本文選題：生物柴油　切入點：脂肪酶　出處：《北京化工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：生物柴油是由植物或動物油脂(主要成分為甘油三酯)與醇類發(fā)生酯交換反應(yīng)而生成的脂肪酸酯,是一種可再生的環(huán)保型的生物能源。傳統(tǒng)的方法合成生物柴油能耗大,污染環(huán)境,且生產(chǎn)成本高,因此用脂肪酶催化合成生物柴油的方法獲得廣泛關(guān)注,它的優(yōu)點在于條件溫和,無污染,產(chǎn)物易分離等。脂肪酶是羧基酯水解酶,其天然底物為甘油酯,是一種重要的工業(yè)酶制劑,應(yīng)用廣泛,然而游離酶存在價格昂貴,反應(yīng)后不易分離,難以實現(xiàn)工業(yè)化連續(xù)反應(yīng)等諸多的弊端,所以本實驗采用固定化技術(shù)減少這些弊端的產(chǎn)生,利用吸附法和包埋法相結(jié)合固定化實驗室自制的Candida sp.99-125脂肪酶,用于生物柴油的催化合成。本文以硅藻土為載體對脂肪酶進行吸附,并考察得到吸附的最佳條件為：在30mLpH7.5的磷酸緩沖溶液中,酶與吸附劑硅藻土的質(zhì)量比為1：3,其中,硅藻土采用添加劑(聚乙二醇6000、硫酸鎂、吐溫80、椰子油、卵磷脂)進行活化,吸附溫度為25℃,吸附時間為3h,得到最優(yōu)的包埋條件為：將1.5%的海藻酸鈉溶液15mL,1%的明膠溶液15mL與之前吸附好的體系混合均勻后用注射器將其滴加入0.4mol/L的氯化鈣溶液中形成凝膠狀小球,干燥后保存。將所得的固定化酶用于催化月桂酸和正辛醇的反應(yīng),連續(xù)反應(yīng)28批后酶活基本保持穩(wěn)定。將固定化酶在4℃的條件下放置五個月,酶活降低小,儲存穩(wěn)定性很好。通過掃描電子顯微鏡對固定化酶的結(jié)構(gòu)進行分析,固定化酶內(nèi)部孔徑多且均勻,網(wǎng)格結(jié)構(gòu)發(fā)達,通過能譜分析固定化酶內(nèi)部,酶與硅藻土以吸附的形式存在,分布均勻。將所得的固定化酶用于催化地溝油合成生物柴油的反應(yīng),單批反應(yīng)轉(zhuǎn)化率最高達到92%,連續(xù)反應(yīng)十一批以后轉(zhuǎn)化率仍保持在70%以上,與原始的發(fā)酵酶粉相比,固定化后的脂肪酶酶活和穩(wěn)定性得到提高,而且便于工業(yè)化生產(chǎn)。
[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，

本文編號：1579335