EXPERIMENTAL INVESTIGATION OF CASTOR OIL AS AN ALTERNATIVE FUEL FOR BIODIESEL

International Engineering Conference, Energy and Environment (ENCON 2014) Copyright c 2014 Editor(s), ENCON 2014. Published by Research Publishing. ISBN: 978-981-09-4587-9 :: doi: 10.3850/978-981-09-4587-9_P08 www.rpsonline.com.sg EXPERIMENTAL INVESTIGATION OF CASTOR OIL AS AN ALTERNATIVE FUEL FOR BIODIESEL A. S. Ahmed Corresponding author. Department of Mechanical and Manufacturing Engineering, Faculty of Engineering, Universiti Malaysia, Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia (phone: +6082583299; fax: +6082583410; E-mail: aasaleh@feng.unimas.my). S. Ismail and R. Rahman Faculty of Engineering, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia (E-mail: mailkool9l@yahoo.com; rmrezaur@feng.unimas.my). S. Hamdan Department of Mechanical and Manufacturing Engineering, Faculty of Engineering, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia (E-mail: hsinin@feng.unimas.my). In this study, the efficiency of biodiesel conversion from crude castor oil to castor biodiesel (CB) through transesterification method was investigated. The acid-base catalyzed transesterification under different reaction condition such as the molar ratio of alcohol and mass ratio of catalyst to oil was studied for optimum proportion to achieve highest yield of Castor biodiesel. The optimum condition for acid-base catalyzed transesterification was determined to be 0.22 oil/methanol (v/v) and 0.005 KOH/oil (v/v). The potential of CaCO 3 to be used as solid base catalyst for transesterification of castor oil was also investigated. Then the fuel properties of the produced castor biodiesel such as the calorific value, flash point and density were analyzed. Component analysis was carried out by using FT-IR. The diesel engine performance and emission test using different castor biodiesel blends were then conducted. B20 blend of castor biodiesel was proved to have the same engine power output as mineral diesel with lower average percentage of change in CO, PM and HC emissions compared to mineral diesel. Thus a B20 blend of castor biodiesel was a suitable alternative fuel for diesel. Keywords: biodiesel, transesterification, castor oil, diesel engine, emission T 1. INTRODUCTION he petroleum fuels play a very important role in the development of industrial growth, transportation, agricultural sector and to meet many other basic human needs of modern civilization. These fuels are limited and depleting day by day as the consumption is increasing very rapidly. Moreover, the production and use of petroleum fuel is alarming the environmental pollution problems to society. A global movement towards the generation of environment friendly renewable fuel is therefore under way to help meet increased energy needs. Biofuel had become one of the promising alternatives for fossil fuels. Biodiesel is among the potential biofuel that can easily being produced from vegetable oil. Biodiesel has become an interesting alternative fuel substitute over conventional diesel. Biodiesel is suitable to be used in diesel engine which is due to the similar properties to the conventional fossil diesel fuel in terms of power and torque and none or very minor of engine modification is required [1]. Moreover, the biodiesel has a few special features which are biodegradability and being much more environmentally friendly compared to the conventional fossil diesel and resulting in less environmental impact upon accidental release to the environment [2]. Biodiesel has many important technical advantages over conventional diesel such as inherent 53

54 Experimental Investigation of Castor Oil as an Alternative... lubricity, low toxicity, derivation from a renewable and domestic feedstock, superior flash point, negligible sulfur content and lower exhaust emissions [3]. Among the common vegetable oil used as a feedstock for the production of biodiesel are soybean, rapeseed,castor, jatropha and palm oil. Castor oil is one of the promising feedstock for biodiesel production. Castor oil is produced by means of extraction from castor bean harvested from castor plant. Castor oil is distinguished by its high content (over 85%) of ricinoleic acid. No other vegetable oil contains so high a proportion of fatty hydroxyacids. Castor oils have high molecular weight (298), low melting point (5 C) and very low solidification point ( 12 C to 18 C) that make it industrially useful, most of all for the highest and most stable viscosity of any vegetable oil [4]. Sixty years ago, castor oil was used for lamp oil, medicinal purposes and as a general industrial lubricant. Soon afterwards, chemical engineers were able to produce derivatives of the oil that were of even more benefit to man. The chemical structure of castor oil is of great interest because of the wide range of reactions it affords to the oleochemical industry and the unique chemicals that can be derived from it. These derivatives are considerably superior to petrochemical products since they are from renewable sources, bio-degradable and eco-friendly [5]. Recent research had concerned in using castor oil as a feedstock for biodiesel production. As castor oil is non-edible, there is no issue of competition with the food market and it can be the promising source of feedstock for biodiesel production. In this study, the acid-base catalyzed transesterification of castor oil are been carried out to determine the optimum reaction condition for the production of castor biodiesel. Then, the fuel properties such as density, flash point and calorific value are being analyzed and compared to conventional diesel. Engine performance and emission of castor biodiesel are being tested using various biodiesel blends and compared to the conventional diesel. 2. METHODOLOGY AND MATERIALS In this study, crude castor oil was extracted from castor bean by using mechanical and solvent extraction. The castor beans used was obtained from local company. The acid value of the crude castor oil was determined by titrimetry. The crude castor oil was converted into biodiesel by using acid-base catalyzed transesterification process. In this process, the first step acid catalyzed esterification was used to remove the high FFA in crude castor oil followed by base-catalyzed transesterification using potassium hydroxide (KOH) as a catalyst with methanol. In the second step, KOH was dissolved in CH 3 OH and the mixture is then heated up to 60 C. The methoxide formed after KOH was fully dissolved in CH 3 OH. On the other hand, the pre-treated oil in step 1 was then heated up to 60 C. The heated oil was mixed with the methoxide and the solution was shook at 250 rpm for 2 hours by using orbital shaker. The volume ratio of methanol to oil used was 1:4, 1:4.5 and 1:5.0 while the volume ratio of KOH catalyst to oil used was 0.0025:1, 0.0050:1 and 0.0075:1. The transesterification were repeated by using CaCO 3 as a catalyst to study the potential of CaCO 3 as solid base catalyst in transesterification of castor oil. The volume ratio of oil to methanol was kept constant at 0.22 oil/methanol (v/v) and the catalyst loading was varied by using 0.05g and 0.10g CaCO 3 [6]. After completing the process, the mixture was allowed to settle for 8 hours and then the mixture was poured into separatory funnel. The lower layer of glycerol, extra CH 3 OH, catalyst and other undesired product were removed. The upper layer of methyl ester or biodiesel was washed several times with desterilized water or warm water until the washing water become neutral. The biodiesel layer was filtered to remove impurities and then the biodiesel was heated up to 100 C. Biodiesel testing was carried out to compare the properties and performances of castor biodiesel and conventional diesel. The density was measured using Portable Density Meter DMA 35. Flash point was determined using Seta Multiflash Flash Point Tester, Universal

A. S. Ahmed et al. 55 Base Unit 34000-0. The calorificc value was determined using Parr 6400 Automatic Isoperibol Calorimeter. Emission analyses were carried out using Testo 350 XL Flue Gas Analyzer. Castor biodiesel and mineral diesel were tested using FT-IR Shimadzu Iraffinity-1 Spectrophotometer for component analysis. Diesel engine test was performed using Techno-mate, TNM-TDE-700 machine. The diesel engine testing was done 3 times with each blend of biodiesel. The blending percentage of biodiesel with diesel was set to 0%, 10%, 20%, 30%, and 40% and they are mentioned as B10, B20, B30, and B40. And important values such as motor speed, output voltage, output current and time for 20 ml fuel flow were recorded. The brake load for the diesel engine testing was fixed at120n and the radius of brake arm was set to 0.5m. 3. RESULTS AND DISCUSSIONS Measurement of FFA in Crude Castor Oil Measurement of FFA in crude castor oil is essential for the decision of the method of transesterification for biodiesel production. From the titration method, the acid value of FFA in crude castor oil was averagingg between the ranges of 20 23%, which is higher than 4%. The best conversion method was two-steps transesterification where FFA value is reduced at the first step (acid esterification) before proceeding to the second step (base transesterification). Catalyst to Oil Ratio For the first set of experiment, the amount of catalyst was set as the manipulated variable while the amount of methanol was set as the constant variable. From Table 1, it is observed that the highest yield of biodiesel was achieved with the amount of 0..10 g of KOH as catalyst that is 0.0050 KOH/oil (v/v). However, the biodiesel yield before and after the optimal amount of catalyst is noted to be lower. In the case of the catalyst shortage (0.05 g KOH), the biodiesel yield percentage is 60.0% as catalyst was exhausted beforee all the crude oil was converted to biodiesel while in the case of excess catalyst (0.15 g KOH), the yield percentage is at 55.0% as excess catalyst attributed to soap formation which will decrease the production of biodiesel [6]. Table 1: Biodiesel Yield Percentage for Different Amount of KOH (catalyst) Methanol to Oil Ratio For the second set of experiment, the amount of methanol was set as the manipulated variable while the amount of catalyst was set as the constant variable. From Table 2, it is observed that the highest yield of biodiesel was achieved with the 1:4.5 of oil-to-methanol

56 Experimental Investigation of Castor Oil as an Alternative... ratio. The biodiesel yield was also affected by the amount of methanol used as excess or shortage. The shortage of methanol used will decrease the yield of biodiesel significantly. Excess methanol (1:5.0 ratio) contributed to methanol wastage while shortage of methanol (1:4.0 ratio) attributed to the lacking of solution for the reaction to take place. Thus, it can be concluded that the optimal proportion of catalyst used to achieve the highest yield for homogeneous catalysed transesterification was 0.10 g of KOH per 20 ml of crude oil with 1:4.5 of oil-to-methanol ratio [6]. Table 2: Biodiesel Yield Percentage for Different Amount of Methanol CaCO 3 Catalyzed Transesterification From Table 3, it is observed that the usage of 0.05 g catalyst will achieve a yield of 40.0% while the usage of 0.10g of catalyst will achieve a yield of 45.0% per 20 ml of crude oil. This show that CaCo 3 have some capability to catalyst the transesterification reaction although the yield is lesser compared to KOH catalyst. The Ca + dissociated from CaCo 3 acts as electron acceptor that catalyze the formation of methoxide. The amounts of Ca + dissociated from CaCo 3 are directly correlated with the yield of methyl ester produced in the transesterification process [6]. Table 3: Biodiesel Yield Percentage for Different Amount of CaCO3 (catalyst) FTIR Analysis In the infrared spectrum of castor biodiesel Figure 1(a), the FTIR spectrum of castor biodiesel showed the alkane C H bond which lies on the wave numbers from 2800 cm 1 to 3000 cm 1 and 1350cm 1 to 1480 cm 1.Thus, it can be confirmed that both conventional diesel and biodiesel had the same functional group of C H (Figure 3(b)). However, the conventional diesel had no oxygen group, whereas biodiesel showed oxygen functional group such as C O and C=O at 400 cm 1 to 1500 cm 1 [18]. Therefore, the biodiesel with the existence of oxygen could be promoted cleaner and complete combustion.on the other hand, the conventional diesel withoutt any oxygen produced more black smoke and incomplete combustion during burning.

A. S. Ahmed et al. 57 Figure 1 FTIR spectrum of (a) castor biodiesel and (b) conventional diesel. Density, calorific value and flash point of crude castor oil, castor biodiesel and conventional diesel Density value must be maintained within tolerable limits to allow optimal air to fuel ratios for complete combustion [7]. For diesel, the standard range for density value is 848 kg/m 3. For biodiesel, the standard for density value is in the range of 870 900 kg/m 3. For crude castor oil, the density value is in the range of 956 963 kg/m 3. As observed from Table 4, the density for conventional diesel, castor biodiesel and crude castor oil are 841 kg/m 3, 921 kg/m 3 and 950 kg/m 3. It is observed that in comparison to the standards, conventional diesel and crude castor oil conforms to the range while castor biodiesel is sighted to be slightly higher than that of the standard. Higher value of density for biodiesel is contributed by the structural differences in the constituent of fatty acids of castor oil [8]. High density biodiesel is not favourable as it can lead to incomplete combustion and particulate matter emissions [9]. However, this problem can be solved by blending biodiesel with mineral diesel. From Table 5, it was observed that conventional diesel has the highest calorific value followed by crude castor oil and castor biodiesel with the calorific value of 44.803 MJ/kg, 38.130 MJ/kg and 37.908 MJ/kg.. The calorific value for castor biodiesel is slightly lower than that of the conventional diesel, where more amounts of biodiesel is needed to produce the same thermal energy as conventional diesel. Biodiesel has lower calorific value as its composition comprised of additional oxygen functional group compared to that of the composition of diesel, meaning that the differences in the constituent contributes to lower calorific value [10]. Flash point is the temperature that indicates the overall flammability hazards in the presence of air; higher flash point makes for safe handling and storage of biodiesel [11]. The flash point values for conventional diesel, castor biodiesel and crude castor oil are 75.0ºC, 130.0ºC and 230.0ºC respectively. From table 6, it was observed that crude castor oil has the highest value of flash point followed by castor biodiesel and conventional diesel. Castor biodiesel has higher flash point value over conventional diesel as biodiesel are more viscous compared to mineral diesel. Flash point was positively correlated with the viscosity of diesel. The higher the viscosity, the higher the boiling point and thus cause higher flash point. Other than that, diesel has branches and lower molecular weight components which lead to a reduction of flash point [12]. The high flash points of biodiesel make it suitable to be used as alternative to conventional diesel.

58 Experimental Investigation of Castor Oil as an Alternative... Table 4: The Density Value for Crude Castor Oil, Castor Biodiesel and Conventional Diesel Table 5: The Calorific Value of Crude Castor Oil, Castor Biodiesel and Conventional Diesel Table 6: The Flash Point for Crude Castor Oil, Castor Biodiesel and Conventional Diesel Engine Performance Table 7 shows the calculation results based on the data collected from diesel engine testing which is ranged from B0 to B40. It is observed that the brake horse power, engine power output, and mechanical efficiency are decreasing while the biodiesel blend ratio is increasing. However, the specific fuel consumption increased differently while the biodiesel blend ratio increased. Nevertheless, the engine power output, specific fuel consumption, and mechanical efficiency for every biodiesel blend are plotted into a graph for ease of comparison. Based on Figure 2, it is shown that the castor biodiesel blending percentage is inversely correlated to the engine power output. In other words, the engine power output decreased while the castor biodiesel blending percentage increased. The percentage of decrement for B10, B20, B30, and B40 relative to B0 is 0.03%, 0.04%, 0.05%, and 0.06%, respectively. From the calculated decrement percentage, it is analyzed that the reduction in engine power output of biodiesel blends is insignificant when compared to the conventional diesel, B0. However, it can be concluded that the low energy content of biodiesel per volume results in the low engine power output. From Figure 4, it can be observed that the specific fuel consumption is directly correlated to the castor biodiesel blending percentage. In other words, the specific fuel consumption increased when the castor biodiesel blending percentage increased. The increment of the specific consumption of B10, B20, B30, and B40 relative to B0 is 3.59%, 3.96%, 4.68%, and 6.23%, respectively. From the increment percentage,it can be spotted that the B40 has the highest SFC value and it consumes more fuel to produce 1 KW of power when compared to conventional diesel (B0). The higher SFC of those higher percentage blends ratio is due to the fact that the biodiesel has lower calorific value than the conventional diesel [20]. Furthermore, higher containments of oxygen in biodiesel are also the cause of the lower calorific value. Despite the better combustion of biodiesel compared to the conventional diesel, the oxygen in biodiesel takes up space in the

A. S. Ahmed et al. 59 blend and slightly increases the fuel consumption rate. Thus, higher oxygen content in biodiesel leads to the low calorific value of biodiesel. On the other hand, the mechanical efficiency is decreasing with the increasing of castor biodiesel blending percentage which is shown in Figure 3. The decrement percentage of mechanical efficiency for B10, B20, B30, and B40 relative to B0 is 0.085%, 0.085%, 0.163%, and 0.241%, respectively. From the decrement percentages that were calculated, they obviously show that the reduction in mechanical efficiency of castor biodiesel blends is insignificant. However, the lower mechanical efficiency of biodiesel is mainly due to the low volatility and high density of ester which affects the automization of the fuel and thus leads to poor combustion [13],[14]. Table 7:Diesel engine performance for different blends of castor biodiesel. Figure 2: Engine power output versus castor biodiesel blending percentage Figure 3: Mechanical efficiency versus castor biodiesel blending Percentage

60 Experimental Investigation of Castor Oil as an Alternative... Figure 4: Specific fuel consumption versus castor biodiesel blending percentage. Table 8: The percentage difference for different biodiesel Blends relative to conventional diesel, B0 Emission Analysis. From table 8 below, it was observed that all the components for emission gas analysis is lower for biodiesel except for NOx. Lower CO emission and lower SO 2 for biodiesel were due to the additional oxygen content in biodiesel, which improved the combustion in the cylinders of diesel engine [30]. Higher NOx emission for biodiesel is due to the oxygen concentration in biodiesel causing the formation of NOx in the emission gas [30]. Thus castor biodiesel emitted cleaner gas emissions than conventional diesel and more complete combustion. These properties make biodiesel suitable to be used as an alternative to conventional diesel or as a blend to lower the emission of conventional diesel. Table 9: The Emission Analysis for Conventional Diesel and Castor Biodiesel 4. CONCLUSION As a conclusion, the optimum operating parameter for acid-base catalyzed transesterification of castor oil was achieved by using methanol in the proportion of 0.22 oil/methanol (v/v) and KOH catalyst in the proportions of 0.005 KOH/oil (v/v). CaCO3 showed ability to acts as solid base catalyst for transesterification of triglycerides. The additional content of oxygen in castor biodiesel promote complete combustion in diesel engine thus lead to lower emissions.the high flash point of castor biodiesel make it safe for handling and storage. The insignificant change in reduction of mechanical efficiency and power output of castor biodiesel compared to conventional diesel make it suitable to be used in diesel engine. B20 blend of castor biodiesel was proved to have the same engine power output as mineral diesel. Thus, castor biodiesel is a suitable alternative fuel for diesel.

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