Study On Synthesis Of Epoxy Linseed Oil By Enzymatic Method

The application of plasticizer epoxidized vegetable oil is more and more extensive.At present,the industrial production of epoxidized vegetable oil uses chemical methods.The chemical method prepares peracetic acid by the reaction of acetic acid and hydrogen peroxide as a catalyst for epoxidation.This method corrodes equipment.And the waste water production is large.The use of enzymes as catalysts to catalyze the epoxidation of vegetable oil is environmentally friendly and has certain research prospects.However,there are still some problems to be solved in the industrial application of enzymatic epoxidation:(1)commercial lipase is expensive;(2)the epoxidation process uses organic solvents,such as toluene;(3)the use of hydrogen peroxide causes danger.In view of the problems existing in the current bioenzymatic synthesis of epoxidized vegetable oil,the epoxidation process of vegetable oil is improved through the following three aspects:(1)vegetable oil epoxidation reaction without solvent;(2)use safe and environmentally friendly deep eutectic solvent instead of toluene(3)The method of generating hydrogen peroxide in situ was introduced into the double-enzyme system to prepare epoxidized vegetable oil.The content is as follows:(1)The process of synthesizing epoxidized vegetable oil in solvent-free system was studied.The epoxidation process of vegetable oil in a solvent-free system was compared using commercial lipase and whole-cell bacterial enzyme as catalysts,respectively,and the reaction conditions were optimized.The bacterial enzyme activity was 12000 U/g,the addition amount was 30 %,the reaction temperature was 30 ℃,and the reaction time was 10 h.Under this condition,the epoxy conversion rate of linseed oil reaches 80.9%,and the epoxy value is 8.8.(2)The enzymatic synthesis of epoxidized vegetable oil in deep eutectic solvents(DES)system was developed,different types of eutectic solvents were screened,the effect of temperature on the viscosity of eutectic solvents was explored,and the temperature and addition ratio were optimized.Deep eutectic solvents were characterized.The results show that when the reaction temperature is 50 ℃,the application of choline chloride-glycerol eutectic solvent has higher epoxy value and conversion rate,which are 8.97 and82.48%,respectively.When the temperature drops,the epoxy value is 8.5,the conversion rate was 78.16%.(3)A new process for preparing epoxidized vegetable oil by double-enzyme coupling was constructed.The in situ generation of H2O2 required for the epoxidation of vegetable oil is realized through the process of glucose oxidase(GOD)catalyzing the oxidation of glucose to form gluconic acid and hydrogen peroxide(H2O2).The process conditions were optimized.10%(w/w)Novozym (?) 435,10%(w/w)GOD was added every 6 hours,the p H of phosphate buffer solution was 6.5,the ratio of oil to water was 1:1,and the concentration of phosphate buffer solution was 100 mmol/l.When the temperature was 40 ℃,the epoxy value of 8.67 reached the optimum value after 8 h of reaction,and the conversion rate was 79.72%.After 14 h of reaction,the yield of gluconic acid was 23 g/l.By transforming the synthesis process of epoxidized vegetable oil,a beneficial technical method is provided for the green synthesis method of epoxidized vegetable oil.