Study on Free Lipase‐Catalyzed Ethanolysis for Biodiesel Preparation in an Oil/Water Biphasic System

Using free lipase as the catalyst for biodiesel production has drawn increasing attention in recent years due to its advantages of lower cost and faster reaction rate compared to immobilized lipase. Our previous study showed that free lipase NS81006 could effectively catalyze the methanolysis of renewable oil. Ethanol, derived from renewable biomass, has a greater potential for biodiesel production. In this paper, ethanol was explored for the first time as the acyl acceptor for free lipase‐mediated biodiesel preparation. The effect of stirring rate, water content, molar ratio of ethanol to oil and ethanol adding strategy was investigated systematically during the process of free lipase NS81006‐catalyzed ethanolysis. An ethyl ester yield of 90% was obtained under the optimized conditions. Further study showed that the free lipase could be repeatedly used by simple separation of the water phase from the oil phase and there was no obvious loss in lipase activity after five repeated uses.