ABSTRACT
Activated tamarind kernel powderwas prepared from tamarind seed(Tamarindus indica);and
utilized for the removal of Acid Red 1, Reactive Orange 20 and Reactive blue 29 dyes from their
aqueous solutions. The powder was activated using 4M nitric acid (HNO3). The effect of various
parameters which include; pH, adsorbent dosage, ion concentration, and contact time were
studied to identify the adsorption capacity of the activated tamarind kernel powder under the
above conditions. The percentage of dye adsorbed is seen to be dependent on these factors. The
result obtained indicated that the adsorption of Acid Red 1 (AR1), Reactive Orange 20 (RO20)
and Reactive Blue 29 (RB29) decreased with increase in initial concentration but increased with
increase in temperature. At equilibrium, all three dyes showed highest dye uptake at initial dye
concentration of 20 mg/l, pH 2, adsorbent dose of 1.0 g, and at a contact time range of 80-100
min. The Langmuir, Freundlich, Temkin and Dubinin Radushkevichisotherm models measured
at a temperature range of 298-328K are fitted into the graphs. The Temkin isotherm model is
best-fitted into the experimental data with R2
values ranging between 0.913-0.987 for Acid Red
1, 0.865-0.969 for Reactive Orange 20 and 0.942-0.992 for Reactive Blue 29. The next in line for
best fitting is the Langmuir isotherm with R2
values ranging between 0.859-0.995 for Acid Red 1
dye, 0.825-0.974 for Reactive Orange 20 and 0.971-0.989 for Reactive Blue 29. This is followed
by Dubinin Radushkevich isotherm with R2
values ranging between 0.931-0.974 for Acid Red 1,
0.923-0.989 for Reactive Orange 20 and 0.789-0.923 for Reactive Blue 29. Lastly is the
Freundlich isotherm with R2
values ranging between 0.803-0.931 for Acid Red 1, 0.856-0.964
for Reactive Orange 20 and 0.982-0.995 for Reactive Blue 29. The pseudo-first order and
pseudo-second order kinetic models were also fitted into the graphs, but pseudo-second order
was best fitted into the experimental data. The thermodynamic parameters such as enthalpy,
entropy, and free energy which were determined using the Van‘t Hoff equations were found to
vii
provide the clues necessary to predict the nature of the adsorption process. The values of the
activation energy (EA) obtained indicated that the adsorption of AR1, RO20 and RB29 on
activated tamarind kernel powder (ATKP) is a physical process.The negative free energy (ΔG)
indicatedthat the adsorption process is feasible and spontaneous, the negative enthalpy (ΔH)
indicatedthat the reaction is exothermic in nature and the negative entropy (ΔS) indicated that
there is decreased randomness at the solid/solution interphase during the adsorption process. The
chemical functional groups of the ATKP adsorbent were studied by Fourier Transform Infrared
(FTIR) spectroscopy which helped in the identification of possible adsorption sites on the
adsorbent surface. Characterization of the activated tamarind kernel powder which was carried
out using standard methods, showed that the values of the parameters of interest such as moisture
and dry matter content, ash content, pH and bulk density; fall within acceptable range. Therefore,
activated tamarind kernel powder has proven to be a very good adsorbent for the removal of acid
dyes and reactive dyes.
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Abstract vi
Table of Contents viii
List of Figures xiv
List of Tables xix
List of Appendices xxi
List of Plates xxiii
Abbreviations xxiv
CHAPTER ONE INTRODUCTION
1.1 Background of Study 1
1.2 Statement of Research Problem 3
ix
1.3 Justification for the Research 3
1.4 Aim and Objectives 4
CHAPTER TWO LITERATURE REVIEW 5
2.1 Dyes 5
2.1.1 Acid Dyes 5
2.1.2 Reactive Dyes 6
2.1.2.1 C.I. Reactive Blue 29 6
2.1.2.2 C.I. Reactive Orange 20 7
2.2 Tamarind 8
2.2.1 Taxonomy 9
2.2.2 Botanical Description 10
2.2.3 Common/Vernacular Names 10
2.2.4 Fruits and Seeds 10
2.2.5 Origin and Geographical Distribution 11
2.3 Polymers 11
2.4 Adsorption 13
2.4.1 Types of Adsorption 14
x
2.4.1.1 Chemisorption 14
2.4.1.2 Physisorption 14
2.4.3 Extent of Adsorption 15
2.4.4 Adsorption Rate 16
2.4.4 Adsorption Isotherms 16
2.4.4.1 Langmuir Isotherm 17
2.4.4.2 Freundlich Isotherm 18
2.4.4.3 Temkin Isotherm 20
2.4.4.4 Dubinin Radushkevich Isotherm 20
2.4.5 Adsorption Thermodynamics 21
2.4.5.1 Van‘t Hoff Plot 21
2.4.5.2 Development of Van‘t Hoff Plot 22
2.4.6 Adsorption Kinetics 23
2.4.6.1 Pseudo-First Order Kinetics 23
2.4.6.2 Pseudo-Second Order Kinetics 23
2.5 Tamarind kernel Polysaccharide 24
2.5.1 Industrial Utilization of Tamarind Kernel Powder 25
2.5.1.1 Pharmaceutical Applications of TKP 25
xi
2.5.2 Tamarind Kernel Powder as Composite Material 26
2.5.2.1 Hydroxyapatite (Hap)/Tamarind Kernel Powder (TKP) Composite 26
2.5.2.2 Fourier Transform Infrared Spectroscopy of TKP/HAp Nano Composites 26
2.5.3. Tamarind Kernel Powder in Diary Waste water Treatment 27
CHAPTER THREE MATERIALS AND METHODS29
3.1 Materials 29
3.1.1 Sample Collection, Identification and Treatment 29
3.1.2 Preparation of 0.1M HCl 29
3.1.3 Preparation of 0.1 M NaOH 29
3.1.4 Preparation of 4 M HNO3 29
3.1.5 Adsorbate Preparation 30
3.2 Methods 30
3.2.1 Preparation of Adsorbent 30
3.2.2 Characterization of ATKP 30
3.2.2.1Moisture and Dry Matter Content 30
3.2.2.2Ash Content 31
3.2.2.3 pH measurement 31
3.2.2.4 Bulk Density 32
xii
3.2.3FTIR Analysis 32
3.2.4 Adsorption Experiment 33
3.2.4.1 Effect of initial Dye Concentration 33
3.2.4.2 Effect of Adsorbent Dose 34
3.2.4.3 Effect of pH 34
3.2.4.4 Effect of Contact Time 34
3.2.4.5 Effect of Temperature 34
3.2.4.6 Adsorption Isotherms 35
3.2.4.7 Adsorption Kinetics 35
3.2.4.8 Adsorption Thermodynamics 35
CHAPTER FOUR RESULTS 37
4.1 Characterization of ATKP 37
4.2 FTIR Analysis of ATKP 37
4.3 Adsorption Studies 37
4.4 Adsorption Isotherms 37
4.4.1 Langmuir Isotherms 37
4.4.2 Freundlich Isotherms 67
xiii
4.4.3 Temkin Isotherms 67
4.4.4 Dubinin-Radushkevich Isotherms 67
4.5 Adsorption Kinetics 67
4.6 Adsorption Thermodynamics 67
CHAPTER FIVE DISCUSSION 122
5.1 Characterization of ATKP 122
5.1.1 Moisture and Dry Matter Content 122
5.1.2 Bulk Density 122
5.1.3 Ash Content of ATKP 123
5.1.4 pH of ATKP 123
5.2 FTIR Analysis of ATKP 123
5.3 Adsorption Studies 125
5.3.1 Effect of pH 125
5.3.2 Effect of Adsorbent Dose 126
5.3.3 Effect of Contact Time 126
5.3.4 Effect of initial Concentration 127
5.3.5 Adsorption Isotherm Modelling 128
xiv
5.3.5.1Langmuir Isotherm 128
5.3.5.2 Freundlich Isotherm 130
5.3.5.3 Temkin Isotherm 132
5.3.5.4 Dubinin Radushkevich 134
5.4 Adsorption Kinetics 136
5.5 Adsorption Thermodynamics 138
CHAPTER SIX SUMMARY, CONCLUSION AND RECOMMENDATIONS 139
6.1 Summary and Conclusion 139
6.2 Recommendations 140
6.3 Contributions to Knowledge 141
REFERENCES 142
APPENDICES
CHAPTER ONE
INTRODUCTION
1.1 Background of Study
Environmental pollution control is said to be amatter of utmost concern in many countries.
However, air and water pollution constitute the major environmental pollution in several
countries. Consequently, open burning leads to air pollution, while industrial effluent and
domestic sewage leads to water pollution. Water pollution results to bad effects on public
water supplies which can cause health problem, while air pollution can cause lung diseases,
burning eyes, cough, and chest tightness. The environmental issues surrounding the presence
of colour in effluent is a continuous problem for dye stuff manufacturers, dyers, finishers, and
water companies (Kesari etal., 2011).
The contaminants such as dyes, heavy metal, cyanide, toxic organics, nitrogen, phosphorus,
phenols, suspended solids, colour, and turbidity from industries and untreated sewage sludge
from domestics, are becoming of great concern to the environmental and public health.
Therefore, the treatment of these pollutants is very important (Cheremisinoff, 1993).
Residual dyes from different sources (e.g., textile industries, paper and pulp industries, dye
and dye intermediates industries, pharmaceutical industries, tannery, and Kraft bleaching
industries and others) are considered a wide variety of organic pollutants introduced into the
natural water resources or wastewater treatment systems. One of the main sources with severe
pollution problems worldwide is the textile industry and its dye-containing wastewaters (i.e.
10,000 different textile dyes with an estimated annual production of 7.105 metric tonnes are
commercially available worldwide; 30% of these dyes are used in excess of 1,000 tonnes per
annum, and 90% of the textile products are used at the level of 100 tonnes per annum or less)
(Baban et al., 2010; Robinson et al., 2001; Soloman et al., 2009). About 10-25% of textile
dyes are lost during the dyeing process, and 2-20% is directly discharged as aqueous effluents
2
in different environmental components. In particular, the discharge of dye-containing
effluents into the water environment is undesirable, not only because of their colour, but also
because many of the dyes released and their breakdown products are toxic, carcinogenic or
mutagenic to life forms mainly because of carcinogens, such as benzidine, naphthalene and
other aromatic compounds (Suteu et al., 2009; Zaharia et al., 2009). Without adequate
treatment these dyes can remain in the environment for a long period of time. For instance,
the half-life of hydrolysed Reactive Blue 19 is about 46 years at pH 7 and 298 K (Haoet al.,
2000).
In addition to the aforementioned problems, the textile industry consumes large amounts of
potable and industrial water as processing water (90-94%) and a relatively low percentage as
cooling water (6-10%) in comparison with the chemical industry where only 20% is used as
process water and the rest for cooling. The recycling of treated wastewater has been
recommended due to the high levels of contamination in dyeing and finishing processes (i.e.
dyes and their breakdown products, pigments, dyeintermediates, auxiliary chemicals and
heavy metals, and others(Bertea and Bertea, 2008; Bisschops and Spanjers, 2003; Correia et
al., 1994; Orhon et al., 2001).
Synthetic dyes have been increasing in textile industries for dyeing natural and synthetic
fibres. Discharge of dye- bearing waste-water makes an adverse effect on aquatic
environment because the dyes give water undesirable colour (Ibrahim et al., 2010) and reduce
light penetration and photosynthesis (Al-Degs et al., 2004; Wang et al., 2005; Oei et al.,
2009). Conventional methods used to treat coloured effluents are oxidation, coagulation and
flocculation, biological treatment, membrane filtration. However, the single conventional
treatment is unable to remove certain forms of colour, particularly those arising from reactive
dyes as a result of their high solubility and low biodegradability (Vijayaraghavan et al.,
2009).
3
1.2 Statement of Research Problem
One of the major problems concerning textile and leather wastewaters is coloured effluent
(Ramakrishna, et al; 1997). This wastewater contains a variety of organic compounds and
toxic substances, which are harmful to fish and other aquatic organisms. Dyes even in low
concentrations affect the aquatic life and food web. Since many organic dyes are harmful to
human beings, the removal of colour from process or waste effluents becomes
environmentally important. Due to the large degree of organics present in these molecules
and the stability of modern dyes, conventional physicochemical and biological treatment
methods are ineffective for their removal (Mckay, 1995).
1.3 Justification for the Research
Activated carbon is a widely used adsorbent due to its high adsorption capacity, high surface
area, microporous structure, and high degree of surface reactivity, but there are some
problems associated with its use,it is expensive and regeneration results in a 10–15% loss of
adsorbent and its uptake capacity and therefore this adds to the operational costs. This led to a
search for cheaper, easily obtainable materials for the adsorption of dye from industrial
effluent (Waranusantigulet al., 2003). As a result, the use of natural waste products and plants
has increased considerably during the past years for pollution control applications (Kumar et
al., 2009).
Tamarind Kernel is a biological waste material which is readily available and relatively
cheap. It can be collected and powdered. (Shanthi and Mahalakshmi,2012).It has excellent
potential for the removal of dye from coloured effluent (Patel and Vashi, 2010).TKP has been
used to remove dyes from the binary mixture of their aqueous solution (Shanthi and
Mahalakshmi,2012).It has also found excellent application in the reduction of Chemical
oxygen demand (COD), Total dissolved solids; Sulphates and Turbidity from diary waste
water (Shobaet al., 2015).
4
1.4 Aim and Objectives
The aim of this research is to characterize and utilize Activated Tamarind Kernel Powder
(ATKP) in the treatment of Industrial waste water.
This aim will be achieved by the following objectives:
i. To isolate, carbonize and activate the tamarind kernel powder
ii. To determine some physicochemical parameters which include pH, contact time,
adsorbent dose and initial concentration of the ATKP adsorbent
iii. To run the FTIR Spectra of the activated ATKP adsorbent before and after treatment
with Acid Red 1, Reactive Orange 20 and Reactive Blue 29 (AR1, RO20 and RB29)
in order to identify the functional groups responsible for the adsorption of each dye
molecule unto the ATKP surface
iv. To analyse the effect of Initial concentration, Initial pH, Contact time, Adsorbent dose
and operating Temperature in order to determine the optimum conditions for
maximum adsorption of the dyes (AR1, RO20 and RB29) from their aqueous
solutions
v. To examine the adsorption efficiency of ATKP for AR1, RO20 and RB29 by
analysing the adsorption isotherms (Langmuir, Freundlich, Temkin and DubininRadushkevich)
vi. To examine the rate of adsorption by studying the adsorption Kinetics (Lagagren
Pseudo-First order and Pseudo-Second order)
vii. To examine the spontaneity of adsorption of AR1, RO20 and RB29 on ATKP through
the determination of the thermodynamics parameters (Standard Gibbs free energy,
Activation Energy, Enthalpy and Entropy)
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