Pretreatment of waste oil and biodiesel preparation catalyzed by immobilized lipase

摘要

As a new kind of environment-friendly renewable energy, the high cost of raw materials limits the application of biodiesel. Producing biodiesel from waste oil could effectively reduce its material cost and the environmental pollution caused by waste oil. The complex composition of waste oil could lead to catalyst poisoning. In order to meet the raw material requirements of biodiesel production, the oxidation of hydrogen peroxide combined with the adsorption of activated white soil and carbon was investigated in this paper. The treatment process was optimized as follows: the waste oil was bleached with 5% hydrogen peroxide based on the oil weight for 30 min at 60°C, then was treated for 20 min at 70°C with 5% mixed adsorbent (the ratio of active carbon and bentonite was 1:1 ) based on the oil weight. The biodiesel was then catalyzed by immobilized lipase at 0.2 g/mL packing density in cyclic reactors at 40°C for 12 h with 0.6 mL/min flow rate. The study showed that two-step processing could improve the quality of waste oil significantly and meet the needs of biodiesel producing. A 90% conversion rate could be reached through the transesterification reaction catalyzed by immobilized lipase. Further refining was needed for the product because the acid value of biodiesel was slightly high.