REMOVAL OF CONGO RED BY USING ADSORPTION ONTO PALM OIL WASTE

MUBARAK BIN AMIR

FACULTY OF CHEMICAL ENGINEERINGUNIVERSITI TEKNOLOGI MARA

PULAU PINANG

REMOVAL OF CONGO RED BY USING ADSORPTION ONTO PALM OIL WASTE

MUBARAK BIN AMIR

This report is submitted in partial fulfillment of the requirements needed for the award of Diploma of Chemical Engineering

FACULTY OF CHEMICAL ENGINEERINGUNIVERSITI TEKNOLOGI MARA

PULAU PINANG

MAY 2008

DECLARATION

“I hereby declare that this report is the result of my own work except for quotations and summaries which have been duly acknowledged.”

Mubarak Bin Amir 12 May 20082005491176

ii

SUPERVISOR’S CERTIFICATION

“I hereby declare that I have read this thesis and in my opinion this project report is sufficient in terms of scope and quality for the award of the Diploma of Chemical

Engineering.”

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

iii

Accepted:

Signed :…………………………

Date :…………………………

Coordinator

Puan Siti Aminah Binti Mohd Ali

Faculty of Chemical Engineering

Universiti Teknologi MARA

Pulau Pinang

iv

ACKNOWLEDGEMENT

I would like to express my sincere gratitude and appreciation to my supervisor, Puan Ainnie Rahayu Bte Abdullah of Department of Applied Sciences, UiTMPP for her support and invaluable advice with a continuous stream of suggestions, feedback, and encouragement that have guided me throughout the whole period of my final year project. I especially would like to thank her for always being accessible and making research her top priority. I would also like to thank Dr. Nor Aziyah Bte Bakhari of Department of Applied Sciences, UiTMPP for her constructive comments, suggestions and salient advice. The Laboratory’s technicians of Environmental, Geotechnic and Chemistry for their help in finishing of this project. I would like to thank the faculty and staff in the Faculty of Chemical Engineering for their continuous support and high quality education. I would like to thank all the present students of Chemical Engineering, especially Abdul Hakim Bin Mohd Fadzil, Mohd Shafiq Bin Yusof and Mohd Syafiq Rahman Bin Abd Rahman for their friendship and contributions to my project. In particular, I want to give my special thanks to Mr. Hazreeq Bin Ramli of Engineering Faculty of Universiti Putra Malaysia for his detailed and thoughtful comments, tremendous help, analytical method development and friendship that made my introduction to laboratory life a wonderful experience. Many thanks to all students of Chemical Engineering for creating a stimulating and supportive environment, and all my friends at Universiti Teknologi MARA, who have made another part of my life full of joy and excitement. I would like to thank Abdul Hakim Bin Mohd Fadzil for his kindness and friendship while completing my report, and especially for embarking on my life’s journey with me. Finally, my sincere warmhearted gratitude goes to my parents for their endless love, understanding, patience and support. Without them, none of my accomplishments would have been possible. To them, I dedicate this report.

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ABSTRACT

Dyes are usually present in trace quantities in the treated effluents of many industries. The effectiveness of adsorption for dye removal from wastewaters has made it an ideal alternative to other expensive treatment methods. This study investigates the potential use of palm oil waste for the removal of Congo red, an azo dye from simulated wastewater. The effects of varying parameter such as adsorbent dosage, initial dye concentration and contact time were studied by batch adsorption procedure. The results showed that as the amount of the adsorbent was increased, the percentage of dye removal increased accordingly. As the amount of adsorbent dosage was increased from 0.5g/100mL to 2.0g/100mL, the percent of dye removal was increased by 60.4% from 33.2% to 83.9% at 300 minutes leading to the optimum contact time. Higher adsorption percentages were observed at lower concentrations of Congo red. For instance, the percent of dye removal was found to be 65.0% at the initial dye concentration of 10mg/L instead of 53.0% at the initial dye concentration of 50mg/L at optimum contact time of 300 minutes. Palm oil waste showed an average performance in terms of efficiency of dye removal compared to some other agricultural wastes, thus making it an interesting option for dye removal from dilute industrial effluents.

vi

CONTENTS

TITLE PAGE

AUTHOR’S DECLARATION ii

SUPERVISOR’S CERTIFICATION iii

COORDINATOR’S CERTIFICATION iv

ACKNOWLEDGEMENT v

ABSTRACT vi

LIST OF TABLES ix

LIST OF FIGURES x

LIST OF PLATES xi

CHAPTER 1 INTRODUCTION

1.1 General Overview 1

1.2 Problem Statement 2

1.6 Objectives of Project 4

CHAPTER 2 LITERATURE REVIEW

2.1 Dyes 5

2.1.1 Congo Red 6

2.1.1 (a) Behavior in Solution 7

2.1.1 (b) Dyeing Activity 7

2.2 Treatment of Dyes 7

2.2.1 Physical Treatment 8

2.2.2 Chemical Treatment 8

2.2.3 Biological Treatment 9

2.3 Adsorption 11

2.3.1 Types of Adsorption 12

2.3.1 (a) Physical Adsorption 12

2.3.1 (b) Chemical Adsorption 13

2.3.2 Factors Influencing Adsorption 13

2.3.2 (a) Effect of Contact Time 13

2.3.2 (b) Effect of Initial Concentration 14

2.1.2 (c) Effect of Adsorbent Molecular Size 14

2.1.2 (d) Effect of pH 14

vii

2.1.2 (e) Effect of Temperature 15

2.1.2 (f) Effect of Adsorbent Characteristic 15

2.1.2 (g) Effect of Solubility of Adsorbent 15

2.4 Adsorbent 16

2.4.1 Activated Carbon 16

2.4.2 Non-Conventional Activated carbon 17

2.4.2 (a) Palm Oil and Palm Oil Waste 17

CHAPTER 3 METHODOLOGY

3.1 Experimental Work 19

3.2 Chemicals 19

3.3 Apparatus and Equipments 19

3.4 Adsorbent Preparation 20

3.5 Preparation of Anionic Dye Solutions 22

3.6 Procedure 22

3.6.1 Weight of Adsorbent 22

3.6.2 Contact Time 23

3.6.3 Shaking Speed 23

3.7 Adsorption Studies 24

CHAPTER 4 RESULTS AND DISCUSSIONS

4.1 Preliminary Result 26

4.1.1 Color Observation 26

4.2 Experimental Results 27

4.2.1 Effect of Contact Time 31

4.2.2 Effect of Initial Concentration 33

CHAPTER 5 CONCLUSION AND RECOMMENDATIONS

5.1 Summary and Conclusion 35

5.2 Recommendations / Future Work 36

REFERENCES 38

viii

LIST OF TABLES

TABLE TITLE PAGE

2.1 Different Techniques Used For Dye Decolorization 10

2.2 Comparison for Adsorption of Some Dyes on Various Adsorbents 17

4.1 Tabular Data of the First Trial 26

4.2 Tabular Data of the Second Trial 26

4.3 Tabular Data of the Third Trial 27

4.4 Average to the Triplicate Trial 27

4.5 Effect of Adsorbent Dose on the Dye Adsorption 30

4.6 Effect of Congo Red Concentration on the Dye Adsorption 32

ix

LIST OF FIGURES

FIGURE TITLE PAGE

2.1 Chemical Structure of CR Dye 06

2.2 Micropores 10

2.3 Activated Carbon Pore Structures 15

2.4 Palm Oil Wastes 16

4.2 Effect of Adsorbent Dosage on Removal of CR 29

4.3 Removal of CR as a Function of Equilibrium Time 31

x

LIST OF PLATES

PLATE TITLE PAGE

3.1 Raw Material of Palm Oil Waste 18

3.2 Palm Oil Waste Washed With Water and Remove the 18

Precipitate Before Drying in Multi Point at 110°C

3.3 Final Products after Drying Process 19

3.4 Dryer Multi Point 19

3.5 Auto Sieve Shaker D408 ENDECOTTS 19

3.6 Orbital Shaker SK-600 21

3.7 UV/VIS Spectrophotometry (Shimadzu UV-160 A) 22

3.8 Delta 320 pH Meter 23

4.1 Comparison of Color Changes Before (left) and 25

After (right) Treatment

xi

CHAPTER 1

INTRODUCTION

1.1 GENERAL OVERVIEW

The use of chemicals such as alum, ferric, chloride, polymer flocculants and coal

based activated carbon as conventional wastewater treatment are not practically

and cost effective for many developing countries. In Malaysia, for instance, to be

one of the world’s fast developing countries, the problems such as wastewater

treatment might be the government vital focus towards industrial areas. An

economically viable alternative for the removal of pollutants by adsorbent that is

easily available and for sure inexpensive and affordable by the industries would

cater the needs of wastewater treatment. For instance, the vast of agricultural areas

such as palm oil plantation, rubber plantation and many others across the country

has its own advantage due to the waste produced. In this project, the use of palm

oil waste for the removal of Congo Red (CR) by using adsorption method from

wastewater was adapted to suit the effective in cost and more practical means to the

scenario in Malaysia.

The major problem in the treatments of waters that contain azo-dyes is due

to the high stability of these species. Dyes are resistant to light and oxidation

agents moderately, thus they cannot be completely treated by conventional methods

of anaerobic digestion (Panswed et. al, 1986). Some procedures can be used for

treating waters containing dyes, for instance, coagulation and flotation (Malik PK et.

al, 2003), ozonization (Koch M et. al, 2002), membrane separation (Deo Mall I et. al,

2005) and adsorption by activated carbon (Namasivayam C et. al, 2003). The

adsorption process at solid or liquid interface has been extensively employed for

several reasons, mainly due to its efficiency and economy (Espantaleon et. al,

2003). Nevertheless, the used of activated carbon adsorption is the most popular

physico-chemical treatment for the removal of dissolved organics from wastewaters.

Adsorption studies for dye removal have been carried out using activated carbon

1

made from non-conventional sources as adsorbents (MM. Howlader et. al, 1999)

where in this project; palm oil waste was fully utilized.

Many industries such as paper, food, cosmetics, textiles etc. use dye in

order to colour their products. The presence of these dyes in water even at very low

concentration is highly visible and undesirable. Colour is the first contaminant to be

recognized. Textile dyeing operations are generally small-scale processes that use

highly variable colorant formulations and fresh water quantities, depending upon the

required characteristics of the final product. Azo dyes are the most widely used

colorants, accounting for up to 70 % of the overall colorant production (Chiang et. al,

2000). The wastewaters generated from dyeing operations contain unreacted

organic colorants and inorganic fixing agents that result in strong color coupled with

variable ionic strength and pH. Aside from being an aesthetic problem, colorant

substances are often biologically-recalcitrant and may cause both acute and chronic

health disorders to organisms exposed to them.

Adsorption methods offer a good potential to remove colour from

wastewater. In the present project this method was employed for removal of Congo

red and it was found to be very useful and cost effective for a better removal of dye

and the results were recorded. The operating variables such as adsorbent dose,

adsorbate concentration, pH etc were optimised.

1.2 PROBLEM STATEMENT

Synthetic dyes are extensively used in many industries such as the textile, leather

tanning, paper production, food technology, hair colorings, etc. Wastewaters

discharged from these industries are usually polluted by dyes. Congo red (CR) is

most commonly used for the dyeing of cotton, silk, paper, leather and also in

manufacturing of paints and printing inks. Congo red is widely used in distilleries for

coloring purposes (Khattri et. al., 1999). Congo red has properties that make it

difficult to remove from aqueous solutions and also toxic to major microorganisms

(Papinutti et. al., 2006). Congo red when discharged into receiving streams will

affect the aquatic life and causes detrimental effects in liver, gill, kidney, intestine,

gonads and pituitary gonadotrophic cells (Srivastava et. al., 2004). Therefore, the

treatment of effluent containing such dye is of interest due to its esthetic impacts on

receiving waters.

2

Dyes are common constituents of effluents discharged by various

industries, particularly the textile industry. The presence of small amounts of dyes in

water is highly visible and undesirable (Crini, 2006). Recently, an increasing interest

has been focused on removing dyes from water due to its refractory biodegradation

and toxic nature, which affects the aquatic biota and food web (Gregory et al.,

1991). Adsorption technique is quite popular due to its simplicity as well as the

availability of a wide range of adsorbents and it is proved to be an effective and

attractive process for removal of non-biodegradable pollutants (including dyes) from

wastewater (Aksu, 2005).

The common adsorbent, activated carbon, has good capacity of removal of

pollutants (Walker and Weatherley, 1997) and (Walker and Weatherley, 1998). But

its main disadvantages are the high price of treatment and difficult regeneration,

which increases the cost of wastewater treatment. Thus, there is a demand for

other adsorbents, which are of inexpensive material and does not require any

expensive additional pretreatment step. So the adsorption process will become

economically viable. A successful adsorption process not only depends on dye

adsorption performance of the adsorbents, but also on the constant supply of the

materials for the process. So it is preferable to use low cost adsorbents, such as an

industrial waste, natural ores, and agricultural byproducts. This has resulted in a

search for developing other adsorbents based on solid wastes. Such low cost

adsorbents have given satisfactory performance at the laboratory scale for treatment

of colored effluents (Sivaraj et al., 2001).

3

1.3 OBJECTIVES OF PROJECT

The project was focused on the dye removal by palm oil waste, one of an

agricultural (non-conventional) adsorbent. It was conducted by evaluating the

adsorption capacity of palm oil waste with the relevant parameters. The specific

objectives of this project are as follows:

i. To study the effects of contact time on Congo red removal.

ii. To study the effects of initial dye concentration on Congo red removal.

iii. To study the effects of adsorbent dosage on Congo red removal.

4

CHAPTER 2

LITERATURE REVIEW

2.1 DYES

A dye can generally be described as a colored substance that has an affinity to the

substrate to which it is being applied. The dye is generally applied in an aqueous

solution, and may require a mordant to improve the fastness of the dye on the fiber.

Both dyes and pigments appear to be colored because they absorb some

wavelengths of light preferentially. In contrast with a dye, a pigment generally is

insoluble, and has no affinity for the substrate. Some dyes can be precipitated with

an inert salt to produce a lake pigment. Archaeological evidence shows that,

particularly in India and the Middle East, dyeing has been carried out for over 5000

years. The dyes were obtained from animal, vegetable or mineral origin, with no or

very little processing. By far the greatest source of dyes has been from the plant

kingdom, notably roots, berries, bark, leaves and wood, but only a few have ever

been used on a commercial scale.

Dyes are recalcitrant by design and not readily amendable to common

treatment methods, imposing a challenge for closing industrial water systems.

Extensive research in the field of biological azo dye decolorization has shown

promising results (Cervantes et. al, 2001; Dos Santos et. al, 2003). However,

industrial textile wastewater presents the additional complexity of dealing with

unknown quantities and varieties of many kinds of dyes (Bisschops and Spanjers,

2003), as well as low BOD/COD ratios, which may affect the efficiency of the

biological decolorization. Many microorganisms are able to anaerobically reduce

azo dyes producing anaerobically recalcitrant aromatic amines (Chung et al., 1995).

However, many of these amines are readily mineralized aerobically, so an

anaerobic-aerobic treatment strategy has been proposed as a feasible treatment

strategy (Tan et. al, 2000).

5

2.1.1 Congo Red

Different adsorbent materials have been used to removes dyes from waters. In this

work, the palm oil waste was used as adsorbent to remove Congo red (that in this

work was simply designated as CR) from synthetic wastewater. Congo Red, (1-

naphthalenesulfonic acid, 3,3’ – (4,4’ – biphenylenebis (azo)) bis (4 – amino -)

disodium salt) [C.I. = 22120, chemical formula = C32H22N6Na2O6S2, FW = 696.7, λmax

= 500 nm] is a benzidine-based anionic disazo dye. This dye is known to

metabolize to benzidine, a known human carcinogen. It is widely used in textiles,

paper, rubber and plastic industries. Due to its structural stability, CR is difficult to

biodegrade. The chemical structure of the CR dye contains NH2 and SO3 functional

groups as illustrated in Figure 2.1 below. In the environment view-point, the removal

of color from aquatic systems caused by the presence of synthetic dyes that majorly

contains azo-aromatic groups is tremendously important due to its carcinogenic,

mutagenic and toxic effects (Gregory AR et. al, 1991). For drinking purpose and

other uses, colored waters are strictly objectionable an aesthetic grounds for human

daily lives.

In addition, the presence of dye on natural water systems restraints sunlight

diffusion into the water, thus, reduces the photosynthetic process of aquatic plants

(Gong R et. al, 2005). Discharge of wastewater into natural streams and rivers from

the industries using dyes poses severe environmental problems where even small

quantities of dyes can color large water bodies that finally obstruct the natural

process of photosynthesis. CR represent one of the problematic groups; they are

emmited into wastewaters from various industries branches, mainly from the dye

manufacturing and textile finishing (Janos et. al, 2003) and also from food colouring,

cosmetics, paper and carpet industries (Indra DeoMall et. al, 2004).

Figure 2.1 Chemical structure of CR dye

6

2.1.1 (a) Behavior in Solution

Due to a color change from blue to red at pH 3.0-5.2, Congo red can be used as a

pH indicator. Since this color change is an approximate inverse of that of litmus, it

can be used with litmus paper in a simple parlor trick: add a drop or two of Congo

red to both an acid solution and a base solution. Dipping red litmus paper in the red

solution will turn it blue, while dipping blue litmus paper in the blue solution will turn it

red. Congo red has a propensity to aggregate in aqueous and organic solutions.

The proposed mechanisms suggest hydrophobic interactions between the aromatic

rings of the dye molecules, leading to a pi-pi stacking phenomenon. Although these

aggregates are present under various sizes and shapes, the "ribbon-like micelles" of

a few molecules seem to be the predominant form (even if the "micelle" term is not

totally appropriate here). This aggregation phenomenon is more important for high

Congo red concentrations, at high salinity and/or low pH.

2.1.1 (b) Dyeing Activity

As suggested by its intense red color, Congo red has important spectrophotometric

properties. Indeed, its UV-visible absorption spectrum shows a characteristic,

intense peak around 498 nm in aqueous solution, at low dye concentration. Congo

red molar extinction coefficient is about 45000 [L]/[mol].[cm] in these conditions.

Aggregation of the dye tends to red-shift the absorption spectrum, whereas binding

to cellulose fibres or amyloid fibrils has the opposite effect. Congo red also shows a

fluorescent activity when bound to amyloid fibrils, which tends to be used as a

sensitive diagnosis tool for amyloidosis, instead of the traditional histological

birefringence test.

2.2 TREATMENT OF DYES

Many processes have been used and/or researched for dye treatment from

wastewater. A brief description of dye treatment of each process compiled from

literature is summarized in Table 2.1. However, not all processes work for all

colored wastewaters (Hao et al., 2000; Robinson et al., 2001; Naim and Abd, 2002).

Some studies have reported successful decolorization using different treatment

schemes, despite the fact that the treated wastewater still has low color intensity.

7

Only a few cases have being reported with complete decolorization and dye

mineralization (Hao et al., 2000; Robinson et al., 2001; Naim and Abd, 2002).

2.2.1 Physical Treatment

Activated carbon is the most used method of dye decolorization by adsorption, and

is very effective for adsorbing cationic, mordant and acid dyes (Nasser and El-

Geundi, 1991; Raghavachraya, 1997). Numerous other adsorbents, such as peat,

wood chips, fly ash, and brown coal have been used as dye adsorbents (Nigam et

al., 2000; Robinson et al., 2001). However, although adsorption can efficiently

decolorize textile effluents, its application has been limited by the high cost of

adsorbents and the large volume of wastewater normally involved (Robinson et al.,

2001; Naim and Abd, 2002). Nanofiltration removed up to 99% of a variety of

reactive dyes in laboratory studies (Wu et al., 1998) and has been successfully

applied in a pilot-scale study (Chen et al., 1997). Rozzi and coworkers (1999)

employed a microfiltration unit followed by a nanofiltration unit or a reverse osmosis

membrane process for a potential textile wastewater reuse. Nonetheless, the use of

membrane processes for large flow rates is prohibitively costly, in addition to the

common problems of membrane processes with respect to flux decline, irreversible

fouling, and required treatment and disposal of the concentrate (Van’t Hul et al.,

1997; Hao et al., 2000; Naim and Abd, 2002).

2.2.2 Chemical Treatment

Chemical oxidation is the most frequently used decolorization process in research

and applied in industry, partly due to the diversity of chemical processes that can be

effective. Chemical oxidation removes the dye from the dye-containing effluent by

oxidation resulting in aromatic ring cleavage of the dye molecules (Raghavacharya,

1997; Robinson et al., 2001). Recently, many advanced oxidation processes, such

as the Fenton’s reagent (H2O2 and Fe2+), UV light with or without catalysis (e.g.,

TiO2), H2O2, and ozone (O3), have been evaluated for the decolorization of textile

wastewater (Hao et al., 2000; Robinson et al., 2001; Naim and Abd, 2002).

8

2.2.3 Biological Treatment

Many researchers have demonstrated the biological decolorization of dyes by pure

and mixed cultures of fungi and bacteria. The use of ligninolytic fungi is one of the

possible alternatives studied for the biodegradation of dyes. Fungi can mineralize

xenobiotic compounds to CO2 and H2O through their highly oxidative and non-

specific ligninolytic system, which is also responsible for the decolorization and

degradation of a wide range of dyes (Fu and Viraraghavan 2001; McMullan et al.,

2001; Wesemberg et al., 2003; Pinheiro et al., 2004). Since degradation of dyes by

the white-rot fungi was first reported by Glenn and Gold (1983), white-rot fungi have

been the most widely studied, dye-decolorizing microorganisms. Fungi such as

Phanerochaete chrysosporium, Pleurotus, Bjerkandera, Trametes, Poyporus,

Phelinus, Iperx lacteus, Funalia trogii, and Thelephora sp., have been investigated

for the decolorization and mineralization of various dyes (Fu and Viraraghavan

2001; Selvam et al., 2003; Wesemberg et al., 2003; Yesilada et al., 2003).

9

Table 2.1: Different techniques used for dye decolorization

a Krupa and Cannon, 1996b Wu et al., 1998c Muruganandham and Swaminathan, 2004

PROCESS DYEINFLUENT DYE CONC.

(COLOR MEASUREMENT)

TREATMENT

PROCESSCOMMENTS

Adsorption Orange Red, Crystal

Violet and Methylene

Blue

200 mg/L

(respective αmax)

Sorption capacity of

different activated

carbons

Equilibrium capacity various with dyes and

carbons; correlated well with mesophore

and large micropore volumea

Membrane Various dyes to

simulate textile waste

Integration of the area

under A400-700

Polysulfone nanofiltration

membrane with total

area of 10 m2

99% color removal by a particular

polyamide membrane at 20°C and 180 psib

Fenton and

photo-Fenton

Reactive Orange 4 100-400 mg/L

(respective αmax)

Varying pH, Fe2+, H2O2

and UV light intensity

98% color removal; photo-Fenton process is

more efficientc

Photocatalytic

(TiO2)

Orange II 50 mg/L

(respective αmax)

TiO2 catalysts supported

on three different

absorbents

Over 95% color removal; TiO2 supported on

absorbents is more efficient than that of

bare TiO2

Ozonation and

ultrasound-

enhanced

ozonation

Reactive Blue 19 30 mg/L

(respective αmax)

Varying ozone, and

ultrasound enhanced

ozone operational

conditions

First-order rate constants increased by

200% for ultrasonic power inputs compared

to ozonation alonec

10

2.3 ADSORPTION

The use of solids for removing substances from either gaseous or liquid solutions

has been widely used since biblical times. This process, known as adsorption,

involves nothing more than the preferential partitioning of substances from the

gaseous or liquid phase onto the surface of a solid substrate. From the early days

of using bone char for decolorization of sugar solutions and other foods, to the later

implementation of activated carbon for removing nerve gases from the battlefield, to

today's thousands of applications, the adsorption phenomenon has become a useful

tool for purification and separation. Adsorption phenomena are operative in most

natural physical, biological, and chemical systems, and adsorption operations

employing solids such as activated carbon and synthetic resins are used widely in

industrial applications and for purification of waters and wastewaters.

The process of adsorption involves separation of a substance from one

phase accompanied by its accumulation or concentration at the surface of another.

The adsorbing phase is the adsorbent, and the material concentrated or adsorbed at

the surface of that phase is the adsorbate. Adsorption is thus different from

absorption, a process in which material transferred from one phase to another (e.g.

liquid) interpenetrates the second phase to form a "solution". The term sorption is a

general expression encompassing both processes. Physical adsorption is caused

mainly by van der Waals forces and electrostatic forces between adsorbate

molecules and the atoms which compose the adsorbent surface. Thus adsorbents

are characterized first by surface properties such as surface area and polarity. A

large specific surface area is preferable for providing large adsorption capacity, but

the creation of a large internal surface area in a limited volume inevitably gives rise

to large numbers of small sized pores between adsorption surfaces.

The size of the micropores determines the accessibility of adsorbate

molecules to the internal adsorption surface (see Figure 2.2), so the pore size

distribution of micropores is another important property for characterizing

adsorptivity of adsorbents. Especially materials such as zeolite and carbon

molecular sieves can be specifically engineered with precise pore size distributions

and hence tuned for a particular separation. Surface polarity corresponds to affinity

with polar substances such as water or alcohols. Polar adsorbents are thus called

"hydrophillic" and aluminosilicates such as zeolites, porous alumina, silica gel or

silica-alumina are examples of adsorbents of this type. On the other hand, nopolar

11

adsorbents are generally "hydrophobic". Carbonaceous adsorbents, polymer

adsorbents and silicalite are typical nonpolar adsorbents. These adsorbents have

more affinity with oil or hydrocarbons than water.

Figure 2.2 Micropores

2.3.1 Types of Adsorption

Most adsorption processes in wastewater treatment are combination of neither

purely physical nor purely chemical processes. It is difficult to distinguish between

these two processes and such distinction is not necessary in order to analyzed and

design the adsorption processes (Benefield, 1982). Adsorption processes occurs in

both conditions whether steady or unsteady state. The primary force driving the

interaction between the adsorbate and the adsorbent is the electrostatic attraction

and repulsion between molecules of the adsorbate and the adsorbent. This driving

force can be either physical or chemical (Alley, 2000).

2.3.1 (a) Physical Adsorption

Physical adsorption or physisorption is a result of intermolecular forces such as Van

der Waals and dipole forces between the adsorbent and the adsorbate. The

adsorbed molecule is not affixed to the adsorbent during physical adsorption but it is

free to move about the surface of the adsorbent (The, 1999). Physical adsorption is

a readily reversible reaction and includes both mono and multilayer coverage of

adsorbate molecular on the adsorbent’s surface (Alley, 2000).

12

2.3.1 (b) Chemical Adsorption

Chemical adsorption or chemisorption is occurred as a result of a chemical reaction

between the adsorbate molecule and the adsorbent (Benefield, 1982). Chemical

adsorption creates high stronger forces, which involves the actual chemical bonding

of the adsorbents surface to a solute, compare to those lead formation of chemical

compounds. The adsorbed molecules make a layer over the surface that is only

one molecule thick and are relatively not free to move from one surface site to

another surface (The, 1999). Abu Foul (2007) cited that this type of adsorption is

thought to occur on the sides and corners of the micro-crystallites that compromise

the activated carbon.

2.3.2 Factors Influencing Adsorption

Molecules of solute are removed from solution and taken up by the adsorbent during

the process of adsorption. The majority of molecules are adsorbed onto the large

surface area within the pores of adsorbent particles and relatively few are adsorbed

on the outside surface. These transfer process continue until equilibrium is

achieved (Benefield et al., 1982). Many factors affect the rate at which adsorption

reaction occurs and the extent to which a particular material can be adsorbed.

These factors included contact time, initial concentration, adsorbent, characteristics,

size of adsorbate molecules, solubility of the adsorbate, pH and temperature (Abu

Foul, 2007).

2.3.2 (a) Effect of Contact Time

In general, adsorption increases with the increase in contact time until equilibrium is

reached (Sag and Aktay, 2002). Contact time in the adsorption system affects the

rate adsorption, which is controlled by either, film diffusion or pore diffusion. If the

contact time is relatively small, the surface film of liquid around the particle will be

thick and film diffusion will likely be the rate-limiting step. If adequate contact time is

provided, film diffusion rate will increase to the point that pore diffusion becomes the

rate-limiting step (Benefield et al., 1982).

13

2.3.2 (b) Effect of Initial Pollutant Concentration

Effect of initial pollutant concentration is one of the factors that influence the rate of

the adsorption. Generally, the rate of adsorption decreases as initial pollutants

concentration increases. This is because the adsorption sites adsorb the available

molecules more quickly at low concentrations (Alley, 2000; Sag and Aktay, 2002).

2.3.2 (c) Effect of Adsorbent Molecular Size

Molecular size would logically be important in adsorption; since the molecules must

enter the micropores of an adsorbent so as to be adsorbed. Research has shown

that within a homologous series of aliphatic acids, aldehydes, or alcohol, adsorption

usually increases as the size of molecule increase (Benefield et al., 1982).

Substances of the highest molecular weight are most easily adsorbed. The rates

are reciprocally with the square of the particle diameter (Eckenfelder, 1989).

2.3.2 (d) Effect of pH

The pH at which adsorption is carried out has been shown to have a strong

influence on the extent of adsorption. This is partly due to the fact that hydrogen

ions themselves are strongly adsorbed and partly that pH influences the ionization,

of many compounds. Organic acids are more adsorbed at low pH, whereas the

adsorption of organic bases is favored by high pH. In general, metal adsorption

increases as pH increases (Seco et al., 1999; Evans et al., 2002).

Isa et al., (2006) suggested that the optimum pH value for the adsorption of

colour occurred at acidic conditions. This is due to the positive charge dominating

the surface of the adsorbent which slightly increase the electrostatic attraction

between the negatively charged dye species and the positively charged surface of

the adsorbent (Namasivayam and Kavitha, 2002). In removal of COD, lower PH

values give greater removal. At lower value of pH, the precipitation of solids will

increase which improves the removal efficiency of COD. Removal of iron at acidic

condition is better than at alkaline conditions. Higher removal of iron efficiency at

pH over 10 may be contributed by the effect of adsorption and precipitation (Isa et

al. 2004).

14

2.3.2 (e) Effect of Temperature

In adsorption process, temperature does take affect in rate of adsorption and the

extent to which adsorption occurs. Generally adsorption rates increase with

increase in temperature. However since the adsorption is generally an exothermic

process, the degree of adsorption will increase at lower temperature and increase at

lower temperature and decrease at higher temperature (Benefield et al., 1982).

According to Kobya, (2004) adsorption capacity of activated carbon increased with

increasing temperature.

2.3.2 (f) Effect of Adsorbent Characteristic

Adsorbent molecular size is an important factor in adsorption since molecule must

pass through the micropores of an adsorbent as to be adsorbed. Researches have

proved that adsorption usually increases as the size of molecule increases within a

homologous series of aliphatic acids, aldehydes or alcohol (Benefield et. al, 1982).

Particle size, chemical structure and surface area are important properties

of media with respect to its use as an adsorbent. Adsorption rate increases as

adsorbent particle size decreases (Benefield et al., 1982). Generally the total

adsorptive capacity of adsorbents depends on its total surface area (Sag and Aktay,

2002).

2.3.2 (g) Effect of Solubility of The Adsorbent

In adsorption process, a molecule must be separated from the solvent before

attached to the adsorbent surface. Generally, soluble compounds are more difficult

to adsorb rather than insoluble compounds because of the strong affinity for their

soluble. However, there are exceptions since many compounds are difficult adsorb

even though in slightly soluble. Some compounds which are very soluble may be

adsorbed readily (Benefield at al., 1982).

15

2.4 ADSORBENT

Adsorbents are the material used to adsorb the adsorbate. There are several types

of adsorbents that have been used which are activated carbon, zeolite, organic

polymers, palm ash, limestone, clay mineral, sepiolite, Indian rosewood, chitosan,

commercial activated carbon, activated carbon prepared from agricultural waste,

fungus Aspergillus’s, limestone and activated carbon, sand and activated carbon

and also sulphur and limestone (Abu Foul, 2007).

2.4.1 Activated Carbon

Activated carbon is an adsorbent that contain highly porous carbonaceous

substance. It is a common term of products that consist primarily of elemental

carbon. Because of its inherent properties, large surface area, microporous

structure, high adsorption capacity and surface reactivity, activated carbon becomes

well-liked adsorbent for the removal of organic and inorganic pollutants from

leachate (Kurniawan et al., 2006). Activated carbon macropores have an effective

radius of 5000 to 20000 Angstroms (Angstroms = 10-10m) and open directly to the

outer surface of the carbon particle. Transitional pores with radius of 40 to 200

Angstroms develop off the macropores, whereas the micropores with an effective

radius of 18 to 20 Angstroms develop off transitional pores (Benefield et al., 1982).

Micropores are the most important property in the adsorption process. Figure 2.3

show the sample and structure of activated carbon.

Figure 2.3 Activated carbon pore structures (Source: Impregnated Activated Carbon for

Environment Protection, 1997)

16

2.4.2 Non-Conventional Activated Carbon

Due to the low-cost factor, an agricultural or non-conventional activated carbon has

been tested for the efficiency as an adsorbent. The use of agricultural wastes such

as wood (H.M. Asfour et. al, 1985), Fuller’s earth and fired clay (G. McKay et. al,

1985), fly ash (S.K. Khare et. al, 1987), biogas waste slurry (C. Namasivayam et. al,

1992), waste Fe(III)/Cr(III) hydroxide (C. Namasivayam et. al, 1994), waste orange

peel (C. Namasivayam et. al, 1996), banana pith (C. Namasivayam et. al, 1992),

peat (G. McKay et. al, 1982), chitin (G. McKay et. al, 1983), chitosan (R.S. Juang et.

al, 1997) and silica (G. McKay et. al, 1984) was reported with favor results as

expected. Comparison for adsorption of some dyes on various adsorbents is shown

in Table 2.2 below.

Table 2.2: Comparison for adsorption of some dyes on various adsorbents

Adsorbent(s) Dye(s) References

Duckweed Methylene blue (Waranusantigul et. al., 2003)

Sewage Sludge Basic red 46 (Martin et. al., 2003)

Waste newspaper Basic blue 9 (Okada et. al., 2003)

Rice husk Malachite green

Acid yellow 36

Acid blue

(Guo et. al., 2003)

(Malik et. al., 2003)

(Mohamed et. al., 2004)

Sugarcane bagasse Acid orange 10 (Tsai et. al., 2001)

Coir pith Congo red (Namasivayam et. al., 2002)

Straw Basic blue 10 (Kannan et. al., 2001)

2.4.2 (a) Palm Oil and Palm Oil Waste

The oil-palm (Elaeis guineensis Jacq.) was originally planted in West Africa, where

local people have used it to make foodstuffs, medicines and wine. At the present

time, oil-palm exists in a wild, semi-wild and cultivated state in the three land areas

of equatorial tropics: Africa, South-East Asia and America (Hartley et. al, 1988).

Today large scales of oil-palm plantations are mostly for the production of palm oil,

which is extracted from the flesh part of the palm fruit (mesocarp), and kernel oil,

which is obtained from the innermost nut. Agricultural wastes like the palm oil waste

are discarded in the agricultural sector in Malaysia as illustrated in Figure 2.4. As

17

one of the biggest producer and exporter of palm oil in the world, the abundant of

resources might be an advantage to the needs of this project.

Figure 2.4 Palm oil wastes

Palm oil wastes are the main biomass resources in ASEAN countries. In

Malaysia and Indonesia, the two largest palm oil producing countries in the world,

there were 30 M ton and 8.2 M ton of palm oil wastes (empty fruit bunch, fiber, palm

oil shell) generated respectively in year 2000, and they are increasing at spectacular

pace with the rapidly expanding of food and manufacturing industries. To treat this

tremendous amount of wastes, novel technologies with improved efficiencies and

reduced environmental impacts need to be established timely. In Malaysia itself, the

annual production is around 14 million tons from more than 38,000 square

kilometers of land, making it the largest exporter of palm oil in the world. To fully

utilize this abundant resource, in the present study I was analyzed by experimental

observation, the use of palm oil waste as the non-conventional adsorbent to remove

dye from wastewaters.

18

CHAPTER 3

METHODOLOGY

3.1 EXPERIMENTAL WORK

The present work was conducted in Environmental Laboratory and Geotechnic

Laboratory of Faculty of Civil Engineering, Ground Floor of Perdana Complex and

Chemistry Laboratory 2 and 3 Applied Sciences Department, 2nd Floor of Perdana

Complex, UiTM Penang. The experimental work consists of several phases which

are to determine the effect of shaking time, contact time and weight of adsorbent in

decolorization of dye from simulated wastewater.

3.2 CHEMICALS

i. Palm oil waste (collected from nearby palm oil plantation in Nibong Tebal).

ii. Congo Red (Sigma Aldrich Corp.).

3.3 APPARATUS AND EQUIPMENTS

NO. APPARATUS/EQUIPMENTS

1 Conical Flasks (250ml)

2 Volumetric Flasks (1000ml)

3 Volumetric Flasks (500ml)

4 Pipette

5 pH meter

6 UV/VIS Spectrophotometer

7 Orbital Shaker

8 Dryer Multi Point

9 Weight Container

19

3.4 ADSORBENT PREPARATION

Palm oil waste was collected from nearby palm oil plantation factory in Nibong

Tebal, Penang by the Department of Applied Sciences, UiTM Penang. It was dried

under sunlight until all the moisture has evaporated. The material was ground to

fine powder. The crush palm oil waste was then washed with water; the precipitated

was removed by hand before it is being dry using dryer multi point (model P3500) at

110°C. The processes to get a dry palm oil waste are illustrated in plate 3.1, 3.2

and 3.3 below. The raw was subjected to carbonization at 110°C for 3 days using

dryer multi point (see plate 3.4) under closed condition. The carbonized material

was taken out and being sieved by Auto Sieve Shaker (Model: D408 ENDECOTTS)

(see plate 3.5) to approximately 150 μm and the resulting material ready to be used

for adsorption studies. No other chemicals were used to treat the palm oil waste for

adsorption enhancements.

Plate 3.1 Raw material of Palm oil waste

Plate 3.2 Palm oil waste washed with water and removed the precipitate before

drying in multi point at 110°C

20

Plate 3.3 Final products after drying process

Plate 3.4 Dryer Multi Point

Plate 3.5 Auto Sieve Shaker D408 ENDECOTTS

21

3.5 PREPARATION OF ANIONIC DYE SOLUTIONS

The anionic dye, Congo red (CR) was manufactured by Sigma Aldrich Corporation,

Germany and supplied by Faculty of Chemical Engineering, UiTM Penang. The dye

was come with analytical grade and it was used without any further purification. It is

a hazardous dye and fully safety conditions were applied throughout the

experimental works. The stock solution was prepared by dissolving accurately

weighted dye in distilled water in the concentration of 500 mg/L. It was done by

weighting 0.5 g of Congo red (CR) on the top loading balance (Model X3-100) then

the weighted dye was dissolved in 1L of distilled water in a 1L Volumetric flask. The

solution was then properly agitated for favour dissolving distributions. The stock

solution was saved for dilution process with certain determined concentrations which

was obtained by successive dilutions. The dilution process was done in three

different samples where each sample contains of 10, 25 and 50 ml of stock solution

where each determined concentrations were added with 490, 475 and 450 ml of

distilled water respectively. The chemical formula of M1V1 = M2V2 has been applied

throughout the dilution process in order to get a correct value of respective desired

concentration. Each sample was then saved for further experimental works by

labeling each of the different concentrations.

3.6 PROCEDURE

Three main parameters that have been used throughout this work were the weight

of adsorbent, contact time and shaking speed. It was done by a certain procedures

that lead to the successive adsorption studies.

3.6.1 Weight of Adsorbent

To determine the effect of weight of adsorbent in the treatment of wastewater for

removal of Congo red (CR), three different amount of palm oil waste which are 0.5g,

1.0g, and 2.0g was introduced into 250ml conical flasks each containing 100ml of

stock solutions. The flasks were then shaken at room temperature using the orbital

shaker SK-600. Plate 3.6 shows the orbital shaker used to shaken the stock

solutions and palm oil waste.

22

Plate 3.6 Orbital Shaker SK-600

3.6.2 Contact Time

The aim of this experiment was to determine the optimum contact time (shaking

time) for Congo red removal. In order to assess the effect of contact time in the

removal of Congo red, the palm oil waste was tested with various predetermined

contact times. The set of three conical flasks consist of different weight of adsorbent

that were then shaken by the orbital shaker with 60, 180 and 300 minutes of contact

time for each set.

3.6.3 Shaking Speed

Throughout the present work, shaking speed was set to be constant at 150rpm with

all different weight of adsorbent. The samples were then brought to the

Environmental Laboratory for UV check. This has been done by using UV/VIS

Spectrophotometry (Shimadzu UV-160 A) to measure the adsorbance after shake

as illustrated in plate 3.7. The experiments were carried out in triplicate and being

averaged to get the consistency of results.

23

Plate 3.7 UV/VIS Spectrophotometry (Shimadzu UV-160 A)

3.7 ADSORPTION STUDIES

The dye solutions were prepared from stock solutions (500 mg/L) to desired

concentration. The adsorption experiments were carried out by a batch method.

100 mL of solution containing amount of palm oil waste and dye solution were taken

in a 250 mL conical flask. A different amount of adsorbent was then introduced with

4 sets of different volumetric flask. Each set contains 0, 0.5, 1.0 and 2.0 g of

adsorbents and agitated at constant speed of 150rpm at room temperature over a

period of time. The sets which contain with no adsorbents have not been shaking

and it is used for pH checking (see plate 3.8) and colour different observation. The

CR concentration of supernatant was measured after the treatment by using UV

spectrophotometer, at the maximum wavelength of Congo red at 500 nm

(λ = 500nm) (Shimadzu UV-160 A). Calibration curves were plotted between

absorbance and concentration of the standard dye solutions.

24

Plate 3.8 Delta 320 pH meter

The removal efficiency (E) of adsorbent on Congo red was defined as:

E (%) = [(C0 – Ci) / C0] x 100 3.1

Where E (%) is the removal efficiency of dye adsorbed per unit weight of palm oil

waste; C0 the initial concentration of CR (mg/L); Ci the concentration of CR in

solution at equilibrium time (mg/L).

Blank runs, with only the sorbate in 100 ml of distilled water, were

conducted simultaneously at similar conditions to account for colour changes

adsorbed by glass containers. The experimental parameters studied are adsorbed

amount (0.5, 1.0 and 2.0 g/100mL), contact time (60, 180 and 300 min), and initial

dye concentration (10, 25 and 50 mg/L).

25

CHAPTER 4

RESULTS AND DISCUSSIONS

4.1 PRELIMINARY RESULT

The preliminary result of the present work was observed by its color observation.

The color change of the simulated wastewater depicted the successfulness of the

work done.

4.1.1 Color Observation

Color observation is one of the vital parameter in determination of the experimental

success. Besides, by implementing the color observation, we can evaluate how far

the effectiveness and relevancy of the adsorbent that has been used. From the

present experiment, the color of simulated wastewater by the mixture of Congo red

with distilled water before and after treatment by the adsorbent presence was

observed and it showed that the color was clearer after the treatment rather than

before treatment (see plate 4.1). The bright red color of Congo red is depicting its

carcinogenic, toxic and mutagenic effect (Gregory et al., 1991; McKay et al., 1985).

The color changes show that the palm oil waste effective to be an adsorbent in

removing of dye from wastewater.

26

Plate 4.1 Comparison of color changes before (left) and after (right) treatment

4.2 EXPERIMENTAL RESULTS

This experiment was conducted in order to determine the effect of process

parameters which is shaking time, adsorbent dose and initial dye concentration.

The effect of pH could not be determined due to the time constraint factors. Three

experimental trial results of removal of Congo red by adsorption onto palm oil waste

with effect of process parameters were done. Average value of the triplicate trials

result was then calculated in order to get an average value. Percent of dye removal

was then finally calculated. The tabular data of the present experiment are shown in

the table 4.1, 4.2, 4.3 and 4.4.

27

Table 4.1 Tabular data of the first trial

CONCENTRATION,

mg/L

PALM OIL WASTE,

(g)

ABSORBANCE

1h 3h 5h

10

0.0 0.733 0.733 0.733

0.5 0.420 0.398 0.288

1.0 0.549 0.509 0.476

2.0 0.500 0.450 0.320

25

0.0 1.173 1.173 1.173

0.5 0.860 0.800 0.676

1.0 0.989 0.880 0.743

2.0 0.940 0.821 0.700

50

0.0 1.906 1.906 1.906

0.5 1.593 1.447 1.076

1.0 1.722 1.709 1.432

2.0 1.673 1.655 1.300

Table 4.2 Tabular data of the second trial

CONCENTRATION,

mg/L

PALM OIL WASTE,

(g)

ABSORBANCE

1h 3h 5h

10

0.0 0.733 0.733 0.733

0.5 0.397 0.300 0.288

1.0 0.553 0.511 0.496

2.0 0.501 0.449 0.211

25

0.0 1.173 1.173 1.173

0.5 0.780 0.700 0.654

1.0 0.845 0.811 0.543

2.0 0.913 0.875 0.361

50

0.0 1.906 1.906 1.906

0.5 1.300 1.223 1.200

1.0 1.488 1.421 1.361

2.0 1.329 1.275 1.087

28

Table 4.3 Tabular data of the third trial

CONCENTRATION,

mg/L

PALM OIL WASTE,

(g)

ABSORBANCE

1h 3h 5h

10

0.0 0.733 0.733 0.733

0.5 0.455 0.400 0.286

1.0 0.629 0.651 0.457

2.0 0.511 0.491 0.400

25

0.0 1.173 1.173 1.173

0.5 0.568 0.540 0.497

1.0 0.575 0.570 0.488

2.0 0.958 0.900 0.843

50

0.0 1.906 1.906 1.906

0.5 1.590 1.520 1.432

1.0 0.996 0.884 0.655

2.0 0.990 0.876 0.598

Table 4.4 Average to the triplicate trials

CONCENTRATION,

mg/L

PALM OIL WASTE,

(g)

ABSORBANCE

1h 3h 5h

10

0.0 0.733 0.733 0.733

0.5 0.424 0.375 0.257

1.0 0.577 0.398 0.352

2.0 0.504 0.380 0.334

25

0.0 1.173 1.173 1.173

0.5 0.736 0.614 0.463

1.0 0.797 0.703 0.497

2.0 0.937 0.845 0.510

50

0.0 1.906 1.906 1.906

0.5 1.319 1.197 0.896

1.0 1.402 1.203 0.901

2.0 1.564 1.241 1.031

29

To achieve the objective of this experiment which is to determine the effect

of process parameters on Congo red removal in simulated wastewater by using

adsorption, the experimental data that obtained was analyzed by constructing a

graph of percent of dye removal versus adsorbent dose which is the palm oil waste

for each set of experiments. The graph shows that the percent of dye removal

increased as the weight of palm oil waste increasing and the percent removal mostly

depicted removal of more than 30%. Even though the adsorbent that has been

used is palm oil waste instead of activated carbon, the results of dye removal is still

acceptable. This is support by an article by A.G Liew et al., (2005), which they had

found that about 36.9% of methyl red dye was removed by using 0.6 g/100ml of

sugarcane baggase as the adsorbent. The agricultural non-conventional adsorbents

was proved that it can be a good adsorbent to remove of dye from wastewater

instead of conventional adsorbent such as alum, ferric and chloric.

30

4.2.1 Effect of Contact Time

The variation of Congo red adsorbed with time is shown in Figure 4.2 below. It was

observed that with a fixed amount of palm oil waste, the amount of Congo red

adsorbed increases with time and then attained a constant value after 200 min. The

time to reach equilibrium conditions appears to be independent of initial Congo red

concentrations. As shown in Table 4.5, we can conclude that with a fixed amount of

palm oil waste, the amount of Congo red adsorbed increases with time. During the

experiment, maximum contact time of 300 min shows the efficiency of percent

removal of Congo red decrease. This happened as the aggregation of dye

molecules with the increase in contact time makes it almost impossible to diffuse

deeper into the adsorbent structure at highest energy sites (Indra Deo Mall et. al.,

2004).

The Graph of Percent of Dye Removal vs. Contact Time

0

20

40

60

80

100

0 50 100 150 200 250 300 350

Time (minute)

Per

cent

Dye

Rem

oval

(%)

0.5(g/100ml)

1(g/100ml)

2(g/100ml)

Figure 4.2 Effect of adsorbent dosage on removal of CR by palm oil waste

This aggregation negates the influence of contact time as the mesopores

get filled up and start offering resistance to diffusion of aggregated dye molecules in

the adsorbents. This factor also has been studied by Indra Deo Mall et al., (2004)

where they have extent the contact time up to 7 days and it was observed that the

Congo red removal by baggase fly ash was only increases by about 0.5% over

those that have been obtained for 240 min of contact time. This is the reason why

an insignificant enhancement in adsorption is effected as the number of contact time

increase. Since the difference in the adsorption values at 60 min and 300 min is

very small, the experiments were conducted for 300 min of contact time only. The

31

adsorption curve is single, smooth and continuous leading to saturation and

indicated the possible mono-layer coverage on the surface of adsorbents by the dye

coverage on the surface of adsorbents by the dye molecules (Wong and Yu, 1999;

Malik, 2003).

As we look from the graph, the lowest percent of removal of Congo red is

when 0.5 g of adsorbent is used. The percent adsorption increased and equilibrium

time decreased with increasing adsorbent doses. The adsorption increased from

33.2 to 83.9%, as the palm oil waste treated dose was increased from 0.5 g to 2.0 g

at equilibrium time (60 min). The maximum dye removal was achieved within 90-

120 min after which Congo red concentration in the test solution was almost

constant. Increase in the adsorption with adsorbent dose can be attributed to the

increase in adsorbent area and availability of more adsorption sites.

Table 4.5 Effect of adsorbent dose on the dye adsorption

Adsorbent dose,

(g)

Percent (%) dye removal with time (min)

60 min 180 min 300 min

0.5 33.2 35.1 37.9

1.0 61.4 62.3 64.6

2.0 83.9 84.5 92.1

32

4.2.2 Effect of Initial Concentration

The Graph of Percent of Dye Removal vs. Contact Time

0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350

Time (min)

Per

cen

t o

f R

emo

val (

%)

10(mg/L)

25(mg/L)

50(mg/L)

Figure 4.3 Removal of CR as a function of equilibrium time

The percentage of Congo red adsorption with varying amounts of palm oil waste is

presented in Figure 4.3 above. In general, the increase in adsorbent dosage

increased the percent removal of adsorbate. This is consistent with the expectation

that higher adsorbent dosages will result in more adsorption process as more pores

available to adsorb the contaminants. The graph shows the removal of Congo red

by palm oil waste at different adsorbent doses (0.5 – 2.0 g/100mL) for the dye

concentrations of 10, 25 and 50 mg/L at different time intervals of 60, 180 and 300

min. Results are shown in Table 4.6. It is evidence that the percent adsorption

efficiency of palm oil waste decreased with the increase in initial dye concentration

in the solution. The percent of dye uptake is 65.0% by the influence of initial

concentration of 10mg/L at 300 min.

After while the initial concentration was increased to 25mg/L, the percent of

dye uptake was decreased by 6.92% to 60.5% and the percent decrease of dye up

taken by initial concentration was increment by 18.46% to 53.0% of removal was

observed by the influence of 50mg/L of initial concentration. The graph is not

perfectly obeying the general where it should be. As we can see from the graph, for

concentration of 10 mg/L, for 180 contact time, the trend is decrease where the line

should be higher than 25 mg/L line. This might be due to some experimental error

that occurred. To be compared, the percent removal of dye with initial concentration

of 10 mg/L is the highest instead of 25 and 50 mg/L of initial concentration in the

33

solution. In the process of dye adsorption, initially dye molecules have to encounter

the boundry layer effect before diffusing from boundry layer film onto adsorbent

surface. This is followed by the diffusion of dye into the porous structure of the

adsorbent. This phenomenon will relatively take longer contact time. The graph of

dye uptake is a single, smooth and continuous curve leading to saturation,

suggesting the possible monolayer coverage of dye on the surface of the adsorbent

(Garg et al., 2004).

Table 4.6 Effect of Congo red concentration on the dye adsorption

Initial dye

concentration,

(mg/L)

Percent (%) dye removal with time (min)

60 min 180 min 300 min

10 42.1 48.9 65.0

25 37.3 47.7 60.5

50 30.8 37.2 53.0

34

CHAPTER 5

CONCLUSION AND RECOMMENDATIONS

5.1 SUMMARY AND CONCLUSION

This experiment was conducted to determine the effect of process parameters which

is contact time, weight of adsorbent and initial concentrations on removal of Congo

red from wastewater by using adsorption technique. Adsorbent that has been used

was palm oil waste as replacement of conventional method due to high in cost.

Palm oil waste is a common biomass waste material and easily available at

a small price. The removal of Congo red from simulated wastewater using a non-

conventional treatment of palm oil waste has been investigated under different

experimental conditions in batch mode basis. The adsorption of Congo red was

observed to be dependent on the adsorbent dose and Congo red concentration in

the wastewater. The results show that as the amount of the adsorbent was

increased, the percentage of dye removal increased accordingly. It was observed

that with a minimum at least of 30% efficiency of dye removal was established

during the present work that depicted the efficient of palm oil waste as the

adsorbent. Higher adsorption percentages were observed at lower concentrations

of Congo red. This study proved that palm oil waste is an attractive option for dye

removal from dilute industrial effluents. Even though the results obtained were not

favourly fits with the past study conducted, the trend can be considered to obey the

way it should be.

Experimental work that has been done showed that palm oil waste which

was used as an adsorbent was efficient in removing Congo red more than 30%.

The results of percentage dye removal versus weight of activated carbon showed

that the percentage of Congo red removal increasing as the weight of palm oil waste

increased for all parameters. This is due to the increase in adsorbent surface area.

35

Other parameter investigated which is contact time was also reported that

percentage of dye removal was increased with time and then it attained a constant

value after certain period of time. It might be due to the loosely attached molecule

that re-enter into the adsorbate and thus lowering the percentage of removal

efficiency of the dye. Aggregation of dye molecules with the increase in contact time

makes it almost impossible to diffuse deeper into the adsorbent structure at highest

energy sites (Indra Deo Mall et. al, 2004).

5.2 RECOMMENDATIONS / FUTURE WORK

From result of this experiment of Congo red removal from wastewater by using palm

oil waste as adsorbent, it is recommended to use adsorption isotherm models such

as Langmuir and Freundlich isotherm in order to determine the mathematical

relationships to describe the adsorption behavior of a particular adsorbent-adsorbate

combination. They help in calculating the adsorption capacity of material used.

Time constraint was the main hardship that has been faced due to the late

of chemical supplied. The study might be useful if the adsorbent could be treated

with other chemicals for an enhancement purposes. From the recent study, it was

observed that the adsorbent that has been treated with other chemicals along the

adsorption process can result with a higher percentage of dye removal. This could

be evidence from the study conducted by Liew Abdullah A.G. et. al, (2005) where

sulphuric acid treated sugarcane baggase showed a better performance compared

to untreated sugarcane in the percentage of methyl red.

It was difficult to analyses the effect of pH parameter on percentage of

Congo red removal onto palm oil waste due to the time constraint factors. The pH

effect study has got to be skipping as this might take more time to be done as the

presence of other chemicals is needed to treat the adsorbent in order to investigate

the effect of pH. Effect of initial dye concentration shows a good trend in term of

percentage of dye removal. It was evidenced that the percent adsorption efficiency

of palm oil waste decreased with the increase in initial dye concentration in the

solution. However, this might be improved if the palm oil waste can be treated with

other chemicals to act as the catalyst to the adsorbent to boost up the efficiency on

adsorption capacity.

36

In this experiment, investigation through the mechanism of adsorption and

the potential rate-controlling processes is not being made. Therefore, for future

studies, adsorption kinetics which is pseudo-first, pseudo-second order and the

intraparticle diffusion models are fully suggested to be made in order to analyze the

adsorption kinetics for all parameters investigate.

For more effective studies on carbon material uses as an adsorbent,

activated carbon is recommended to be part with. This is because activated carbon

might give more accurate value of removal percentage due to its large surface area

that makes it an effective adsorbent. There are slight errors occurred in this

experiment maybe due to improper weighting of adsorbent-adsorbate that makes

the results did not fits the trend where it should be. For that reason, accurate

measurement of adsorbent or adsorbate must be done in accurately to have a

correct and more precise reading of the dye removal.

37

REFERENCES

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sludge in a continuous packed bed: prediction of breakthrough curves.

Process Biochem. 39, pp. 599-613.

Allen, S.J., McKay, G., and Khader, K.Y.H. (1989) Intraparticle diffusion of a basic

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