Process Optimization of Ethyl Ester Biodiesel Production from Used Vegetable Oil under Sodium Methoxide Catalyst and its Purification by Ion Exchange Resin

Abstract

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.