Use Of Palm Oil Fiber An Agricultural Waste For Removal Of Methylene Blue From Aqueous Solution_fairus

Fairus Muhamad Darus, Harnie Jamilah Hashim, Rusdin Laiman, dan Mohd Nizam Yusoff. 2005. Use Of Palm Oil Fiber, An Agricultural Waste For Removal Of Methylene Blue From Aqueous Solution. Dlm: Jamaluddin Jahi, Kadir Ariffin, Azahan Awang, Kadaruddin Aiyub & Muhammad Rizal Razman (Eds). Prosiding Seminar Kebangsaan Pengurusan Persekitaran 2005. 4 – 5 Julai 2005. ms 301 - 308. Bangi. UKM. ISBN: 983-2975-47-6

USE OF PALM OIL FIBER, AN AGRICULTURAL WASTE FOR REMOVAL OF METHYLENE BLUE FROM AQUEOUS SOLUTION Fairus Muhamad Darus, Harnie Jamilah Hashim, Rusdin Laiman and Mohd Nizam Yusoff Environmental Technology Programme Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam

Abstract Adsorption of dye is an alternative technology to remove colour from wastewater. Activated carbon prepared from low cost palm oil fiber has been utilized as the adsorbent for the removal of basic dyes from aqueous solution. A basic dye, Methylene Blue has been used as the adsorbate. Experiments were conducted at different pH, different adsorbent dose, different initial concentration of dye and different contact time. The most effective of color removal was optimum at pH 7 and the percentage removal increased with the increase in carbon dose. While the percentage removal decreased with increasing of initial dye concentration. The adsorption equilibrium for color reached at 90 minutes of contact time. The results indicated that palm oil fiber could be employed as low cost alternatives to commercial activated carbon in wastewater treatment for dye removal.

Abstrak Penjerapan warna adalah teknologi alternatif untuk menyahwarna dari air sisa buangan. Karbon teraktif yang dihasilkan daripada sabut kelapa sawit pada kos rendah telah dikenal pasti sebagai penjerap untuk menyahwarna pewarna beralkali dari larutan berair. Pewarna beralkali, Methylene Blue telah digunakan sebagai larutan. Kajian dibuat pada pH yang berbeza, sukatan karbon yang berbeza, nilai kepekatan warna pada permulaan kajian berbeza dan pada masa pertembungan yang berbeza. Penyahwarnaan pewarna yang efektif adalah pada pH 7 dan peratus penyahwarnaan meningkat dengan peningkatan sukatan karbon. Sementara itu peratus penyahwarnaan pewarna menurun dengan peningkatan kepekatan pewarna pada permulaan kajian. Keseimbangan Penjerapan untuk warna telah dikenal pasti pada minit ke 90. Keputusan menunjukkan sabut kelapa sawit boleh dijadikan alternatif kepada karbon teraktif yang boleh dikomersil bagi merawat air sisa buangan khususnya untuk penyahwarnaan pewarna.

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1. Introduction Water pollution is now emerging as a major problem in the developing world and its abatement has always been issued in our environmental concern today. The problem of removing pollutants from water and wastewater has grown with rapid industrialization. In Malaysia, 97 % of the effluent discharged is mainly from three industrial categories, which are food industry, chemical industry and textiles industry (Azira et al., 2004; Ong et al., 2004). Among various industrial processes, dyes from textile industries produce a large amount of colour effluent which is unacceptable under Malaysia environmental regulations besides other parameters such as COD, BOD, dissolved oxygen, total iron, and others (Tan et al., 2000). The discharging of dyes effluents into natural streams and rivers are causing severe problems, as dyes impart toxicity to aquatic life, thus damaging the aesthetic nature of the environment because dyes used in industry are mostly stable to light and oxidation, as well as resistant to aerobic digestion. Dyes and pigments are not commonly used in textile industries but also many other industries such as plastics, paper, food, cosmetics, paints, leather, art and craft, printing inks and rubber. The various treatment methods for the removal of colour and dye are coagulation using alum, lime, ferric sulfate, ferric chloride, chemical oxidation using chlorine and ozone, membrane separation processes, adsorption and so on. Among these methods, adsorption currently appears the best treatment in order to remove colour from wastewater (Walker et al., 1998; Chern et al., 2001; Namasivayam et al., 2001a; Yang et al., 2001; Annadurai et al., 2002a; Robinson et al., 2002b; Gupta et al., 2003; Janos et al., 2003; Rozada et al., 2003). Dyes and colour discharged into rivers that meant for public water supply may not meet the drinking water quality standards. Dyes and their degradation products may be carcinogen and toxic if these effluents are treated inefficiently before discharging to the rivers or streams, they could bring negative impact to human health (Kadirvelu et al., 2003; Pala et al., 2003). In this study, palm oil fiber has been chosen as activated carbon. By using this agricultural waste, it may reduce solid waste disposal problem and also minimize the cost of activated carbon production. The use of palm oil fiber for removing pollutants will benefit the environment. Contaminated streams and rivers will be cleaned and new market will be opened for the palm oil fiber. This study will provide useful information about the efficiency of activated carbon prepared from palm oil fiber in the adsorption of dyes from textile wastewater. 2. Methodology In this study, a physical chemical treatment was applied in order to remove the colour. Experimental variables considered were (i) different initial concentration of dye; (ii) pH; (iii) dose of adsorbent; and (iv) contact time between adsorbent and dye solution. 2.1 Preparation of activated carbon from palm oil fiber The raw material used for activated carbon (AC) preparation was palm oil fiber (POF). To manufacture the AC, dewatered POF was mixed with concentrated H2SO4 (17.5M) (1:2 v/w) and dried in air at room temperature for 24 hours. 300g of dried material was 302

put into an oven, heated at 180oC for 24 hours. The samples were then allowed to cool at room temperature in an inert atmosphere. The product resulting from the activation step was blend in order to form a granular AC and washed with 3M NaOH per 100 g of product. The carbon product then was vacuum-filtered through Whatman 2 V filter paper and washed repeatedly with distilled water to remove all traces of the acid and alkaline i.e until the pH of the rinsed water was constant. The product was wet-screed and dried at 80oC overnight. 2.2 Aqueous solution In preparation of aqueous solution, a stock solution of Methylene blue (MB) (1000 mg/l) was prepared and diluted to the required initial concentration. Adsorption experiments were carried out at room temperature (27±1 oC). 2.3 Adsorption experiments For adsorption analysis, a duplicate sample and control were prepared for further treatment studies. The initial and final concentration of MB was obtained by measuring at 663 nm using spectrophotometer. 100 ml of MB solution of known initial concentration was shaken at the constant agitation speed (200 rpm) with required dose of AC prepared from different weight of POF (0.2, 0.4, 0.8, 1.2, 1.6 and 2 g) from 30 to180 min of contact time in incubator. The initial pH of the solutions (pH 7.2) were adjusted to the required value (range: 3-9) by adding 1M NaOH or 1M H2SO4 solution. 2.4 Separation techniques For separation between adsorbent and solution, the sample was centrifuged at 200 rpm at predetermined times. After centrifugation, the samples were removed and its supernatant was measured by using UV-spectrophotometer. The final concentration was measured by using UV-spectrophotometer to determine the colour removed from synthetic wastewater. 2.5 Analysis of the data Data was analyzed by calculating the percentage removal of dye and the amount adsorbed (in mg/g) by using this following relationships: Percentage removal Amount adsorbed (qe)

= 100 (Ci . Cf) / Ci = (Ci . Cf) / m

where Ci and Cf initial and final concentration (in mg/L) of dye respectively, and m is the mass of activated carbon (in mg/L). Blank containing no dye was used for each series of experiments as controls. The average values of duplicates runs were obtained and analyzed. 3. Result and discussion 3.1 Effect of pH on dye removal in aqueous solution Although pore size distribution and the relative size of adsorbate have a significant effect on adsorption capacity, the chemical nature of the adsorbent also plays a major 303

role. In order to know the role of surface chemistry on the adsorption capacity of dyes, the effects of pH have been studied. The experiments have been carried out at different pH (pH 3 – 9) and different dye concentration (50, 70 and 100 mg/L) and constant carbon dosage of 2.0 g. The results are shown in Figure 1. The percentage of removal for dyes was optimum at pH 7 with 120 minutes contact time for three different dye concentrations. The lower adsorption of Methylene Blue, a cationic dye, at strong pH is probably due to the presence of excess H+ ions competing with the dye cation for the adsorption sites (Kannan et al., 2001; Annadurai et al., 2002b; Janos et al., 2003). As the pH of the system increases, the number of positively charged sites decreases and the number of negatively charged sites increases. The negatively charged sites favor the adsorption of dye cation due to electrostatic attraction. 50 mg/L

70 mg/L

100 mg/L

120 99.2

Amount Removal (%)

100 90.4

80

60

86.2

71.4 69.2 67.4

40

20

0 3

4

5

6

7

8

9

pH

Figure 1: Effect of pH on dye removal using AC prepared from POF (dose = 2 g, temp = 27 ± 1 oC, time: 120 min, particle size: < 105 µm)

3.2 Effect of different initial dye concentration The results in Figure 2 showed that the concentration of dyes decrease after treatment with AC prepared from POF. Removal of dye by adsorption using AC prepared from POF at 50 mg/L initial dye concentration was 78.6% and 99.4% for 1 and 2 g adsorbent dosage respectively. The amount of dye removed decreased when initial dye concentration increased to 100 mg/L with 54.8% and 84.5% for 1 and 2 g adsorbent dose respectively. The result showed the significant decrease on amount of dye removal when the initial dye concentration increased from 50 mg/L to 100 mg/L. Increase in the initial dye concentration of Methylene Blue decreased the percent removal of AC prepared from POF that remained constant after equilibrium time. 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). As the initial dye concentration is increased, the percent removal is lower. This is due to limitation of the adsorbent mass where the binding site of adsorbent/solute ratio is smaller (Azira et al., 2004). 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., 2002a; Garg et al., 2003). 304

1g

2g

120 99.4

Amount Removal (%)

100 84.5

80 78.6

60 54.8

40

20

0 50

60

70

80

90

100

Concentration (mg/L)

Figure 2: Effect of different initial dye concentration on dye removal using AC prepared from POF (pH = 7.2, temp = 27 ± 1 oC, time: 120 min, particle size: < 105 µm)

3.3 Effect of adsorbent dose and contact time The removal percentage increased when the AC prepared from POF dose was increased from (0.2-2.0 g/100 ml) at 50, 70 and 100 mg/L dye concentration (Figure 3). The removal percentage of dyes increased with the increasing in adsorbent dosage. At 2.0 g of adsorbent, a maximum removal of 99.8%, 92.4% and 86.4% was obtained for 50 mg/L, 70 mg/L and 100 mg/L respectively and a minimum removal of 70.2% for 50 mg/L, 70 mg/L and 100 mg/L dye concentration respectively. At 0.2 g of adsorbent a minimum removal of 70.2%, 50.2% and 32.3% was obtained for 50, 70 and 100 mg/L of dye concentration at constant pH of 7.2. The result showed a significant increase of amount dye removal in different adsorbent dosage (0.2 - 2.0 g). Varying the adsorbent mass may affect the porosity of the adsorbent suspension. A larger mass of adsorbent could adsorb larger amount of dyes due to the availability of more surface area of the adsorbent (Namasivayam et al., 1996; 2001a; 2001b). The increases in the adsorption with the dose can be attributed to increase surface area and the availability of more adsorption.

305

50 mg/L

70 mg/L

100 mg/L

120 99.8

100

Amount Removal (%)

92.4 86.4

80 70.2

60 50.2

40

32.2

20

0 0.2

0.4

0.8

1.2

1.6

2

Adsorbent Dose (g)

Figure 3: Effect of adsorbent dose on dye removal using AC prepared from POF (pH = 7.2, temp = 27 ± 1 oC, time: 120 min, particle size: < 105 µm)

The removal percentage increased with the increase of contact time and remains constant after the equilibrium time that was presented in Figure 4. Removal of dyes from AC prepared from POF increased rapidly in the beginning but then slowed down until the equilibrium time. The equilibrium time for the dyes MB with different initial concentration for 50, 70 and 100 mg/L were 90 min respectively. The result showed that the amount of dye removal remain constant after the equilibrium time. It shows that the removal of dyes from AC prepared from POF was increased with the increase in agitation and reached equilibrium after 90 min for the dye concentration of 50, 70 and 100 mg/L. Removal of dye by adsorption on AC prepared from POF increased rapidly in the beginning and then slowly decreased until the equilibrium time. 50 mg/L

70 mg/L

100 mg/L

110

Amount Removal (%)

105 99.4

100 96.6

95

92.8

90 89.1

85 81.1

80 75 73.4

70 30

60

90

120

150

180

t (min)

Figure 4: Effect of contact time on dye removal using AC prepared from POF (dose = 2.0 g, pH = 7.2, temp = 27 ± 1 oC, particle size: < 105 µm)

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4. Conclusion Methylene Blue is found to be adsorbed strongly on the surface of carbons. In overall, the adsorption can be influenced by many factors, such as adsorbent dose and particle size, different initial dye concentration, agitation speed, contact time, temperature, pH and ionic strength of the aqueous solution. Generally, the percent of removal increase with the increasing of pH, adsorbent dose, contact time and agitation speed. This study revealed that activated carbon from waste palm oil is an effective adsorbent for the removal of dyes in aqueous solution. Activated carbon (AC) prepared from palm oil fiber (POF) could also be employed as a low costs alternative for the removal of colour and dyes in water and wastewater, particularly for the removal of Methylene Blue. This treatment is economical as palm oil fiber is freely available in palm industries. References: Annadurai, Gurusamy., Juang, Ruey-Shin. & Lee. Duu-Jong. (2002a) Factorial design analysis for adsorption of dye on activated carbon beads incorporated with calcium alginate. Advances in Environmental Research 6: 191-198. Annadurai, Gurusamy., Juang, Ruey-Shin. & Lee, Duu-Jong. (2002b) Use of cellulosebased wastes for adsorption of dyes from aqueous solutions. Journal of Hazardous Materials B 92: 263-274. Azira, S., Wong, T. N., Robiah, Y. and Chuah, T. G. (2004) Adsorption of methylene blue onto palm kernel shell activated carbon. E Proceeding .Regional Conference For Young Chemists 2004. Universiti Sains Malaysia, Penang, Malaysia. Chern, J. M. & Wu, C. Y. (2001) Desorption of dye from activated carbon beds: effects of temperature, pH and alcohol. Water Resource, Vol 35, No 17: 4159- 4165. Gupta, V. K., Ali, I. & Mohan, D. (2003) Equilibrium uptake and sorption dynamics for the removal of a basic dye (basic red) using low-cost adsorbents. Journal of Colloid and Interface Science 265: 257-264. Janos, Pavel., Buchtova, Hana. & Ryznarova, Milena. (2003) Sorption of dyes from aqueous solutions onto fly ash. Water Research 37: 4938-4944. Kadirvelu, K., Kavipriya, M., Karthika, C., Radhika, M., Vennilamani, N. & Pattabhi, S. (2003) Utilization of various agricultural wastes for activated carbon preparation and application for the removal of dyes and metal ions from aqueous solutions. Bioresource Technology 87: 129-132. Kannan, N. & Sundaram, M. M. (2001) Kinetics and mechanism of removal of methylene blue by adsorption on various carbons . a comparative study. Dyes and Pigments 51: 25-40. Namasivayam, C., Muniasamy, N., Gayatri, K., Rani, M. & Ranganathan, K. (1996) Removal of dyes from aqueous solutions by cellulosic waste orange peel. Bioresource Technology 57: 37-43. 307

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