Comparative Studies in the process of Biodiesel

Malaysian International Conference on Trends in Bioprocess Engineering (MICOTriBE),PWTC, Malaysia, 12-13 December 2009

BIODIESEL PRODUCTION FROM SLUDGE PALM OIL BY ULTRASONIC ENERGY Adeeb Hayyan1*, Md. Zahangir Alam1, Mohamed E.S. Mirghani1, Nassereldeen A. Kabbashi1, Noor Irma Nazashida Mohd Hakimi2, Yosri Mohd Siran2, Shawaluddin Tahiruddin2, Mohammed A. Al-Saadi1

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Bioenvironmental Engineering Research Unit (BERU), Department of Biotechnology Engineering ,Faculty of Engineering, International Islamic University Malaysia, P.O. BOX 10, Kuala Lumpur, 50728, Malaysia. E-mail: [email protected] 2

Processing & Engineering, R&D Center - Downstream, Sime Darby Research Sdn Bhd. Lot 2664 Jalan Pulau Carey, 42960 Pulau Carey, Kuala Langat, Selangor, Malaysia

ABSTRACT

The main challenges for biodiesel production are the cost of raw material (fats and oils) and the cost of processing. In this study free fatty acid (FFAs) of sludge palm oil has been converted to fatty acid methyl ester via acid-catalyzed reaction using ultrasonic energy. Batch esterification process of SPO was carried out to study the influence of sulfuric acid dosage (0.5, 1, 2% wt/wt), molar ratio of methanol to SPO (6:1, 10:1, 14:1), and temperature (50oC, 60oC, 70oC). The reduction of free fatty acids (FFAs) was measured at different sonication time from 30-300 min and the optimum time was determined. It is reasonable to conclude that the conversion of FFAs to fatty acid methyl ester by applying ultrasonic energy is related to long sonication time. The results showed that the FFA content of SPO reduced from 24.5% to less than 3 % using molar ratio 10:1, reaction temperature 50o C and 2% wt /wt sulfuric acid to SPO in 300 minutes sonication time. KEYWORDS: Biodiesel, Free fatty acids, Sludge palm oil, Ultrasonic.

1. INTRODUCTION Biodiesel becomes more attractive recently because of its environmental benefits and the fact that it is made from renewable resources. The remaining challenges are its cost and limited availability of fat and oil resources. There are two aspects of the cost of biodiesel, the costs of raw material (fats and oils) and the cost of processing [1]. The cost of raw materials accounts for 60% to 75% of the total cost of biodiesel fuel [2]. Currently, edible vegetable oils, such as palm oil, soybean, rapeseed and sunflower are the prevalent feedstocks for biodiesel production [3]. Exploring new methods to reduce the cost of raw material and the process are the main interest in resent biodiesel research. However, there are large amounts of low grade oils from palm oil industry that can be converted to biodiesel such as sludge palm oil (SPO). In Malaysia, SPO generated from palm oil mills reaches 200 ton/year. The use of SPO can lower the cost of biodiesel production 1


significantly, which makes SPO a highly potential alternative feedstock for biodiesel production. SPO usually contains high amounts of free fatty acids (FFAs) that cannot be converted to biodiesel using an alkaline catalyst [4]. In order to reduce the level of FFAs, esterification reaction using acid catalyst has been used by many studies to convert the FFAs to fatty acid methyl ester (FAME) [5]. The conventional approach to apply the esterification reaction was using mechanical stirring in a reactor. Recently ultrasonic energy has been used in biodiesel production in many studies as a new approach [6, 7, 8, 9]. The theory of using ultrasonic energy is ultrasonic irradiation causes cavitation of bubbles near the phase boundary between the alcohol and oil phases. As a result, micro fine bubbles are formed. The asymmetric collapse of the cavitation bubbles disrupts the phase boundary and impinging of the liquids creates micro jets, leading to intensive mixing of the system near the phase boundary [6]. In this work the esterification of SPO was carried out applying ultrasonic energy instead of mechanical stirring to produce biodiesel by converting FFAs to FAME via Sulphuric acid as acid catalyst in esterification reaction.

2. EXPERIMENTAL WORK 2.1 Raw materials and chemicals SPO was obtained from West Oil Mill, Carey Island, Selangor, Malaysia. SPO was stored in cool room at 4o C. Methyl alcohol anhydrous 99.8% was purchased from Mallinckrodt Chemicals USA, sulfuric acid 98% was purchased from Merck Sdn Bhd, Malaysia. 2.2 Procedures Sulfuric acid was added into the preheated SPO at different dosages (0.5, 1, 2% wt/wt) in the presence of methanol to reduce FFA of SPO by converting the FFA to FAME. Several batches of esterification process were carried out to study the influence of Sulfuric acid dosage (0.5, 1, 2% wt/wt), molar ratio of methanol to SPO (6:1, 10:1, 14:1), and reaction temperature (50, 60, 70o C). The effect of those parameters on FFA content at different sonication time (30, 60, 90, 180, 300 min) were determined. The ultrasonic reactions were performed using portable ultrasonic cleaner (Kodo Technical Research). After each experiment the reaction was stopped at specific time and the reaction mixture was allowed to settle in separating funnel 24 hours. After separation, FFA content has been measured to find the reduction of FFA content which indicates the conversion of FFA to FAME for each experiment. All experiments were performed in a closed Erlenmeyer type flask having 100 ml of SPO. 2.3 Analysis Analysis of FFAs content was tested according to AOCS methods 1980.Fatty acid composition of SPO was determined using GC/MS (Agilent Technologies 7890A), The capillary column was DB- wax 122-7032, with length of 30m, film thickness of 0.25µm and an internal diameter of 0.25mm. Helium was used as carrier gas with a flow rate of 36 cm/sec, measured at 50o C, The run time was 35 min. 1 µm of neat sample was diluted in hexane prior injection into GC. Table1 illustrates Fatty acid composition of SPO.

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Table 1: Fatty acid composition of SPO

Fatty acids Lauric acid Myristic acid Palmitic acid Stearic acid Oleic & Elaidic acid Linoelaidic acid Alpha-Linolenic acid Arachidic acid

Structure C12 C14 C16 C18 C18-1 C18-2 C18-3 C20

wt% 0.08 1.08 46.2 4.45 37.99 9.85 0.02 0.33

Free Fatty Acid%

3. RESULTS AND DISCUSSIONS 3.1 Effect of Sulphuric acid dosage in reduction of FFAs at different sonication time The results showed that Sulphuric acid was a very effective catalyst in esterification process. Figure 1 shows the effect of different dosage of Sulphuric acid on FFA content of SPO. The FFA content decreased from 24.5% to less than 3% in dosage 2% wt/wt sulphuric acid to SPO within 300 minutes sonication time. However based on the first minimum level of reduction of FFAs, 2% of Sulphuric acid gave the minimum value of FFAs, but 1% sulphuric acid gave an acceptable result after 300 minutes. The conversion of FFAs to Fatty acid methyl ester (FAME) using 0.5, 1, and 2% sulphuric acid to SPO in 300 minutes were 83.6, 85.1% and 88.6% respectively. 26 24 22 20 18 16 14 12 10 8 6 4 2 0

0.5% Sulphuric Acid 1% Sulphuric Acid 2% Sulphuric Acid Limits of FFA

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 Sonication Time min

Fig.1: Effect of dosages of Sulphuric acid on reduction of FFA content

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Free Fatty Acid%

3.2 Effect of molar ratio in reduction of FFAs at different sonication time Molar ratio is one of the important factors that affect the conversion of FFA to FAME, as well as the overall production cost of biodiesel. In this study the molar ratio of methanol to SPO was varied between 6:1 to 14:1 at different sonication time. Figure 2 describes the effect of molar ratio on the reduction of FFAs content of SPO. When molar ratio increased from 10:1 to 14:1 there is no significant change observed on reduction of FFA. Therefore 10:1 molar ratio was the optimum ratio to convert FFAs to FAME and to reduce the FFA content of SPO from 24.5% to around 3%, which is the limit of FFA for transesterification reaction. The conversion of FFAs to FAME using molar ratio 6:1, 10:1 and 14:1 methanol to SPO in 300 minutes were 81.6, 85.1% and 85.8% respectively. 26 24 22 20 18 16 14 12 10 8 6 4 2 0

6;1 10;1 14;1 Limits of FFA%

0

20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 Sonication Time min

Fig.2: Effect of molar ratio on reduction of FFA content

3.2 Effect of reaction temperature in reduction of FFAs at different sonication time In this study the reaction temperature was varied between 50o C to 70o C at different sonication time. Figure 3 presents the effect of reaction temperature on the reduction of FFAs content of SPO. The optimum reaction temperature was found to be 50o C and 70o C. The reason being is 50o C is below than the boiling point of methanol, which is 64.5o C. Chemically, at high temperature the SPO is less viscous (less solidify) and hence the reaction is enhanced due to easier mixing between SPO and methanol. The system was kept closed to avoid evaporation of methanol. At 70o C the rate of reaction becomes higher; hence the reaction completed in shorter time, at 180 min and gave acceptable results. In order to save the energy and to decrease the cost, 50o C is more acceptable because 70o C consumed more energy than 50o C. However, 50o C reduced the FFA content of SPO from 24.5% to 2.8% within 180 min sonication time and to 1.9 % within 300 min. The conversion of FFAs to FAME using reaction temperature 50o C, 60o C and 70o C in 300 minutes were 92%, 85.3% and 91.6%, respectively.

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Free Fatty Acid%

Malaysian International Conference on Trends in Bioprocess Engineering (MICOTriBE),PWTC, Malaysia, 12-13 December 2009 26 24 22 20 18 16 14 12 10 8 6 4 2 0

50 C 60 C 70 C Limits of FFA%

0

20

40

60

80 100 120 140 160 180 200 220 240 260 280 300 320 340 Sonication Time min

Fig.3: Effect of reaction temperature on reduction of FFA content

4. CONCLUSION In this study, the production of crude biodiesel from SPO having high FFA content was investigated. It was found that pretreatment step by esterification process using ultrasonic energy was very effective approach in biodiesel production. It can be concluded that optimum conditions to reduce FFAs content of SPO from 24.5 to less than 3% were 2% Sulphuric acid to SPO, 10:1 molar ratio, 50o C temperature in 300 minutes reaction time.

5. ACKNOWLEDGEMENTS The authors would like to thank the personnel of Processing & Engineering of Sime Darby Research Sdn Bhd and Sime Darby Biodiesel Sdn Bhd for supplying sludge palm oil and assisting in analysis work. We would like to thank the Department of Biotechnology Engineering, International Islamic University Malaysia (IIUM) for providing the facilities to undertake the research. 6. REFERENCES [1] [2] [3]

[4]

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