Analysis of immobilized Candida rugosa lipase catalyzed preparation of biodiesel from rapeseed soapstock

Refined vegetable oils are the predominant feedstocks for the production of biodiesel. However, their relatively high costs render the resulting fuels unable to compete with petroleum-derived fuel. Response surface methodology (RSM) analysis of immobilized Candida rugosa lipase (CRL) on chitosan catalyzed preparation of biodiesel from rapeseed soapstock with methanol was carried out. Methanol substrate molar ratio, enzyme amount, water content and reaction temperature were four important parameters employed. RSM analysis showed good correspondence between experimental and predicted values. It was found that the most effective parameter was water content, which was in good agreement with the experimental value. The coefficient of determination (R-2) for the model was 92.86%. Probability value (P < 0.0001) demonstrated a very high significance for the regression model. Methyl conversion of 63.6% was obtained when optimum conditions of immobilized lipase catalyzed for biodiesel production were methanol substrate molar ratio of 4:1, enzyme amount of 8%, water content of 6% and reaction temperature of 45 degrees C. Methyl ester content was above 95% after molecular distillation process. (C) 2008 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.