脂肪酶固定化及催化酯化反应

本研究报道了利用吸附法和化学键合法将白地霉脂肪酶固定化于五种载体上，用吸附法固定化的脂肪酶保持了高的活性。在有机溶剂中，固定化酶催化了长链脂肪酸与醇的酯化反应，酯化率可达９４％。固定化过程并未改变脂肪酶的选择性。固定化脂肪酶可重复使用。     

固定化脂肪酶催化废油合成生物柴油

研究了固定化假丝酵母99-125脂肪酶在有溶剂的体系下催化废油合成生物柴油过程中,油醇摩尔比、有机溶剂性质、底物浓度、体系含水量、甲醇流加等因素对反应过程的影响.研究结果表明,在最佳实验条件下,反应转化率最高可达92％,酶的使用寿命可达7批以上.     

多孔玻璃珠固定化脂肪酶及其催化合成生物柴油

以多孔玻璃珠为载体,采用共价法对假丝酵母99-125脂肪酶进行了固定,对比了固定化酶与游离酶的最适反应温度、pH值以及热稳定性.并以所制备的固定化酶为催化剂,在微水体系中利用菜籽油合成生物柴油,考察了溶剂量、体系水含量、甲醇等因素对固定化酶催化性能的影响,研究了固定化酶的操作稳定性.     

固定酶法催化合成生物柴油Ⅰ.大孔树脂固定化脂肪酶的制备

研究了用于生物柴油酶催化的大孔树脂固定化脂肪酶的制备过程,考察和优化了脂肪酶固定化方法及条件。结果表明,采用大孔树脂D3520作载体,以载体涂布法固定化脂肪酶的最适固定化条件为:酶用量为酶∶树脂=0.16∶1(质量比),吸附时间1~3 h,pH值范围为9.0~9.4,固定化温度40℃。酶活力可达91.49 U/g,酶活回收率约为54%。     

固定化脂肪酶催化酯交换制备生物柴油的研究进展

生物酶法生产生物柴油具有化学催化法不可比拟的优越性,是工业化生产的发展方向。介绍了固定化脂肪酶在催化油脂酯交换制备生物柴油方面的应用,对影响酯交换反应的脂肪酶源、底物摩尔比率、酰基受体、水含量、反应温度、副产物等因素进行了综述。     

脂肪酶催化非食用植物油制备生物柴油的过程优化

以麻疯树油、亚麻油、乌柏油为原料油,采用固定化脂肪酶Lipozyme TL IM,在3.0 g油、1 mL正己烷、醇油摩尔比为3.5∶1、固定化酶质量为油质量20%的条件下进行生物柴油的制备,通过脂肪酸甲酯产率和组成分析,以考察生物柴油制备的影响因素,进行反应时间优化.结果表明,酶的催化作用对脂肪酸组分不存在选择性,且...     

离子液体在脂肪酶催化合成生物柴油中的应用发展趋势

从固定化和非水介质两方面介绍了脂肪酶催化合成生物柴油的现状。简述了离子液体作为绿色溶剂的特性及对脂肪酶催化反应的影响,明确使用离子液体可提高酶的稳定性,维持酶的催化活性。综述了离子液体作为潜在的反应介质应用于脂肪酶催化高产生物柴油的前景。     

响应面法优化酶催化酯交换反应研究

为了利用植物油生产可再生的绿色能源——生物柴油,文章利用Novo435固定化脂肪酶,在无有机溶剂存在下催化菜籽油与甲醇酯交换合成生物柴油。利用响应面实验设计和分析方法对菜籽油的酯交换反应条件进行优化,得到了最佳工艺条件:醇油摩尔比1.5∶1,反应温度52℃,搅拌转速200 r/min,脂肪酶与油脂的质量比为10%,反应时间10 h,在此工艺条件下油脂的酯交换率达到48%(理论为50%)。理论甲醇量分3批加入,反应36 h后菜籽油的总酯交换率达到95%(理论酯交换率为100%)。每批试验后利用有机溶剂对脂肪酶进行清洗,然后继续反应,连续使用10个批次,油脂的酯交换率基本未变。     

固定化脂肪酶催化制备香叶树籽生物柴油研究

研究了Novozym 435和Lipozyme TLIM混合脂肪酶催化香叶树籽油制备生物柴油,2种酶按1:3质量比混合使用时,既可提高反应转化率,又可降低酶的使用成本.应用响应面优化法确定了固定化酶催化香叶树籽生物柴油的最优工艺参数,采用叔丁醇作为反应体系的溶剂,最优反应条件为反应温度38.5℃、甲醇与油摩尔比4:1、叔丁醇与油体积比1:1.5、酶用量为油质量的4%,此时反应转化率达90.09%.分析表明香叶树籽油的甘油三酯主要由短链脂肪酸甘油酯组成,生物柴油中原油的甘油三酯已完全转变成脂肪酸甲酯.     

新型反应介质中脂肪酶催化多种油脂制备生物柴油

用叔丁醇作为反应介质,利用固定化脂肪酶催化油脂原料甲醇醇解反应制备生物柴油,消除了甲醇和甘油对酶的负面影响,酶的使用寿命显著延长. 用菜籽油作原料,叔丁醇和油脂的体积比为1:1,甲醇与油脂的摩尔比为4:1,3%的Lipozyme TLIM和1%的Novozym 435结合使用,35℃下130 r/min反应12 h,生物柴油得率可达95%. 该工艺在200 kg/d的规模下制得的生物柴油产品完全满足美国和德国生物柴油标准,脂肪酶重复使用200批次,酶活性基本没有下降. 且在叔丁醇介质体系中大豆油、桐籽油、棉籽油、乌桕油、泔水油、地沟油和酸化油都能被有效转化成生物柴油且脂肪酶保持很好的稳定性.     

Immobilization of Pseudomonas cepacia lipase by sol-gel entrapment and its application in the hydrolysis of soybean oil

The immobilization of Lipase PS from Pseudomonas cepacia by entrapment within a chemically inert hydrophobic solgel support was studied. The gel-entrapped lipase was prepared by the hydrolysis of tetramethoxysilane (TMOS) with methyltrimethoxysilane (MTMS), isobutyltrimethoxysilane (iso-BTMS), and n-butyltrimethoxysilane. The immobilized lipase was subsequently used in the hydrolysis of soybean oil to determine its activity, recyclability, and thermostability. The biocatalyst so prepared was equal to or better than the free enzyme in its hydrolytic activity. The catalytic activity of the entrapped lipase strongly depended on the type of precursor that was used in its preparation. The lipase entrapped within TMOS/iso-BTMS showed the highest activity. The catalytic activity of the immobilized lipase was more pronounced during the earlier stages of the reaction. Thermostability of the lipase was significantly improved in the immobilized form. The immobilized lipase was stable up to 70°C, whereas for the free enzyme, moderate to severe loss of activity was observed beyond 40°C. The immobilized lipase was consistently more active and stable than the free enzyme. The immobilized lipase also proved to be very stable, as it retained more than 95% of its initial activity after twelve 1-h reactions.     

Investigation of synthetic lipase and its use in transesterification reactions

A novel synthetic polymer selective for p-nitrophenylpalmitate was synthesized by molecular imprinting technique. We have combined the principle of molecular imprinting with the ability of histidine, glutamic acid and serine to form a catalytic cavity that can promote the catalytic degradation of p-nitrophenyl palmitate.For the creation of such catalytic sites we first synthesized appropriate monomers and used p-nitrophenyl palmitate as a template to synthesize the imprinted polymers and the binding characteristics of the polymers were evaluated. The optimum pH was determined by evaluating different pH values and the hydrolytic activity of synthetic lipase was evaluated in the framework of Micheaelis–Menten kinetics. In addition, the values of maximal rate: Vm (0.68 mM/min) and Michaelis–Menten constant, Km (1.4 × 10^?2 mM) were obtained from Lineweaver–Burk plots for the imprinted polymeric catalyst.     

凹凸棒石粘土的改性及其在天然橡胶中的应用

采用异丙醇溶解的钛酸酯偶联剂NDZ-311对凹凸棒石粘土进行超声湿法表面改性。钛酸酯质量分数为4%时,改性效果最佳。改性后凹凸棒石粘土粉体的活化指数达最大值98%,吸油值由改性前的0.75mL/g下降到0.50mL/g,分散于50mL液体石蜡中形成的分散相在静置3h后其体积依然保持在48mL以上,稳定性较好。将改性过的凹凸棒石粘土应用到天然橡胶中,其ts1、t90均延长,拉伸强度、拉断伸长率、屈挠性均提高,但是胶料的撕裂强度和耐磨性能有所下降。     

Immobilization of lipase on chemically modified bimodal ceramic foams for olive oil hydrolysis

The work reported in this paper is aimed at exploring the feasibility of immobilizing alkali lipase from Penicillium expansum on a bimodal ceramic foam, which has both macro- and micro-pore structures. After being chemically modified with a silane coupling agent, the ceramic foam was used as a support for lipase immobilization. To determine the preferable immobilization conditions, the effects of the amount of enzyme for loading, immobilization time, temperature, and pH on enzyme activity were investigated. The results showed that the chemically modified ceramic foam has a high loading capacity and a strong binding ability for the lipase. Thanks to the low internal mass transfer resistance, the ceramic foam has greatly enhanced the rate of immobilization. As a comparison, the immobilized-lipase activity was much higher than that on many frequently used porous materials like diatomite, alumina and activated carbon.     

Calcium oxide as a solid base catalyst for transesterification of soybean oil and its application to biodiesel production

In order to study solid base catalyst for biodiesel production with environmental benignity, transesterification of edible soybean oil with refluxing methanol was carried out in the presence of calcium oxide (CaO), -hydroxide (Ca(OH)₂), or -carbonate (CaCO₃). At 1 h of reaction time, yield of FAME was 93% for CaO, 12% for Ca(OH)₂, and 0% for CaCO₃. Under the same reacting condition, sodium hydroxide with the homogeneous catalysis brought about the complete conversion into FAME. Also, CaO was used for the further tests transesterifying waste cooking oil (WCO) with acid value of 5.1 mg-KOH/g. The yield of FAME was above 99% at 2 h of reaction time, but a portion of catalyst changed into calcium soap by reacting with free fatty acids included in WCO at initial stage of the transesterification. Owing to the neutralizing reaction of the catalyst, concentration of calcium in FAME increased from 187 ppm to 3065 ppm. By processing WCO at reflux of methanol in the presence of cation-exchange resin, only the free fatty acids could be converted into FAME. The transesterification of the processed WCO with acid value of 0.3 mg-KOH/g resulted in the production of FAME including calcium of 565 ppm.     

Immobilization of <Emphasis Type="Italic">Candida rugosa</Emphasis> lipase by sol-gel entrapment and its application in the hydrolysis of soybean oil

Immobilization of lipase AY from Candida rugosa by entrapment within a chemically inert hydrophobic sol-gel support was studied. The gel-entrapped lipase was prepared by polycondensation of hydrolyzed tetramethoxysilane and isobutyltrimethoxysilane. Certain modifications were incorporated into the conventional immobilization procedure, including the use of glucose as additive and the application of vacuum during the drying and aging stages. The activity and thermostability of immobilized enzyme were subsequently determined in hydrolyzing soybean oil. Hydrolysis results showed more than 95 mol% of the theoretical yield for the formation of FF after 1 h of reaction at 40°C. The level of FFA was 3.3 times greater than that seen when an immobilized enzyme was prepared by the conventional sol-gel process. The immobilized enzyme retained most of its hydrolytic activity compared to the free enzyme and kept more than 95% activity after 120 h of incubation at 40°C, whereas the free enzyme lost 67% of its activity after 24 h of incubation and almost all of its activity after 96 h of incubation at 40°C. The immobilized enzyme also proved to be very stable, as it retained more than 90% of the initial activity after 16 one-hour reactions. Surface characterization studies suggested that the enzyme-containing sol-gel particles have amorphous morphology and are void of micro/meso pores.     

纳米管固定化生物分子及其应用

综述了纳米管固定化生物分子的几种主要方法,如交联法、吸附法、包埋法等,并简要地介绍了纳米管固定化生物分子在生物传感、生物催化和生物分离等领域的应用。