Co-immobilization of Candida rugosa and Rhyzopus oryzae lipases and biodiesel production

Candida rugosa lipase and Ryzopus oryzae lipase were simultaneously immobilized on silica gel following enzyme pretreatment. The factors affecting the co-immobilization process, such as reaction time and enzyme ratio, were investigated. Biodiesel was then produced by using the co-immobilized enzyme matrix. A batch system was employed with stepwise methanol feeding, and the continuous process involved a packed-bed reactor. Under optimal immobilization conditions, the activity was approximately 16,000 U/g center dot matrix. When co-immobilized enzyme was used with optimized stepwise methanol feeding, conversion of biodiesel reached about 99% at 3 h and was maintained at a level of over 90% for about 30 reuses.