Immobilization Of Lipase On Corn Cob And Catalyzing Synthesis Of Biodiesel

Lipase is a kind of enzyme having many catalytic functions, which is widely used in oil processing, food industry, pharmaceutical industry, daily chemical industry and so on. As the energy supply is becoming nervous gradually, the use of lipase in producing biodiesel has been a topic of wide concern. So far there are many problems to solve in producing biodiesel by lipase, such as:Expensive lipase increases the cost of production of biodiesel; The most used animal and vegetable oils to create biodiesel are edible oil, which must reduce the amount of people cooking oil; The carrier for lipase immobilization is expensive and fabrication process of it is complex. So research a new cheap technique producing biodiesel by lipase, it is beneficial for environmental protection, economic efficiency and the development of society.In this paper kibbling corncob was modified; Lipase was immobilized on the modified corncob carrier; Properties of immobilized lipase were detected; Then the immobilized lipase was used to catalyze non-edible oil cornus wilsoniana wanaer oil and methanol to biodiesel. The main results were taken as follows:1. The kibbling corncob was immersed in saturated potassium hydroxide and 2% citric acid for 24 hour; Then THAM was deemed to have better activation compared to glutaraldehyde, CMC, dimethyl adipimidate dihydrochloride; At last activating agent concentration, activation time and activation temperature were optimized by single factor and response surface methodology, and the best values of factors were:activating agent concentration 6.96%, activation time 3.63 hour, activation temperature 59.85℃. 2. The immobilization conditions enzyme solution/carrier, buffer solution pH,immobilization time and temperature were investigated by single-factor test, then four factors at three different levels were devised through Box-Behnken, and test data was statistic analysed by sofrware Statistica 6.0, which concluded the best immobilization conditions enzyme solution/carrierll.9, buffer solution pH6.7, immobilization time 9.6 hour and temperature 37℃. Under the best conditions mean immobilization lipase activity 1798 U/g of three parallel experiments was got. 3. Properties of immobilized lipase were detected, and the results showed that theoptimum water content was 6%; the good reaction temperature was 40～50℃; the best reaction pH was 6; the immobilization lipase activity could keep primary 60%, when immobilization lipase was in 70℃for 5 hour; if the immobilization lipase was deposed in 4℃refrigerator for 6 months, it could keep 90% of original activity; when it was in different organic solvent for 1 hour, the activity would lost seriously in ethanol or methanol, but the immobilization lipase could keep high activity in other organic solvent.4. When the immobilized lipase was used to catalyze cornus wilsoniana wanaer oil and methanol to biodiesel, biodiesel conversion rate would be high under these transforming conditions:substrate was emulsified for 12 hour and immobilization lipase was soaked in cornus wilsoniana wanaer oil for 6 hour in advance; hexane was added in transformation system and the addition was 5 times mole of cornus wilsoniana wanaer oil; the best mole rate of methanol and oil was 4, and methanol was added in 3 portions; the addition of immobilization lipase was 25 percent of cornus wilsoniana wanaer oil in mass ratio; water addition was 6 percent of immobilization lipase; reaction temperature was 40-50℃; reaction time was 25 hour. The activity half-life period was 500 hour. Biodiesel was composed by methyl linoleate, methyl palmitate, methyl oleate, methylarachidate, methyl stearate and so on.