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UNIVERSITI PUTRA MALAYSIA

ISOTHERM AND KINETICS OF REACTIVE DYE ADSORPTION ON

PALM KERNEL SHELL-BASED ACTIVATED CARBON

MOHSEN NOUROUZI MOBAREKEH

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ISOTHERM AND KINETICS OF REACTIVE DYE ADSORPTION ON PALM KERNEL SHELL-BASED ACTIVATED CARBON

By

MOHSEN NOUROUZI MOBAREKEH

Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia, in Fulfilment of the Requirements for the Degree of Master of Science

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Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment of the requirement for the degree of Master of Science.

ISOTHERM AND KINETICS OF REACTIVE DYE ADSORPTION ON PALM KERNEL SHELL- BASED ACTIVATED CARBON

By

MOHSEN NOUROUZI MOBAREKEH DECEMBER 2007

Chairman: Chuah Teong Guan, PhD Faculty: Engineering

The adsorptions of two reactive dyes, Reactive Black 5 and Reactive Red E onto Palm Kernel Shell-based activated carbon (granule form) and commercial grade coal-based activated carbons (powder form) were studied. The experiment was carried out to investigate the effect of the presence of more than one type dye in solution on equilibrium and kinetic of adsorption. Equilibrium isotherm models were applied to describe the adsorption capacities of both single and binary systems. All batch experiments were carried out at a constant temperature of 28°C (+2°C) using an incubator shaker that was operated at 150 rpm.

The results showed that adsorption of reactive dyes onto commercial coal-AC from single system can be successfully described by Langmuir model. The adsorptions onto Palm Kernel Shell-AC in single and binary systems can be successfully described by Freundlich and the Redlich-Peterson models and by Modified Extended Freundlich model, respectively. Experimental data showed that competitive

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iii adsorption for active sites on the carbon surface reduces overall uptake capacity of the reactive dyes.

The rate of adsorptions of two reactive dyes, Reactive Black 5 and Reactive Red E onto Palm Kernel Shell-AC were studied. The sorption kinetics was well described by pseudo-second-order kinetic model in single system. In addition, the experiment was carried out to investigate three models: film resistance model, film-surface and film-pore diffusion models. The results showed that the external coefficients of mass transfer, Kf, decreased with increasing of initial adsorbate concentration. Variations

of Kf values, indicated that adsorption was controlled by both external and

intraparticle diffusion. Furthermore, simulation results showed that the rate of the kinetic process was controlled by two resistance models. It was found that the adsorption process was better described by film-surface diffusion model.

Finally, the Chemical Oxygen Demand (COD) of the treated reactive dyes solutions from single and binary systems showed that a minimum of 4g/L dosage of PKS was needed to reduce the COD to acceptable level according to the United State Water Quality Guidelines and Pollutant Fact Sheets guidelines.

From the work, it was clearly shown that PKS-AC had good adsorption capacity on reactive dye. This study provides information on adsorption mechanism of binary reactive dye system which is useful in adsorption column design.

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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Master Sains.

KAJIAN ISOTERMA DAN KINETIK TERHADAP PENJERAPAN PEWARNA REAKTIF MENGGUNAKAN CENGKERANG ISIRUNG KELAPA SAWIT

BERASASKAN KARBON AKTIF. Oleh

MOHSEN NOUROUZI MOBAREKEH DESEMBER 2007

Pengerusi: Chuah Teong Guan,PhD Fakulti: Kejuruteraan

Penjerapan oleh dua pewarna reaktif iaitu Reaktif Hitam 5 dan Reaktif Merah E menggunakan cengkerang isirung kelapa sawit berasaskan karbon aktif dalam bentuk granul dan arang batu tahap komersial berasaskan karbon aktif dalam bentuk serbuk, telah dikaji. Ujikaji telah dijalankan untuk menentukan kesan kewujudan lebih daripada dua pewarna di dalam larutan terhadap keseimbangan dan kinetik penjerapan. Model keseimbangan isoterma telah digunakan untuk menggambarkan kapasiti penjerapan dalam sistem tunggal dan sistem dedua. Kesemua ujikaji kelompok ini dijalankan pada suhu tetap iaitu 28°C (+2°C) dengan menggunakan penggoncang eraman yang beroperasi pada 150 rpm.

Keputusan ujikaji menunjukkan bahawa penjerapan pewarna reaktif ke atas arang batu komersial-AC untuk sistem tunggal boleh dijelaskan dengan menggunakan model Langmuir. Penjerapan ke atas cengkerang isirung kelapa sawit dalam sistem tunggal dan sistem dedua boleh dijelaskan dengan menggunakan model Freundlich dan Redlich-Peterson dan juga model Freundlich yang dipanjangkan dan teruhah suai. Data ujikaji

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v menunjukkan bahawa penjerapan persaingan untuk tapak aktif pada permukaan karbon mengakibatkan penurunan keseluruhan kapasiti pewarna reaktif yang dijerap.

Kadar penjerapan oleh dua pewarna reaktif iaitu Reaktif Hitam 5 dan Reaktif Merah E di atas cengkerang isirung kelapa sawit-AC dikaji. Kadar penjerapan dalam sistem tunggal adalah berpadanan dengan kinetik pseudo tertib kedua. Selain itu, ujikaji ini juga dijalankan untuk mengkaji 3 jenis model iaitu model rintangan lapisan, permukaan lapisan dan resapan liang lapisan. Keputusan menunjukkan bahawa pekali luaran untuk pemindahan jisim Kf menurun dengan meningkatnya kepekatan awal zat terjerap. Nilai Kf

yang berbeza-beza menunjukkan bahawa kadar penjerapan dipengaruhi oleh faktor resapan luaran dan intrazarah. Selain itu, simulasi menunjukkan bahawa proses kinetik di pengaruhi oleh model ketahanan kedua. Proses penjerapan boleh ditafsirkan dengan lebih baik dengan menggunakan model resapan permukaan lapisan.

Pada akhir ujikaji, Keperluan Oksigen Kimia(COD) untuk larutan yang dirawat dari sistem tunggal dan sistem dedua menunjukkan bahawa sekurang-kurangnya 4 g/L dos PKS diperlukan untuk menurunkan bacaan COD kepada tahap yang dibenarkan oleh Piawaian Kualiti Air dan Piawaian Fakta Pencemaran, Amerika Syarikat.

Daripada keputusan yang diperolehi, jelas menunjukkan bahawa PKS-AC mempunyai kapasiti penjerapan yang baik ke atas pewarna reaktif. Ujikaji ini memberi maklumat tentang mekanisma penjerapan untuk sistem dedua pewarna reaktif yang berguna untuk rekabentuk turus penjerapan.

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ACKNOWLEDGEMENTS

Alhamdulillah, at last this thesis has finally completed. I wish to express my deepest appreciation to my supervisor Dr. Chuah Teong Guan and co-supervisors Dr. Thomas Choong Shean Yaw for their guidance, insightful comments and patient supervision of this work. I also owe a special debt of thanks to all technicians in the Department of Chemical and Environmental Engineering and my fellow colleagues for their helping hand. The helpful collaboration of KD Technology Sdn. Bhd. is highly appreciated. I would like to thank my beloved wife for his understanding and support during this study. I am also very grateful to my family and friends for their encouragement and sharing time throughout this journey.

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I certify that an Examination Committee has met on 17 December 2007 to conduct the final examination of Mohsen Nourouzi Mobarekeh on his Master of Science thesis entitled “Isotherm and Kinetics of Reactive Dye Adsorption on Palm Kernel Shell-Based Activated Carbon” in accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree) Regulations 1981. The Committee recommends that the student be awarded the degree Master of Science.

Members of the Examination Committee were as follows:

Azni Idris Professor

Faculty of Engineering Universiti Putra Malaysia (Chairman)

Dayang Radiah Awang Biak Lecturer

Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Suraya bt. Abdul Rashid Lecturer

Faculty of Engineering Universiti Putra Malaysia (Internal Examiner)

Ir.Abdul Wahab Mohammad Professor

Faculty of Engineering

Universiti Kebangsaan Malaysia (External Examiner)

___________________________________ HASANAH MOHD.GHAZALI, PhD Professor and Deputy Dean

School of Graduate Studies Universiti Putra Malaysia Date: 28 April 2008

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viii This thesis submitted to the Senate of Universiti Putra Malaysia and has been accepted as fulfilment of the requirement for the degree of Master of Science. The members of the Supervisory Committee are as follows:

Luqman Chuah Abdullah, PhD Associate Professor

Faculty of Engineering Universiti Putra Malaysia (Chairman)

Thomas Choong Shean Yaw, PhD Associate Professor

Faculty of Engineering Universiti Putra Malaysia (Member)

_______________________ AINI IDERIS, PhD

Professor and Dean

School of Graduate Studies Universiti Putra Malaysia Date: 8 May 2008

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DECLARATION

I declare that the thesis is my original work except for quotations and citations which have been duly acknowledged. I also declare that it has not been previously and is not concurrently submitted for any other degree at Universiti Putra Malaysia or at any other institution.

__________________________ MOHSEN NOUROUZI

MOBAREKEH Date: 20 April 2008

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TABLE OF CONTENTS Page ABSTRACT ii ABSTRAK iv ACKNOWLEDGEMENTS vi APPROVAL vii DECLARATION ix

LIST OF TABLES xiii

LIST OF FIGURES xv

LIST OF NOTATIONS / SYMBOLS xvii

CHAPTER

1 INTRODUCTION

1.1 Water Pollution as an Environmental Pollutions Problem 1.1 1.2 Textile Dyes Effluent 1.1 1.3 Problem Statement And Objectives Of The Study 1.3

1.4 Scope of Study 1.6

2 LITERATURE REVIEW

2.1 Reactive Dyes 2.1

2.2 Methods of Dyestuff Treatment 2.2 2.3 Application of Activated carbons 2.3 2.4 Raw Materials Used in Production of Activated Carbon 2.4 2.5 Characteristics of Activated Carbon 2.5 2.5.1 Total Surface area 2.7

2.5.2 Carbon Density 2.7

2.5.3 Particle Size Distribution (PSD) 2.7 2.5.4 Adsorption Capacity 2.8

2.6 Factors Effecting Adsorption Capacity 2.8 2.7 Factors Affecting Adsorption Rate 2.9 2.8 Removal of Organic Contaminant 2.10 2.9 Activated Carbon and Wastewater Treatment 2.11 2.10 Palm Kernel Shell-Based Activated Carbon 2.12

2.11 Theory Sorption 2.13 2.12 Isotherm of Adsorption 2.15 2.12.1 Henry’s Law 2.17 2.12.2 Langmuir Isotherm 2.18 2.12.3 Freundlich Isotherm 2.19 2.12.4 Redlich-Peterson Isotherm 2.20 2.13 Kinetics of Adsorption 2.20 2.13.1 Pseudo First-Order Lagergren Model 2.22 2.13.2 Pseudo Second-Order Kinetic Model 2.22 2.14 Mass Transfer Model 2.22 2.14.1 Single Resistance Models 2.24 2.14.2 Two Resistance Models 2.24 2.14.3 Three Resistance Model 2.25

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2.14.4 External Mass Transfer 2.25 2.14.5 Intraparticle Mass Transfer 2.26

A Surface Diffusion 2.26

B Pore Diffusion 2.26

2.15 Conclusion 2.26

3 MATERIALS AND METHODS

3.1 Materials 3.1 3.1.1 Adsorbents 3.1 3.1.2 Adsorbates 3.1 3.2 Equipment 3.2 3.3 Experimentations 3.3 3.3.1 Sampling Procedure 3.3 3.3.2 Batch EquilibriumsStudies 3.3 3.3.3 Initial pH 3.4

3.3.4 Batch Kinetic Studies 3.5

COD Experiment 3.7

3.4 Duplication and Control 3.8 4 MODELING 4.1 Isotherm 4.1.1 Langmuir Isotherm 4.1 4.1.2 Freundlich Isotherm 4.2 4.1.3 Redlich-Peterson Isotherm 4.2 4.2 Binary System 4.3

4.2.1 Extended Langmuir Equation 4.3 4.2.2 Extended Langmuir-Freundlich Equation 4.3 4.2.3 Modified Extended Freundlich Equation 4.4

4.3 Kinetic 4.5

4.3.1 Pseudo First-Order Lagergren Model 4.5 4.3.2 Pseudo Second-Order Kinetic Model 4.6 4.3.3 External Mass Transfer 4.7 4.3.4 Intraparticle Mass Transfer 4.8 A Film-Surface Diffusion 4.8 B Film-Pore Diffusion 4.10 5 RESULTS AND DISCUSSION

5.1 Introduction 5.1 5.2 Single System 5.2 5.2.1 Equilibrium Studies 5.2 A Langmuir Isotherm 5.2 B Freundlich Isotherm 5.4 C Redlich-Peterson Isotherm 5.5 D Error analysis 5.5 5.2.2 Kinetic Studies 5.9

A Effect of Initial Dye Concentrations 5.9 B Effect of Adsorbent Mass 5.11 C Pseudo First-Order Kinetics Model 5.12 D Pseudo Second-Order Kinetic Model 5.16

5.2.3 COD Measurement 5.20

5.2.4 Desorption phenomenon 5.21

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xii

5.3 Binary System 5.23

5.3.1 Equilibrium Studies 5.23 5.3.2 Comparison of Adsorption Kinetics 5.26 5.4 Intrapellet Mass Transfer Based-Adsorption Model 5.27

5.4.1 Single System 5.28

A Film-Surface Diffusion 5.28 B Film-Pore Diffusion 5.28

6 CONCLUSIONS AND SUGGESTIONS 6.1

REFERENCES R.1

APPENDICES A.1

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LIST OF TABLES

Table Page

Some materials used as activated carbon 1.3 Advantages and disadvantages of the current methods of

dye removal from textile wastewater

2.2 Different quality due to different raw materials used 2.5

Pore size in typical activated carbons 2.6 Summary of the classes of organic compounds adsorbed

by carbon

2.10 Characteristics of PKS – based activated carbon 3.1 Properties of RB 5 and RR E 3.2 Equipments used for experiment 3.2 Langmuir constants for the adsorption of RB 5 and RR E

onto commercial coal - based and PKS - based AC 5.2 Values of KL/αL as reported in the literature on

adsorption of RB 5 and RR E using different adsorbents

5.4 Freundlich constants for the adsorption of RB 5 and RR

E onto commercial coal - based and PKS - based activated carbon

5.4

Redlich – Peterson constants for the adsorption of RB 5 and RR E onto commercial coal - based and PKS - based AC

5.5

Comparisons of Sum of Square Errors (SSE) of isotherm models for adsorption of RB 5 and RR E onto PKS and coal - based AC (single system)

5.6

External Mass Transfer Coefficient for adsorption of RB 5 and RR E onto PKS- based AC (single system)

f

k 5.10

Effect of the initial dye concentration on the rate constant (k1) for the adsorption of R 5 and RR E onto PKS - based

AC

5.15

Effect of the adsorbent mass on the rate constant (k1) for

the adsorption of RB 5 and RR E onto PKS - based AC

5.16 Effect of the initial dye concentration on the rate constant

(k2) for the adsorption of RB 5 and RR E onto PKS -

based AC

5.17

Effect of the adsorbent mass on the rate constant (k2) for

the adsorption of RB 5 and RR E onto PKS - based AC 5.17 Amounts of COD for the adsorption of RB 5 and RR E at

concentration 800 mg/L onto PKS - based AC

5.21 Values of adsorption spectrum of RR E related to adsorption onto PKS-AC

5.22 Modified Extended Freundlich constants for the adsorption of RB 5 and RR E onto PKS - based AC (binary system)

5.24

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xiv 5.24

of RB 5 and RR E onto 5.27 n 5.28

pfor adsorption of RB 5 and RR E onto PKS 5.29

s for adsorption of RB 5and RR E onto PKS based-AC

5.29 Comparisons of SSE of isotherm models for adsorption

of RB 5 and RR E onto PKS- based AC (binary system) values of k , Df s for adsorption

PKS- based AC (single system)

Values of k , f D and s D , reported in the literature op

adsorption of different dyes using different adsorbents Values of D

based-AC

Comparison of SSE of surface diffusion and film-pore diffusion model

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LIST OF FIGURES

Figure Page

Flow chart of the work 1.6 Reaction between reactive dye and cellulosic surface 2.1 A: Oil Palm Plantations, B: Oil Palm Fruit Bunch, C: Palm

Kernel Shell, D: Carbonized Palm Kernel Shell, E: Activated Palm Carbon

2.13

The five types of pure-component gas-adsorption isotherms in the classification of Brunauer. Where is the adsorbed phase concentration;

e q o p p is the relative pressure. 2.16

Schematic representation of an adsorbent particle 2.23 Mass transfer in adsorption processes. (a) Batch or continues-flow tanks, (b) Fixed or fluidized beds, and (c) Intrapellet mass transfer. 1a: axial dispersion, 1b: radial dispersion, 2: interphase mass transfer, 3: intrapellet mass transfer, 3a: pore diffusion, 3b: surface diffusion, 4: adsorption

2.24

Flow chart for batch equilibrium studies 3.5 Flow chart for batch kinetic studies 3.7 Adsorption isotherms of RB 5 onto commercial coal - based activated carbon (single system)

5.7 Adsorption isotherms of RB 5 onto PKS- based activated

carbon (single system)

5.8 Adsorption isotherms of RR E onto PKS - based activated

carbon (single system)

5.8 Contact time study of the removal of RB 5 and RR E from

aqueous solutions using PKS - based activated carbon: Effect of initial dye concentrations (single system)

5.10

Contact time study of the removal of RB 5 and RR E from aqueous solutions using PKS - based activated carbon: Effect of adsorbent mass at dye concentration of 20 mg/L and mass of adsorbent 2g/L (single system)

5.12

First-order kinetic model for the removal of (a) RB 5 and (b) RR E from aqueous solutions using PKS - based activated carbon: Effect of initial dye concentration

5.13

First-order kinetic model for the removal of (a) RB 5 and (b) RR E from aqueous solution using PKS-based activated carbon: Effect of adsorbent mass

5.14

Pseudo second-order kinetic model for the removal of (a) RB 5 and (b) RR E from aqueous solutions using PKS - based activated carbon: Effect of initial dye concentration

5.18

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xvi Adsorption isotherms of BB 9 onto PKS - based activated

carbon: PKS-S

5.19

Contact time study of the removal of RR E from aqueous solutions using PKS - based activated carbon: Desorption phenomenon (single system)

5.22

Adsorption isotherms of (a) RB 5 and (b) RR E onto PKS - based activated carbon (binary system)

5.25 Comparison of adsorption kinetics of RB 5 and RR E for

single and binary component onto PKS-based activated carbon at dye concentration of 20 mg/L and mass amount of 2g/L

5.26

Comparison between prediction film-surface diffusion (S.D) and film-pore diffusion (P.D) models with experiments data from adsorption of RB 5 onto PKS-based activated carbon (single system)

5.29

Comparison between prediction film-surface diffusion (S.D) and film-pore diffusion (P.D) models with experiments data from adsorption of RR E onto PKS-based activated carbon at dye concentration of 20 mg/L and mass amount of 2g/L (single system)

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LIST OF NOTATIONS / SYMBOLS Notations / symbols Å Angstrom/Unit of length 10-10 m L α Langmuir constant L.mg-1 p

a Adsorbent Pellet Radius mm R

α Redlich-Peterson Constant (L/.mg)bR p

ρ Pellet Density mg.mm-3

λmax Max Wave Length of Adsorption nm

p

ε Porosity of Pellet

bij Correlation Constant in Empirical

Freundlich Isotherm for Binary system

R

b Redlich-Peterson isotherm exponent

bo

c Initial Value of cb mg.L-1 b

c Adsorbate Concentration in the Bulk of

Fluid

mg.L-1

S

C Adsorbate Concentration in the Fluid-Pellet Interface

mg.L-1

Ce Bulk Phase Concentration mg.L-1

Ct Concentration of the Solution at Time t mg.L-1

Dmeso Average Mesopore Diameter Å

Dmicro Average Micropore Diameter Å

p

D Pore Diffusivity cm2.sec−2 s

D surface diffusivity cm2.sec−2

K Constant of Henry’s Law L.g-1

KF Freundlich adsorption capacity mg.g-1

f

k Mass Transfer Coefficient .sec−1

cm

KL Langmuir constant L.g-1

R

K Redlich-Peterson isotherm constant L.g-1

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M Adsorbent mass g n Surface heterogenity

t

N Adsorption Rate at Time s −1 r Radial distance measured from the center of

a pellet

mm

RL Separation factor

t Time minute

p Partial Pressure of Adsorbate in Gas Phase o

p Vapor Pressure of Adsorbate

q Average Adsorbed-Phased Concentration mg.g-1 qe Solid phase concentration at equilibrium mg.g-1

s

q Adsorbed-Phase Concentration in the

Solution-Pellet Interface

mg.g-1

qt Solid Phase Concentration at TimeT mg.g-1

A

S Specific Surface of Activated Carbon m2.g-1

V Volume of Solution mL

Vmeso Mesopore Volume cm3.g-1

Vmicro Micropore Volume cm3.g-1

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xix AC Activated carbon

COD Chemical Oxygen Demand ELE Extended Langmuir Equation

EL-FE Extended Langmuir-Freundlich Equation

FPCDSD Film-Pore- Concentration Dependent Surface Diffusion GAC Granular Activated Carbon

MEFE Modified Extended Freundlich Equation MW Molecular Weight

PAC Powdered Activated Carbon PKS Palm Kernel Shell

PSD Particle Size Distribution RB 5 Reactive Black 5

RR E Reactive Red E

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CHAPTER 1

INTRODUCTION

1.1 Water Pollution as an Environmental Pollutions Problem

The environment and everything connected with the environment, are important for the public because most of our ecological systems such as air, water and soil are continuously contaminated by domestic and industrial pollutants. Pollution has been defined in various ways. It is considered as the release of unwanted substances to the environment by man in quantities that damage either the health or the resources itself. Water pollution involves the release of small amounts of substances directly through point sources or indirectly through non point sources. Industrial effluents from various industries like textile, dyestuffs, paper and pulp, distillery, olive oil mill and metal industries etc. are the major contributors to water pollution as they create more subtle effects on behavior, reproduction or even survival of biotic communities.

1.2 Textile Dyes Effluent

Industries such as textile, ceramic, paper, printing and plastic, use dye as their raw material. Thus they consume a considerable volume of water. Robinson et al. (2001) reported, approximately two percent of total reactive dyes manufactured in the world are discharged directly into aqueous effluent and ten percent of total dye manufactured are discharged during the textile dyeing process. As a matter of fact, more than 7 × 105 tons dyestuff, are being produced annually and being used extensively in textile, dyeing and printing industries (Meyer, 1981).

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The presence of dyes in water is undesirable. Even a very small amount of these coloring agents is highly visible and may be toxic to aquatic environment. Reactive dyes are the only dyes which bond covalently with the textile fabrics. These dyes contain chromophoric groups such as azo, anthraquinone, triarylmethane, etc. and reactive groups (e.g. vinyl sulfone, chlorotriazine, trichloropyrimidine, etc). that form covalent bonds with the fiber (Sumathi and Manju, 2000). Azo reactive dyes, being most water-soluble synthetic dyes with the widest variety of colors and structure are generally resistant to aerobic biodegradation. Conventional biological wastewater treatment is not able to degrade them. It may be due to the lack of necessary enzymes in the conventional biological treatment plants (Akhtar et al., 2005).

In Malaysia, one of the main pollution source of textile wastewater is generated from batik industry that comes from the dyeing processes. Remazol reactive dyes are, commercially a very important class of textiles dyes. Unadsorbed dyes, which enter the wastewater through processing, are significant and difficult to treat. Many physical and chemical treatment methods including adsorption, coagulation, precipitation, filtration, electrodialysis, membrane separation and oxidation have been used for the treatment of dye containing effluents. The adsorption process is one of the most efficient methods of removing pollutants from wastewater. Further, the adsorption process provides an attractive alternative treatment, especially if the adsorbent is inexpensive and readily available (Tan et al., 2000).

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1.3 Problem Statement and Objectives of the Study

Activated carbon is the most widely used adsorbent for the removal of color from textile effluents because it has a high capacity for organic matter. It is produced from organic based materials such as in this case, palm kernel shells. The raw material is carbonized to obtain the char or carbonaceous material, which is activated to yield the highly porous final product. Although adsorption process using activated carbon is promising in decolorizing textile effluents, this application is limited by the high cost of adsorbents (Robinson et al., 2001). Bailey et al. (1999) reported that, in general, a sorbent can be assumed as “low cost” if it requires little processing, is abundant in nature, or is a by-product or waste material from another industry. Thus, the activated carbon derived from agricultural wastes becomes important due to the fact that it is inexpensive, easy to access and adequate to remove organic and inorganic contaminants from wastewater (Mohan and Pittman, 2007). Some of the materials used for activated carbon are listed in Table 1.1.

Table 1.1: Some materials used as activated carbon.

Material Reference saw dust, rice husk Malik, 2003

peanut shells, cotton seed shell Kim et al., 2003 myrobalan, rubber seed coat, cashew nut

sheath, palm seed coat, palm tree flower, pongam seed coat

Rengaraj et al., 1999

cornelian cherry, apricot stone, almond shell

Demirbas et al., 2004 oak wood waste, corn hulls, corn stover

(corn stover consists of the leaves and stalks of maize plants left in a field after harvest)

Zhang et al., 2004

cotton stalk Attia et al., 2004

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Several studies were initiated to utilize palm kernel shell as the crude material for activated carbon and it is reported that a good quality product can be obtained, such as its granular structure, insolubility in water, chemical stability, high mechanical strength (Ma, 2002; Mak, 2003; Jumasiah et al., 2005; Choong et al., 2006).

Jumasiah et al. (2005) reported adsorption of basic dye using palm kernel shell-AC. The sorption kinetics and equilibrium of basic dye onto palm kernel shell activated carbon were studied. The study showed that the isotherm data were well described by the Redlich–Peterson isotherm model, where the sorption kinetics was fitted well by the pseudo-second-order kinetic model.

Choong et al. (2006) also reported therate of dye adsorption from aqueous effluents onto palm kernel shell-AC. The adsorption rates of methylene blue on PKS-AC for systems of different initial dye concentrations were modeled using a film-pore-concentration dependent surface diffusion (FPCDSD) model. The FPCDSD model was used to study the methylene blue/PKS system for different initial concentrations.

However, no study has been reported on the removal of reactive dyes using PKS-AC. There are also no works has been reported on study of binary reactive dyes adsorption on PKS-AC. Therefore, it is important to study the mechanism of this adsorption process in order to provide engineering information, such as uptake capacity and equilibrium time, for adsorbent design.

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In this study, palm kernel shell was evaluated for its ability to remove reactive dyes,

i.e. Reactive Black 5 and Reactive Black E, from aqueous solution by sorption. The

objectives of this work are:

1. To investigate the adsorption isotherm of single and binary reactive dyes, Remazol black and Remazol red, on palm kernel shell-based activated carbon.

2. To evaluate the adsorption kinetics of single and binary reactive dyes, Remazol black (Reactive Black 5) and Remazol red (Reactive Black E), on palm kernel shell-based activated carbon.

3. To model the adsorption of reactive dyes on PKS-AC using film resistance model, film-surface and film-pore diffusion models to study their diffusion mechanism.

References

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