Removal of Congo Red by Using Adsorption Onto Palm Oil Waste
Removal of Congo Red by Using Adsorption Onto Palm Oil Waste
Removal of Congo Red by Using Adsorption Onto Palm Oil Waste
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.”
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
iv
Accepted:
Signed :…………………………
Date :…………………………
Coordinator
Puan Siti Aminah Binti Mohd Ali
Faculty of Chemical Engineering
Universiti Teknologi MARA
Pulau Pinang
iv
ACKNOWLEDGEMENT
v
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
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
REFERENCES 38
LIST OF TABLES
viii
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
LIST OF FIGURES
ix
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
LIST OF PLATES
x
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
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.
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).
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:
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.
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.
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.
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.
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).
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).
8
2.2.3 Biological Treatment
9
Table 2.1: Different techniques used for dye decolorization
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.
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.
12
2.3.1 (b) Chemical 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).
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).
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).
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.
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).
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).
Figure 2.3 Activated carbon pore structures (Source: Impregnated Activated Carbon for
Environment Protection, 1997)
16
2.4.2 Non-Conventional Activated Carbon
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
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.
17
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.
CHAPTER 3
18
METHODOLOGY
3.2 CHEMICALS
i. Palm oil waste (collected from nearby palm oil plantation in Nibong Tebal).
ii. Congo Red (Sigma Aldrich Corp.).
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
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
19
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 3.2 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
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
21
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.
22
Plate 3.6 Orbital Shaker SK-600
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.
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)
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:
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
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.
26
Plate 4.1 Comparison of color changes before (left) and after (right) treatment
27
Table 4.1 Tabular data of the first trial
CONCENTRATION, PALM OIL WASTE, ABSORBANCE
mg/L (g)
1h 3h 5h
0.0 0.733 0.733 0.733
0.5 0.420 0.398 0.288
10
1.0 0.549 0.509 0.476
2.0 0.500 0.450 0.320
0.0 1.173 1.173 1.173
0.5 0.860 0.800 0.676
25
1.0 0.989 0.880 0.743
2.0 0.940 0.821 0.700
0.0 1.906 1.906 1.906
0.5 1.593 1.447 1.076
50
1.0 1.722 1.709 1.432
2.0 1.673 1.655 1.300
28
0.5 1.590 1.520 1.432
1.0 0.996 0.884 0.655
2.0 0.990 0.876 0.598
29
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).
30
T he Graph of Percent of Dye Removal vs. Contact T ime
100
Percent Dye Removal (%)
80
60 0.5(g/100ml)
1(g/100ml)
40 2(g/100ml)
20
0
0 50 100 150 200 250 300 350
T ime (minute)
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.
31
Table 4.5 Effect of adsorbent dose on the dye adsorption
Adsorbent dose, Percent (%) dye removal with time (min)
60 min 180 min 300 min
(g)
0.5 33.2 35.1 37.9
1.0 61.4 62.3 64.6
2.0 83.9 84.5 92.1
70
Percent of Removal (%)
60
50
10(mg/L)
40
25(mg/L)
30
50(mg/L)
20
10
0
0 50 100 150 200 250 300 350
Time (min)
32
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
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).
33
CHAPTER 5
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.
34
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.
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).
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.
35
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.
36
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