Dye Removal From Aqueous Solutio Using Palm Ash

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DYE REMOVAL FROM AQUEOUS SOLUTIO USIG PALM ASH AD COMMERCIAL ACTIVATED CARBO AS ADSORBET Fairus Muhamad Darus1, Ainorkhilah Mahmood2, Siti Mariam Sumari1 and Siti orlela Mohd Saad1 1

Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, MALAYSIA 2 Department of Applied Sciences, Universiti Teknologi MARA Pulau Pinang Email address of corresponding author: [email protected] ABSTRACT

Biosorption of dye using biomass is an alternative technology to remove colour from aqueous solution. Palm ash has been utilized as adsorbent for the removal of disperse dye from aqueous solution. In this study, Begacron Blue (disperse dye) has been used as the adsorbate. The effect of various experimental parameters, such as pH, initial concentration of dye, and agitation time were investigated. The percentage removal of dye increased with increased initial concentration of dye and pH for the same amount of adsorbent. The agitation times are not significance in this study. The most effective of color removal was 59.44% at pH 4 with contact time 120 minute. The data fit equally well for Langmuir and Freundlich. This study indicates that palm ash could be employed as a low cost alternative to commercial activated carbon. Keywords: Dye removal, Palm ash, Aqueous solution, Commercial activated carbon

1. ITRODUCTIO The shifted importance from raw material production to manufacturing especially in synthetic dyes such as textile, paper, food, cosmetics and pharmaceutical industries has detrimental effects to the environment due to the presence of a large number of contaminants like toxic organic residues, acids, bases and inorganic contaminants. Influents containing textile dyes are usually discharged in large quantities into natural water bodies on a daily basis (Meehan et al., 2000). Over 10,000 dyes with an annual production over 7 x 105 metric tons worldwide are commercially available and 5-10% of the dyestuffs are loss in industrial effluents (Ozfer et al., 2002). Hence this would eventually affect the water quality of receiving water bodies. Color removal from textile effluents has been given much attention in the last few years, not only because of its potential toxicity, but mainly due to its visibility problems (Marois et al., 1999). The presence of color can cause environmental issue because colour is the first contaminant to be recognized in water even at low concentration. The presence of color in a watercourse reduces light penetration because colour absorbs light. Dyes effluent gives a straightforward indication of water being polluted. The removal of dyes is of great concern since some dyes may contain heavy metals and their degradation products may be carcinogenic and toxic. Some dyes are more difficult to treat due to their synthetic origin, which contains complex aromatic compound. Many regulations have been enacted to regulate the effluent discharged by the industries. These regulations aim to control and limit several parameters in the effluent wastewater. Colour is one of the parameters concerned. For instance, the Environmental Quality (Sewage and Industrial Effluents) Regulation, 1979, limits the colour present in the final discharge by the industries to 10 Hazen for Standard A and 50 Hazen for Standard B (Environmental Quality Act, 1974) (Fairus et. al., 2007). Considerable research has been done on colour removal from industrial effluents to decrease their impact on the environment. Dye removal technologies include adsorption onto inorganic or organic matrices, decolourisation by photo-catalysis or photo-oxidation processes, microbiological decomposition, chemical oxidation, ozonation and coagulation can be used for removal of dyes and metal ions (Annadurai Paper number: 7210898

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C O N F E R E N C E ON S C I E N T I F I C & S O C I A L R E S E A R C H

et al., 2002). Among several chemical and physical methods, the adsorption onto activated carbon has been found to be superior to other techniques in water reuse methodology because of its capability for adsorbing a broad range of different types of adsorbents efficiently, and simplicity of design. In industries, conventional methods of colour removal come with high cost and are not very effective. The methods employed for treating dye wastewater include chemical precipitation; chemical coagulation, chemical oxidation, activated carbon sorption and biological treatment. These technologies however do not show significant effectiveness or economic advantage. Due to this problem, researches have increasingly to find locally available material for the removal of dye colours. Many sorbents based on low cost agriculture waste have utilization for dye sorption from wastewater like fly ash, palm fruit bunch and rice husk. A possible utilization of biomass resources is to turn this waste into carbon-based adsorbent. This application not only is useful for the removal of environmental organic pollutants but also for the reduction of greenhouse gas CO2 emission (Tsai et al., 2001). It has been proven in numerous studies that most agricultural by-products such as Indian Rosewood sawdust (Garg et al., 2003), coir pith (Namasivayam and Kavitha, 2002), fly ash (Wang et al., 2005), bagasses fly ash (Mall et al., 2006), and palm ash (Ahmad et al., 2007) are suitable raw materials for the production of low-cost activated carbon as alternative to commercial activated carbon. This is a great advantage as in some countries, agricultural by-product are considered as waste and did cause quite significant disposal problems. Their utilization as raw materials in producing activated carbon is a practical solution to clean up the environment in term of solid waste disposal. In this study, palm ash has been chosen as adsorbent. By using this agricultural waste, it may reduce and minimize the cost of activated carbon production. The availability of this source together with its characteristics has made palm ash a suitable choice to be an adsorbent. The result of this study is hoped to provide useful information on the efficiency of activated carbon prepared from palm ash for colour removal. 2. METHODOLOGY 2.1 Preparation palm ash as adsorbent The oil palm ash (OPA) were obtained from local oil palm factory and commercial activated carbon (CAC) were obtained from a local supplier. Both adsorbent was used in the experiment without any modification and pretreatment was used as an adsorbent. OPA and CAC was used as comparison adsorbent in this study. CAC with 2.5mm granular size was sieved to obtain particle size range at 0.20.5mm. 2.2 Aqueous solution 1000mg/L Stock solution of Begacron Blue dye supplied by Textile Laboratory (UiTM) was prepared and diluted to the required initial concentration (range: 50 - 250 mg/l) of dye solution. Adsorption experiments were carried out at room temperature (27 ± 1ºC). 2.3 Adsorption Experiment The initial and final concentration of each dye type was obtained by measuring at 594 nm for Begacron blue dye using spectrophotometer. Adsorption experiments were carried out by agitating 0.5g of the OPA in 100ml of dye solution of know initial concentration on a shaker operating at 200 rpm, respectively. The samples were withdrawn from the shaker at pre-determined time intervals (range: 5 - 240 min). The effect of pH was adjusted the pH of dye solutions using 1 M H2SO4 or 1 M NaOH solution (pH 2) where pH was measured using a pH meter (Hasnain et al., 2007). This procedure was repeated using CAC instead of OPA. Prior to the measurement of colour, the dye solutions were filtered through Whatman (no. 1) filter paper to exclude the adsorbent particles.

Paper number: 7210898

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2.4 Analysis of data The amount of dye adsorbed onto the adsorbent, qe (mg/g), was calculated by the following mass balance relationship: Percentage removal = 100 (Co – Ce) / Co ----------------- (1) Amount adsorbed (qe) = (Co – Ce) V/ W ------------------ (2) where Co and Ce are the initial and equilibrium state dye concentrations (mg/l), V is the volume of the solution and W is the mass of the adsorbent used (g). Blank containing no dye was used for each series of experiments as controls. The average values of dyes run were obtained and analyzed (Kannan and Sundaram., 2001). Two commonly used isotherms Langmuir and Freundlich were tested. The Langmuir isotherm and its linear form are represented by the following equations: (Ce/qe) = (1/Qob) + (Ce/Qo) ----------------- (3) where qe is the amount of adsorbate adsorbed per unit weight of adsorbent (mg/g), Qo limiting amount of adsorbate can be taken up per mass of adsorbent, b indicates the energy of adsorption (l/mg) and Ce is the equilibrium concentration of the adsorbate in solution (mg/l). The Freundlich isotherm and its linear form are represented by the following equations: Log qe = Log Kf + (1/n) log Ce -------------------- (4) where Kf is the Freundlich capacity factor and 1/n is the Freundlich intensity parameter. The characteristics of the Langmuir isotherm can be expressed by a dimensionless constant, the equilibrium parameter RL (Namasivayam et al., 2001b), which is defined by: RL = 1 / (1 + b Co) ------------------- (5) Where b is the Langmuir constant and Co is the initial dye concentration (mg/l). The value of RL indicates whether the isotherm is following the characteristic listed in Table 1:Table 1: The characteristic of value RL ature of adsorption process

RL Value

unfavourable

(RL > 1)

linear

(RL = 1)

favourable

(0 < RL<1)

irreversible

(RL = 0)

(Sources: Hasnain et al., 2007; Kannan & Sundaram., 2001)

3. RESULTS AD DISCUSSIOS 3.1 Effect of pH on dye removal in aqueous solution The effect of pH on the adsorption of dye by OPA was shown in Figure 1. For OPA the removal of dye was maximum at pH 4, then decreased at pH 5 and there after became unchanged until pH 12. The highest percentage of dye removal using OPA at pH 4 was 59.44% while the lowest percentage of dye removal was 51.77% at pH 2. The pattern of dye removal was similar for CAC, with maximum at pH 4 and then decreasingly and levelling off from pH 5. Paper number: 7210898

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Amount Dye Removal(%)

Oil Palm Ash

CAC

90 80 70 60 50 40 2

4

5

7

8

10

12

pH

Figure 1: Effect of pH on dye removal using oil palm ash and CAC Two possible mechanism of adsorption of dye on OPA may considered. First mechanism is the electrostatic interaction between the protonated groups of carbon and dye. Second mechanism is the chemical reaction between the adsorbates and the adsorbent (Namasivayam and Kavitha, 2002). At pH 2 a significantly high electrostatic attraction exits between the positively charged surface of the OPA and anionic dye. As the pH increases, for example to pH 5 the number of negatively charged sites decreases. A negatively charged surface sites on the OPA does not favour the adsorption of anions due to increase of electrostatic repulsion. The lower adsorption of dye at alkaline pH is due to the presence of excess OH- ions competing with the dye anions for the adsorption sites. At alkaline pH significant adsorption of the anionic dye on the adsorbent still occurred. This suggests that the second mechanism where the chemisorption, might be operative (Namasivayam and Kavitha, 2002; Hasnain et al., 2007). 3.2 Effect of different initial dye concentration in aqueous solution The effect of different initial concentration on dye removal dye using OPA and CAC was presented in Figure 2, which shows increasing efficiently of dye removal with the increased of initial dye concentration. Starting at 50mg/L with 76.93%, the amount of dye removed increased when the dye concentration increased to 100mg/L with dye removal of 88.14%. The removal of dye reached equilibrium after concentration 100mg/L. These results are comparable to other similar previous studies using the same material of adsorbent (Hasnain et. al., 2007). The process was found to be very rapid initially and a large amount of dye was removed within a few minutes. ## It is clear that the removal of dye was dependent on the concentration of dye (Namasivayam et al., 2001a; 2001b). The amount of dye adsorbed increased with increase in dye concentration and remained nearly constants after the equlibrium time. When the dye concentration increased it shows that the amount of adsorbent dose must be increased because dye concentration influenced the percentage of dye removal (Robinson et al., 2002; Garg et al., 2003).

Paper number: 7210898

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Oil Palm Ash

CAC

Amount Dye Removal(%)

100 95 90 85 80 75 70 50

100

150

200

250

Concentrations (ppm)

Figure 2: Effect of different initial dye concentration on dye removal using palm ash and CAC 3.3 Effect of agitation time of dye removal in aqueous solution The effect of agitation time in removal of dye by OPA and CAC was presented in Figure 3. The removal of dye adsorption on OPA and CAC was found to be rapid at the initial period of agitation time end then steadily decreased with the increase of agitation time. The highest percentage of dye removal for OPA at 240 minutes was 82.96% while the lowest percentage of dye removal at 10 minutes was 81.78%.

Amount Dye Removal(%)

Oil Palm Ash

CAC

87 86 85 84 83 82 81 80 79 10

20

30

60

90

120

180

240

Time(minute)

Figure 3:

Effect of agitation time on dye removal using palm ash and CAC

At the beginning, the dye ions were adsorbed by exterior surface of OPA, so the adsorption rate was fast. When the adsorption of the exterior surface reached saturation, the dye ions entered into the pores of the OPA particles and were adsorbed by the interior surface of the particle, This phenomenon take relatively long contact time. The time profile of dye uptake is a single, smooth and continous curve leading to saturation, suggesting also the possible monolayer coverage of dye on the surface of the OPA. A similar trend was reported for the adsorption of dyes by same material of adsorbent (Ahmad et. al., 2007). The dye is adsorbed to achieve adsorption equilibrium in about 1 h, although the data were measured 4 h. The time required to attain this state of equilibrium is termed equilibrium time, and the amount of dye adsorbed at the equilibrium time reflects the maximum adsorption capacity of the adsorbent under those operation conditions.

Paper number: 7210898

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3.4 Adsorption Isotherm Adsorption data for a wide range of adsorption concentration and agitation time have been treated by using Langmuir and Freundlich isotherms in order to find the adsorption capacity of OPA and commercial CAC. The linear plots of Langmuir isotherms and Freundlich isotherms for OPA and CAC can be referred to Figure 4 and 5. The sorption equilibrium data fit Langmuir equations with correlation coefficient values for OPA and CAC is 0.9487 and 0.9385 respectively. On the other hand, the sorption equilibrium data fit Freundlich equations with a correlation coefficient values of 0.9487 and 0.9385 for OPA & CAC respectively. Oil palm Ash

CAC

1.80

1.40

3.00

y = 0.1668x + 0.6609 2 R = 0.9487

Ce/qe (g/L)

Ce/qe (g/L)

1.60

1.20 1.00

2.40 1.80

y = 0.3673x + 0.85

1.20

0.80

2

R = 0.9385

0.60

0.60 6.77

17.69

28.38

40.09

58.52

10.20

Ce (mg/L)

24.60

37.95

65.59

87.95

Ce (mg/L)

(a)

(b)

Figure 4: Langmuir isotherms for the removal of dye by adsorption of OPA (a) and CAC (b). CAC

1.800

1.800

1.600

1.600

1.400

1.400

1.200

y = 0.1581x + 0.8511

1.000

log qe

log qe

Oil palm ash

1.200

y = 0.1471x + 0.8328

1.000

2

R = 0.9228

2

R = 0.9426

0.800

0.800 0.600

0.600 0.831

1.248

1.453

log Ce

1.603

1.767

1.009

1.391

1.579

1.817

1.944

log Ce

(a) (b) Figure 5: Freundlich isotherms for the removal of Begacron Blue by adsorption of oil palm ash and CAC.

The correlation coefficients Langmuir and Freundlich adsorption isotherms, were obtained by calculation using the experiment data. The result are summarised in Table 2 and 3.

Paper number: 7210898

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C O N F E R E N C E ON S C I E N T I F I C & S O C I A L R E S E A R C H

Table 2: Langmuir isotherm parameters Langmuir isotherm Qo

b

RL

Correlation Coefficient , (R2 )

Oil palm ash

5.995

0.735

0.252

0.9487

CAC

2.723

1.175

0.432

0.9385

Absorbent

Table 3: Freundlich isotherm parameters Freundlich isotherm Slope n (1/n)

Correlation Coefficient, (R2 )

Absorbent

Intercept (Kƒ)

Oil palm ash

0.8511

0.1581

6.3251

0.9426

CAC

0.8328

0.1471

6.7981

0.9228

The linear plots of Langmuir isotherms will determine whether the OPA can be used as low cost adsorbent by calculating the separation factor RL by using Langmuir equation (Eq. 4). The value of RL is 0.252, which falls in the range, 0 < RL < 1 as indicated in Table 1. Hence, the adsorption process is considered favorable as low cost adsorbents. According to Namasivayam et al., (2001a, 2001b, 2002), Tsai et al., (2001), and Rozada et al., (2003), Langmuir isotherms are based on the assumption that maximum adsorption corresponds to saturated monolayer of dye molecules on the adsorbent surface. The energy of adsorption is constant and there is no transmigration of adsorbate in the plane of the surface of activated carbons. The Freundlich isotherm describes equilibrium on a heterogeneous surface where energy of the adsorption was not equivalent for all adsorption sites, thus allowing multi-layer adsorption. The larger the value of adsorption capacity, Kf , the higher the adsorption. The more heterogeneous the surface will bring the 1/n value closer to zero (Tsai et al., 2001; Azira et al., 2004). Values of Kf and n were calculated from the slope and intercept of the Freundlich plots respectively. The magnitude of the exponent ‘n’ gives an indication of the favourability and Kf the capacity of the adsorbent/adsorbate system. Result from this experiment shows the n values ranging between 1 and 10, indicating beneficial adsorption. 4. COCLUSIOS The results of present study show oil palm ash (OPA) have suitable adsorption capacity in removing Begacron Blue dye (disperse dyes) from its aqueous solution. The adsorption is highly dependent on adsorbent dose, initial dye concentration, pH and contact time. Adsorption trends are found to follow both Freundlich and Langmuir isotherms. REFERECES Annadurai, Gurusamy., Juang, Ruey-Shin. & Lee. Duu-Jong. (2002) Factorial design analysis for adsorption of dye on activated carbon beads incorporated with calcium alginate. Advances in Environmental Research 6: 191-198. Ahmad, A. A., Hameed, B. H. & Aziz, N. (2007) Adsorption of direct dye on palm ash: kinetic and equilibrium modeling. J. Hazardous Materials. 141: 70-76. Anadurai, G., Juang, R. S. & Lee, D. J. (2002) Use of cellose-based waste for adsorption of dyes from aqueous solutions. J. Hazard Material. 92: 263-274.

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Paper number: 7210898