离子液体降解性的研究进展

离子液体作为绿色溶剂,在电化学、有机化学、生物化学等领域获得了广泛重视,但目前研究主要集中于离子液体的合成和应用,而与环保问题直接相关的降解性方面的研究不足,实现离子液体的降解是离子液体大规模使用之前必须要解决的问题。本文综述了离子液体的降解方法:化学降解法和生物降解法。化学降解法主要通过UV/H₂O₂体系、Fe(Ⅲ)/H₂O₂体系、电解体系实现对离子液体的降解;生物降解法则通过引入可以提供酶解位点的基团,或者单加氧酶将离子液体阳离子烷基侧链甲基末端氧化为羟基、醛基,形成羧基,再进行β-氧化过程。提出了针对化学降解法和生物降解法机理的不同,需要对离子液体的化学结构进行设计、适当控制烷基侧链的长度、引入易降解的功能基团等;同时筛选微生物,进而提高离子液体的降解效率。

Research progress in degradation of ionic liquids

As “green solvents”, ionic liquids have attracted much attention in the area of electrochemistry, organic chemistry and biochemistry. Recent studies focus on the synthesis and application of ionic liquids.However, the studies on degradation of ionic liquids which concerned with environment are not enough. The degradation of ionic liquids is required before the large-scale use of ionic liquids. In this study, chemical degradation method and biodegradation method are summarized. The chemical degradation is mainly achieved by UV/H₂O₂, Fe (Ⅲ)/H₂O₂ and electrolysis system. Biological degradation is achieved by introducing functional groups with enzymatic site, or using monooxygenase to oxidize the methyl terminal of alkyl side chain on the cation of ionic liquids into hydroxyl and aldehyde to form carboxylic groups, and then β-oxidation is proceed. Different chemical structures of ionic liquids is designed according to different mechanism between chemical and biological degradation, for example, changing the length of alkyl chain or introducing the functional groups that are easily degradable and selection of microorganism could improve efficiency of degradation of ionic liquids.