一种固定化脂肪酶的方法及其在生物柴油反应中的应用

发布时间：2018-03-07 12:40

  本文选题：生物柴油　切入点：脂肪酶　出处：《北京化工大学》2015年硕士论文　论文类型：学位论文

【摘要】：生物柴油是由植物或动物油脂(主要成分为甘油三酯)与醇类发生酯交换反应而生成的脂肪酸酯,是一种可再生的环保型的生物能源。传统的方法合成生物柴油能耗大,污染环境,且生产成本高,因此用脂肪酶催化合成生物柴油的方法获得广泛关注,它的优点在于条件温和,无污染,产物易分离等。脂肪酶是羧基酯水解酶,其天然底物为甘油酯,是一种重要的工业酶制剂,应用广泛,然而游离酶存在价格昂贵,反应后不易分离,难以实现工业化连续反应等诸多的弊端,所以本实验采用固定化技术减少这些弊端的产生,利用吸附法和包埋法相结合固定化实验室自制的Candida sp.99-125脂肪酶,用于生物柴油的催化合成。本文以硅藻土为载体对脂肪酶进行吸附,并考察得到吸附的最佳条件为：在30mLpH7.5的磷酸缓冲溶液中,酶与吸附剂硅藻土的质量比为1：3,其中,硅藻土采用添加剂(聚乙二醇6000、硫酸镁、吐温80、椰子油、卵磷脂)进行活化,吸附温度为25℃,吸附时间为3h,得到最优的包埋条件为：将1.5%的海藻酸钠溶液15mL,1%的明胶溶液15mL与之前吸附好的体系混合均匀后用注射器将其滴加入0.4mol/L的氯化钙溶液中形成凝胶状小球,干燥后保存。将所得的固定化酶用于催化月桂酸和正辛醇的反应,连续反应28批后酶活基本保持稳定。将固定化酶在4℃的条件下放置五个月,酶活降低小,储存稳定性很好。通过扫描电子显微镜对固定化酶的结构进行分析,固定化酶内部孔径多且均匀,网格结构发达,通过能谱分析固定化酶内部,酶与硅藻土以吸附的形式存在,分布均匀。将所得的固定化酶用于催化地沟油合成生物柴油的反应,单批反应转化率最高达到92%,连续反应十一批以后转化率仍保持在70%以上,与原始的发酵酶粉相比,固定化后的脂肪酶酶活和稳定性得到提高,而且便于工业化生产。
[Abstract]:Biodiesel is a fatty acid ester produced by the transesterification of plant or animal oils (mainly triglycerides) with alcohols. It is a renewable and environmentally friendly bio-energy source. Because of the pollution of the environment and the high cost of production, the method of using lipase to catalyze the synthesis of biodiesel has attracted wide attention. The advantages of lipase are mild conditions, no pollution, easy separation of products, etc. Lipase is a carboxyl ester hydrolase. Its natural substrate is glycerol ester, which is an important industrial enzyme preparation, which is widely used. However, free enzyme has many disadvantages, such as high price, difficult to separate after reaction, difficult to realize continuous industrial reaction, etc. Therefore, the immobilization technique was used to reduce the occurrence of these disadvantages, and the adsorption method and entrapment method were combined with the immobilized laboratory self-made Candida sp.99-125 lipase. In this paper, diatomite was used as carrier to adsorb lipase. The optimum conditions were as follows: the mass ratio of enzyme to adsorbent diatomite was 1: 3 in phosphate buffer solution of 30 mL pH 7.5. Diatomite was activated by additives (polyethylene glycol 6000, magnesium sulfate, Twain 80, coconut oil, lecithin) at 25 鈩，

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