固定脂肪酶於幾丁聚醣／氧化石墨烯複合膜以製備滲透蒸發型酵素膜反應器

Enhanced transesterification by immobilized lipase on chitosan／graphene oxide composite membrane bioreactor through pervaporation

張文銓(Wen-Chuan Chang)

指導教授 ： 周崇榮

中原大學/工學院/化學工程研究所/碩士(2017年)

https://doi.org/10.6840/cycu201700706

摘要

在這注重環保、講究節能省碳的綠色工業時代，酵素工程為近年來著重推廣的綠色技術，而生質柴油更是人類發展多年的燃料能源替代品，因此本研究將兩者結合，運用對環境友善的方式生產對地球無負擔的生質柴油，將脂肪酶的催化特性應用於酯類的水解及轉酯化反應中，本研究重點領域為運用膜反應器將酵素固定化與薄膜技術結合，並接連滲透蒸發達到催化與分離並行的效果，再利用此特性有效合成出生質柴油(FAME)。
本實驗將具有優良生物相容性的幾丁聚醣與表面富含氧化官能基且機械強度甚佳的氧化石墨烯混合製成複合膜，再將皺褶假絲酵母脂肪酶固定化於其表面，探討長時間水解反應下最佳的混合比例及溫度條件，並利用此條件和酵素膜反應器催化三酸甘油酯的水解反應及轉酯化反應進而合成出生質柴油，並透過滲透蒸發達到提升轉酯率的效果，再藉由氣相層析儀檢測分析。
結果顯示脂肪酶固定化於CS/GO1:0.25複合膜在45℃擁有高達96.8%的水解轉化率，高於幾丁聚醣複合膜及表面產生插層的CS/GO1:0.5複合膜，並將此條件應用於三酸甘油酯轉酯化成生質柴油的反應中，結果不但成功轉酯化，而且反應器結合打氣機或滲透蒸發程序還可將轉酯率提升至91.3%及92.1%，也證明此酵素膜反應器之優點與完整系統之應用，期望未來再做改良調整並應用於更多特用化學品之合成反應。

關鍵字

脂肪酶 ； 固定化 ； 轉酯化 ； 膜反應器 ； 滲透蒸發

並列摘要

Recently, environmental protection, energy efficiency and carbon reduction are increasingly important in chemical engineering field. Enzyme technology is considered as a viable option in green energy production, including alternative fuel such as biodiesel. The primary principle of biodiesel synthesis is the subsequent hydrolysis and transesterification of vegetable oil by lipase enzyme catalysts. Moreover, combination of membrane fabrication technology, and immobilization enzyme techniques would increase the overall reaction efficiency and cost through better enzyme stability and surface reaction kinetics.
In this work, chitosan, and graphene oxide were mixed in proper ratio and casted onto pervaporative polysulfone membrane for immobilization of Candida rugosa lipase for hydrolysis reaction and transesterification of soybean oil. A membrane bioreactor was set up and connected with real time UV-VIS spectroscopy to interrogate the kinetic effects of different CS/GO ratio in composite membranes and optimal temperature. Subsequently, the membrane reactor was challenged with two phase (oil-water-methanol) transesterification reaction for fatty acid methyl ester (FAME) production. The integrity and surface phenotype was observed with scanning electronic microscope (SEM). The results suggested that the graphene oxide doping may affect the affinity of oil toward the composite membrane surface.
Results suggested that the lipase immobilized on CS/GO1:0.25 composite membrane in 45℃ exhibited the optimal 96.8% hydrolysis ratio of para-nitrophenyl palmitate (pNPP) among all operational parameters. Next, the transesterification capability of this enzymatic complexed membrane was compared through three different operational modes, including atmospheric vaporization, convective vaporization and pervaporation. The results showed that the convective vaporization and pervaporation modes can improve transesterification ratio to 91.3% and 92.1%, respectively. As result, the reactor design based on chitosan-graphene composite membrane could increase the enzyme stability and kinetics performance of the immobilized lipase, and could be applied to fine chemical production in the future.

並列關鍵字

lipase ； immobilized ； transesterification ； membrane reactor ； pervaporation

參考文獻

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