISM OF SULFATE ADSORPTION BY KAOLINITE," MECHANISM OF

SULFATE ADSORPTION BY KAOLINITE, pp. 414-418, 1984.

[8] A. Tiruneh, T. Debessai, G. Bwembya and S. Nkambule, "Combined Clay Adsorption-Coagulation

Process for the Removal of Some Heavy Metals from Water and Wastewater," American Journal of
Environmental Engineering, vol. 8, pp. 25-35, 2018.

[9] A. T. Tiruneh1, T. Y. Debessai2, G. C. Bwembya2 and S. J. Nkambule1, "Combined Clay Adsorption-

Coagulation Process for the Removal of Some Heavy Metals from Water and Wastewater,"
American Journal of Environmental Engineering, vol. 2, pp. 8(2): 25-35, 2018.

[10] BUREAU OF INDIAN STANDARDS. , "METHODS OF SAMPLING AND TEST (PHYSICAL AND CHEMICAL)
FOR WATER AND WASTEWATER PART 24 SULPHATES," IS : 3026 (Part 24 )-1986, p. 8, January
1998.

[11] M. C. Haven, G. A. Tetrault and J. R. Schenken, Laboratory Instrumentation, Canada, 1995, pp. 123-
132.

[12] V. Gupta, "SURFACE CHARGE FEATURES OF KAOLINITE PARTICLES AND THEIR INTERACTIONS,"
Vishal Gupta, 2010.