生質柴油之植物油脂萃取法比較

Abstract

菜籽油為高潛力的生質柴油原料，本研究旨在探討使用正己烷、乙醇與水作為萃取溶劑，進行不同菜籽油萃取方法的效率分析與可行性評估。本研究建立多級逆向萃取的數學模式並以兩種溶劑與固體比（E/R=4，8）實驗驗證其正確性，結果顯示E/R=4效果較佳，萃取收率達90%且萃取液濃度可達8∼9%（w/w）；本研究另以數學模式模擬不同級數與E/R比下，乙醇逆向萃取菜籽油，其結果顯示E/R=20的九級逆向萃取，萃取液濃度為1.5∼1.6%（w/w），萃取收率可達87%，然而萃取液濃度過低成為以乙醇同時萃取與交酯反應系統最大的阻礙。酵素輔助水萃取（AEOE）的試驗，果膠分解酶(Pectinase)水解油菜籽與黃豆萃取收率分別為69%和65%；蛋白質分解酶(Proteinase)水解油菜籽與黃豆萃取收率分別為58%和70%。酵素輔助水萃取雖可減少能源的消耗，但是萃取收率低與油水分離困難使其成效不及有機溶劑萃取。

Rapeseed oil is one the major feed stocks for biodiesel with great potential. The feasibility and efficiency of various rapeseed oil extraction systems with hexane, ethanol and water as solvents were studied and compared. Mathematical model of multi-stage counter-current-flow extraction was build and verified in this research. Six-stage counter-current-flow extraction experiments were carried with two different solvent to raffinate ratio (E/R) i.e. E/R=4, 8. A better result was found with E/R=4, that gave 90% in oil recovery and 8~9% (w/w) oil concentration in extract. Counter-current-flow ethanol-rapeseed oil extraction with varies stages and E/R ratios were simulated. A nine-stage extraction with E/R=20 shown that the oil concentration in ethanol was 1.5~1.6% (w/w) and oil recovery was 87%. Although extraction-transesterification might be considered for the ethanol - rapeseed oil system, but the oil concentration in extract might obstruct the idea to be practical. In respect of Aqueous Enzymatic Oil Extraction (AEOE), pectinase and proteinase were used for rapeseed and soybean oil extraction. Oil recovery was 69% and 65% respectively as pectinase was used. Oil recovery was 58% and 70% respectively as proteinase was used. AEOE might be a process with less energy consumed, but inefficient in extraction yields and oil recovery from solution would be the main difficulty to be overcome.