Physico-chemical properties of biodiesel produced from Jatropha Curcas oil and fossil diesel

Transcription

1 Journal of Microbiology and Biotechnology Research Scholars Research Library J. Microbiol. Biotech. Res., 2011, 1 (1): ( Physico-chemical properties of biodiesel produced from Jatropha Curcas oil and fossil diesel Adebayo G.B, Ameen O.M and Abass L.T Chemistry Department, University of Ilorin, Ilorin ABSTRACT The production of biodiesel from the chemically extracted oil of Jatropha curcas has been carried out. The oil yield of Jatropha seed and the biodiesel output of the oil were studied in order to know the productivity of the oil. The physico-chemical properties of the biodiesel produced were evaluated and compared with that of fossil diesel. The physico-chemical properties assessed includes, specific gravity, density, flash point, kinematic viscosity (40 0 C), sulfated ash, carbon residue, and iodine value. The results revealed significant differences between the phyico-chemical properties of biodiesel from that of fossil diesel. Key words: Jatropha curcas, fuel, biodiesel, jatropha oil, INTRODUCTION Biofuel is a nonpolluting, locally available, accessible, sustainable, and reliable fuel obtained from renewable sources. The fractions of biomass that have been used and are still enjoying renewed attention as feedstock for production of liquid biofuels are from agricultural sources, like: lipids, simple sugars and polysaccharides sources. Biodiesel refers to vegetable oil or animal fat-based diesel fuel consisting of alkyl (methyl, propyl, or ethyl) esters obtained by chemical reaction of the lipids (vegetable oil, animal fat) with an alcohol. Biodiesel is a clean burning alternative fuel to fossil diesel. It is produced from domestically grown renewable resources. Chemically, most biodiesel consist of alkyl esters instead of the alkanes and aromatic hydrocarbons of petroleum derived diesel [1, 2]. Petroleum diesel, also called petrodiesel or fossil diesel is produced from the fractional distillation of crude oil between C (392 0 F) and C (662 0 F) at atmospheric pressure, Available online at 12

2 resulting in a mixture of carbon chains that typically contains between 8 and 21 carbon atoms per molecule [3]. However, recent research findings have indicated that biodiesel has combustion properties very similar to petrodiesel, including combustion energy and cetane ratings [1, 4]. The drought resistant Jatropha plant which is known as physic plant is found growing on uncultivated land in most parts of Africa and could be used as hedge plant. The plant is cherished for its medicinal value and the cake can be used as livestock feed if properly processed. Jatropha is a genus of approximately 175 succulent plants, shrubs and trees (some are deciduous, like Jatropha curcas L.) from the family Euphorbiaceae. Jatropha is nature to Central America [5], and has becomes naturalized in many tropical and subtropical areas, including India, Africa, and North America. The hardy Jatropha is resistant to drought and pests, and produces seeds containing % oil [6]. The cake of Jatropha seeds after oil extraction could be considered for energy production [7]. The plant is considered as the best source of biofuel production among the various plants based fuel resources, [8]. It has been reported that this underutilized biofuel plant will help in meeting the challenges of global biofuel demand (37 billion gallons) by 2016 [9]. Currently, Nigerian government has shown great interest in Jatropha and other biofuel plants. The aim of the government is to gradually reduce the nation s dependency on imported gasoline, reduce environmental pollutions as well as create commercially viable industry that can precipitate domestic job [10]. Hence this study aimed at quantify the percentage oil yield and biodiesel output of the oil of Jatropha Curcas seed grown in Kwara state, Nigeria and compare its physico-chemical properties with that of fossil diesel obtained in the locality. MATERIALS AND METHODS Collection, purification and preparation of Jatropha curcas seed The Jatropha curcas fruits were collected around Tanke in Ilorin and Omu aran both in Kwara State, Nigeria. The fruits were dried, dehulled to obtain the seed, the seed was separated from the seed coat and dried, undesired impurities were removed by hand-picking. The seed was prepared for extraction by grinding using a laboratory mortar and pestle to. The bulk of the oil was extracted using by soaking the grinded seed in a container with petroleum ether and left for 3 days, the extraction process was repeated 3 times for proper extraction. The fossil diesel used was purchase at Mobil Filling Station, Taiwo Road, Ilorin, Kwara State. Conversion of Jatropha curcas oil to biodiesel Preparation The bench scale trans-esterification reaction to produce the biodiesel was carried out following the modified method of Benjamin et al [11]. 450 ml of the oil was pour into the reactor and heated to 45 0 C to improve the oil s mixability with the alcohol. This catalyst concentration level was achieved by dissolving 4.1g of potassium hydroxide (KOH) in 100 ml of the alcohol and the mixture was stirred for twenty minutes to form potassium 13

3 alkoxide. The resulting solution was added to the oil in the reactor and the entire content was brought to a temperature of 55 0 C and then held at this temperature for an hour. The reactions product mixtures were allowed to separate into phases by standing for eight hours in a separating funnel so as to separate glycerol from the biodiesel. 5 ml of acetic acid was added to the biodiesel followed by washing with water to and was allowed to stand for eight hours in a separating funnel. The denser soapy mixture was carefully drained from the bottom of the separating funnel leaving behind the biodiesel. The biodiesel obtained was dried in an oven at 100 C for 1 hr and the volume determined. Physico-chemical analysis Values The specific gravity and density were both determined using the density bottle and was estimated using the equations below The flash point, kinematic viscosity, sulfated ash content and the carbon residue analysis were carried out at LUBCON Nigeria Ltd. The flash point was determined by the method of ASTM D93 using the Pensky-Martens closed cup tester, the Kinematic Viscosity at 40 0 C was measured following the ASTM D445 method using a calibrated Viscometer with a calibration constant of , the Sulfated Ash content was determined according to the ASTM D847 method and the carbon residue was measured using the ASTM D524 method. The iodine value was determined following the procedure of ASTM D1959. RESULTS AND DISCUSSION The percentage oil yield of Jatropha curcas seed and biodiesel gotten from the oil are 39.7 and 80.2 respectively. The oil yield was in agreement with 30-40% of earlier reports but lower than 60-80% reported by Belewu et al (2010). However, in the report of Belewu et al, [4], n-hexane was used as against the petroleum ether used in this work. The use of n-hexane may be preferable since it gives a higher yield. The biodiesel yield of the oil is also low compared to that which was specified in a literature [12]. This was reported to be 98% when a base catalysed mechanism is used. This could be due to the formation of soap which was so prominent during the conversion process. Table 1 presents the result of the physicochemical properties of the biodiesel produced by transesterification of oil extracted from Jatropha curcas and fossil diesel. 14

4 Table 1: Physico-Chemical Parameters Of Biodiesel And Fossil Diesel S/N Parameters Biodiesel Fossil diesel 1. Specific gravity Density 0.876g/cm g/cm 3 3. Flash point C 70 0 C 4. Kinematics viscosity (40 0 C) 4.8cts 3.6cts 5. Sulfated ash 0.06% 0.2% 6. Carbon residue 0.2% 0.7% 7. Iodine value From the result, it could be observed that the specific gravity of Biodiesel was in agreement with 0.88 obtained by Belewu et al, [4], and 0.88 in other report [9], however, the specific gravity of biodiesel is higher compared to that of fossil diesel (0.841). The density obtained for the biodiesel (0.876 g/cm 3 ) was in agreement with the specified value reported [13], which range from to 0.90 for biodiesel, and also in agreement with reported by Belewu et al, (2010). While a value of g/cm 3 obtained for the density of diesel fuel is lower than the specified standard of g/cm 3, [13]. The flash point of Biodiesel C is in agreement with specified standard [13], and also similar to ASTM and EN specification of biodiesel but lower compared to C reported by Belewu et al [4]. For diesel fuel, the flash point gotten is also in the agreement with the standard specified [13]. Flash point helps to monitor the safe handling and storage of fuel. The higher the flash point the safer the fuel and vice versa. The flash point of Biodiesel is higher than that of fossil diesel; therefore it could be said that Biodiesel is safer to handle than fossil diesel. The kinematic viscosity of Biodiesel 4.8 cts is in agreement with the manufacturer standard given [13], and also falls within the ASTM and EN limit of biodiesel. But lower compared to 9.60 cts reported by Belewu et al, [4]. The kinematic viscosity of fossil diesel 3.6 cts is in agreement with that specified [13]. The viscosity of biodiesel is higher compared to that of fossil diesel the implication is that biodiesel will have lubricating effect in engines which will be an added advantage to the users, since it will reduce wear and tear in the engine. The value of sulfated Ash obtained for biodiesel 0.06 is slightly higher compared to the standard specified 0.02% max [14]. However the value is lower than that obtained for diesel fuel 0.2%. The Ash content is a measure of the amount of metal contained in the fuel. From the result in table 4, it shows that fossil diesel contains more metal compound than the biodiesel. During the burning of the fuels, Biodiesel burnt with very low smoke compared to that of fossil diesel which burnt with heavy smoke. This implies that biodiesel emissions from exhaust of vehicles will help reduce the pollution introduced to the atmosphere compared to that of fossil diesel. The carbon residue of the biodiesel 0.2% was higher compared to 0.050max documented [14]. This could be due to the contaminant which might have entered the sample during the heating to evaporate the oil. The carbon residue of the diesel fuel from table 4 is higher compared to biodiesel. This implies that diesel fuels will form a higher deposits compared to that of biodiesel in engines. 15

5 The result of iodine value of biodiesel revealed a higher value compared with that of fossil diesel. Iodine value is used to measure the chemical stability property of substance against oxidation and the higher the iodine value the higher the number of double bond and hence lesser stability. This shows that the fossil diesel is more stable compared to the Biodiesel. However, the double bonds in biodiesel helps attract oxygen to the compound, and aid proper burning of biodiesel over fossil diesel. CONCLUSION This study has shown that most of the properties evaluated for the biodiesel conform to the ASTM and EN standard values. It could be concluded from this study that the biodiesel produced from Jatropha curcas oil is a potential replacement for fossil diesel while the production and effective usage of biodiesel will help to reduce the cost of protecting the atmosphere from the hazards in using fossil diesel and hence will boost the economy of the country. REFRENCES [1] P. T. Vasudevan and M. Briggs (2008) J Ind Microbiol Biotechnol, 35: [2] G. El Diwani, N. K. Attia, S. I. Hawash (2009), International Journal of Environmental Science and Technology, Vol. 6, No. 2, pp [3] Chris Collins (2007), Methods in Biotechnology 23: Humana Press. ISBN [4] Belewu M.A., Adekola F.A., Adebayo G.B., Ameen O.M., Mohameed N.O., Olaniyan A.M., Adekola O.F., and Musa A.K. Int. J. Biol. Chem. Sci. 4(2): [5] Fairless D. (2007). Nature 449 (7163): doi: /449652a. PMID [6] Achten WMJ, Mathijs E, Verchot L, Sjngh VP, Aerts R, Muys B, Biofuel, Bioproducts, and Biorefining 1(4), DOI: /bbb39 the Jatropha archives. [7] Jongschaap REE, Blesgraaf RAR, Boogard TA, Van Loo EN, Savenije HHG. Proc Nat Acad Sci USA 106(35). [8] Tint TK, Mya M World Academy of science, Engineering and technology; [9] Centre for jatropha promotion and biodiesel, [10] Federal Government of Nigeria Policy on Biofuel, Federal Republic of Nigeria official Gazette on Nigeria Biofuel policy and Incentives Fellows P. (1997). [11] Benjamin I.Ugheoke, David O. Patrick, Haruna M. Kefas, Emmanuel O. Onche (2007), Leonardo Journal of Science, 10: [12] [13] Manufacture of fuel standard comparism table, [14] American standard for testing and materials (ASTM D) for petroleum product. 16