Optimization of biodiesel production by transesterification of vegetable oils using lipases

Enzymatic production of biodiesel by lipase transesterification of vegetable oils, requiring mild reaction conditions, tolerating water and free acids into the oil, facilitating the recovery of glycerol and fuel purification and producing low amounts of waste, overcomes the drawbacks of chemically catalyzed reactions. The main parameters influencing the yield of an enzymatic transesterification are amount of enzyme, alcohol/oil molar ratio, temperature, content of water and mixing intensity. In order to develop an efficient process the relation between the variables and yield must be known in detail. Monofactorial experimentation, practiced usually to determine all the independent parameters, is time consuming for complex processes, particularly when they interact with each other. Their designing requires an adequate experimental strategy - statistical experimental design, method that allows determination of the optimum set of experimental conditions. Response surface methodology proved to be a suitable technique to optimize lipase transesterification of vegetable oils. Its application both to some solvent-free and organic solvent systems is discussed.