反胶束体系中脂肪酶催化乙酸甲酯与棉籽油合成生物柴油

在丁二酸二酯磺酸钠(AOT)反胶束体系中,采用游离脂肪酶催化棉籽油与乙酸甲酯反应制备生物柴油。考察了AOT浓度、水与AOT的质量比(ζ0)、脂肪酶用量、缓冲溶液pH、乙酸甲酯与棉籽油的摩尔比(r)、反应温度、摇床转速等因素对脂肪酶催化合成生物柴油的影响,并考察了脂肪酶的重复使用性能。经单因素实验及正交实验,得出优化的反应条件:AOT浓度40mmol/L,ζ0=7,脂肪酶用量10mg(溶液体积为2.5mL),缓冲溶液pH=7,r=3,反应温度35℃,摇床转速160r/min。在优化的反应条件下,产物脂肪酸甲酯的单程收率最高可达65.53%。酯交换制备生物柴油的影响因素大小依次为:缓冲溶液pH>反应温度>r>脂肪酶用量>AOT浓度>摇床转速>ζ0。与甲醇和碳酸二甲酯作为酰基受体相比,乙酸甲酯为酰基受体时脂肪酶的稳定性较好。

Synthesizing Biodiesel from Cottonseed Oil and Methyl Acetate with Lipase Catalyst in Reverse Micelle System

The synthesis of biodiesel from cottonseed oil and methyl acetate catalyzed by free lipase in bis(2-ethylhexyl) sulfosuccinate(AOT) reverse micellar systems was studied.The effects of the concentration of AOT,mass ratio of water to AOT(ζ0),lipase dosage,buffer pH,n(methyl acetate):n(cottonseed oil),reaction temperature and rotating speed on the synthesis were investigated.Single factor experiments and orthogonal experiments were carried out to optimize the reaction conditions.The yield of fatty acid methyl ester can reach 65.53% under the optimal conditions of ζ0 7,AOT concentration 40 mmol/L,lipase dosage 10 mg(solution volume 2.5 mL),buffer pH 7,n(dimethyl carbonate):n(cottonseed oil) 3,reaction temperature 35 ℃ and rotating speed 160 r/min.The effects of the conditions arrange in order of buffer pH>reaction temperature>n(methyl acetate):n(cottonseed oil)>lipase dosage> AOT concentration >rotating speed>ζ0.The stability of the lipase with methyl acetate as a receptor is better than those with methanol and dimethyl carbonate.