Preparation Of New Immobilized Lipase And Optimization Of Production Biodiesel Process

Compared with conventional petrochemical diesel, biodiesel is a new type of alternative energy sources with two outstanding advantages of the renewable nature and environmental friendliness. In this article, the immobilization of lipase and process of biodiesel production are investigated.The immobilization of neutrophil lipase on diatomine, attapulgite and nano-silica dioxide was studied, respectively. The effects of the lipase quantity, immobilization time and temperature on activity of immobilized lipase were also researched.Diatomine as carrier, when the lipase quantity for 33374U·g-1, temperature 35℃, pH 7.5 and treating for 4h, the activity of immobilized lipase was approximately 5833U·g-1. Optimum reactive temperature and pH of immobilized lipase increased from free lipase 40℃to 50℃, and from 7 to 7.5, respectively. Thermal stability of immobilized lipase was improved. After immobilized lipase utilized for eight times, the relative activity was below 50%.Nano-silica dioxide as carrier, when the lipase quantity for 28300U·g-1, temperature 45℃, pH7.5, treating for 10h, the activity of immobilized lipase was approximately 3867U·g-1. Optimum reactive temperature and pH of immobilized lipase increased from free lipase 40℃to 45℃, and reduced from 7 to 5.5, respectively. Thermal and pH stability of immobilized lipase was greatly improved. After immobilized lipase utilized for eight times, the relative activity was over 75%.Attapulgite as carrier, when the lipase quantity for 25900U·g-1, temperature 25℃, pH7.5, treating for 5h, the activity of immobilized lipase was approximately 2800U·g-1. Optimum reactive temperature and pH of immobilized lipase reduced from free lipase 40℃to 30℃, and increased from 7 to 7.5, respectively. Thermal and pH stability of immobilized lipase was greatly improved. After immobilized lipase utilized for eight times, the relative activity was below 50%.A self-designed circulation reactor was developed to carry out the transesterification between waste oil and methanol on immobilized lipase catalyst. To 40g waste oil as the benchmark, the result showed that: when the temperature at 50℃, molar ratio of oil to ethanol 1:3, immobilized lipase weight 4g, 24g hexane, the reaction time of 8h, the conversion ratio of the reaction system could be up to 67.7%.