Optimization of Biodiesel Production from Jatropha Oil (Jatropha curcas L.) using Response Surface Methodology

Abstract

The main purpose of this research was to develop a biodiesel production technique from Jatropha oil (Jatropha curcas). Special attention was paid to the optimization of alkali-catalyzed transesterification for converting fatty acid methyl ester (FAME). Jatropha oil contained 2.59 mg KOH/g of acid and a molecular weight of 900 g/mol with high oleic acid (41.70%) and linoleic acid (36.98%). A central composite design (CCD) technique was applied for the experimental design. There were 20 experiments involving the three investigated variables of methanol-to-oil molar ratio (0.95-11.50), sodium hydroxide (0.16-1.84% w/w) and reaction time (39.55-140.45 min). The data was statistically analyzed by the Design-Expert program to find the suitable model of % fatty acid methyl ester (% FAME) as a function of the three investigated variables. A full quadratic model was suggested by the program using response surface methodology (RSM) with an R² and adjusted R² of 97 and 94%, respectively. The optimum conditions for transesterification were a methanol-to-oil molar ratio of 6.00, 1.00% w/w sodium hydroxide and 90 min reaction time. The optimum condition obtained a FAME content of 99.87%. The resulting Jatropha biodiesel properties satisfied both the ASTMD 6751 and EN 14214 biodiesel standards. The production technique developed could be further applied in a pilot plant.