Production of ethyl ester biodiesel from a tranesterification reaction of used vegetable oil and ethanol was carried out using a sodium methoxide catalyst. Response surface methodology (RSM) was applied to investigate the effect of experimental factors on the fatty acid ethyl ester (FAEE) conversion. The design of the experiment involved a 5-level-4-factor central composite design and 30 runs were used to achieve the optimum percentage FAEE conversion that was determined by 1H-NMR. The coefficient of determination (R2) for the regression equation was 86.49% and the probability value (p<0.05) demonstrated a very good fit for the regression model. The optimum conditions obtained from RSM were 4% v/v of catalyst, 35.61% v/v of ethanol-to-oil, at 43.70°C reaction temperature, and 75.45 min of reaction time. The produced ethyl ester biodiesel was further purified by wet washing compared with dry washing using ion exchange resin. The result showed that the purified biodiesel by wet washing met the EN standard but the dry washing out put did not but only for the acid value. The blending of 10% v/v of purified biodiesel obtained from dry washing with 90% v/v of petrodiesel could decrease the acid value to meet the EN standard.

Calcium methoxide obtained from quick lime is used as a solid catalyst in the transesterification reaction between palm stearin with methanol using tetrahydrofuran (THF) as co-solvent for biodiesel production. In this work, quick lime was used to prepare calcium oxide by heat treatment at the different temperatures, after that calcium oxide was further reacted with methanol to produce calcium methoxide catalyst. The properties of Calcium methoxide (Ca(OCH3)2) was characterized by XRD, SEM, BET, TGA, EDX and FTIR. The optimum conditions of biodiesel production were studied through response surface methodology and central composite design. The conversion of fatty acid methyl ester (FAME) was determined by proton nuclear magnetic resonance spectroscopy (1H-NMR). The results depicted that calcined quick lime at 800 °C for 3 h contained high calcium oxide content. The Ca(OCH3)2 catalyst prepared at 65 °C for 3 h gave high surface area and catalytic activity. The optimum conditions for biodiesel production were 2.33% w/w of catalyst, 1 : 9.39 of palm stearin to methanol molar ratio, 102 min of reaction time and 9.07% v/v based on methanol of THF co-solvent, the same condition gave 98.23% of FAME conversion.