Optimized synthesis of lipase-catalyzed biodiesel by Novozym 435

The ability of immobilized lipase from Candida antarctica (Novozym. 435) to catalyze the alcoholysis of canola oil and methanol was investigated. Response surface methodology (RSM) and five-level-five -factor central composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction time, temperature, enzyme concentration, substrate molar ratio of methanol to canola oil, and added water content on percentage weight conversion of canola oil methyl ester by alcoholysis. Reaction temperature and enzyme concentration were the most important variables. High temperature and superabundant methanol inhibited the ability of Novozym. 435 to catalyze the synthesis of biodiesel. Based on the analysis of ridge max, the optimum synthesis conditions were as follows: reaction time 12.4 h, temperature 38.0degreesC, enzyme concentration 42.3%, substrate molar ratio 3.5: 1, and added water 7.2%. The predicted value was 99.4% weight conversion, and the actual experimental value was 97.9% weight conversion. (C) 2004 Society of Chemical Industry.