Zhou Haimei, Lv Ping, Qi Hang, Ma Jinqi, Wang Jianji
a Faculty of Forensic Medicine, Henan University of Science and Technology , Luoyang , Henan , People's Republic of China.
b School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University , Xinxiang , Henan , People's Republic of China.
Environ Technol. 2019 Aug;40(19):2504-2512. doi: 10.1080/09593330.2018.1444101. Epub 2018 Mar 2.
Numerous applications of ionic liquids (ILs) are often accompanied by the generation of aqueous wastes. Due to the high toxicity and poor biodegradability of ILs, effective chemical treatment is of great importance for their removal from aqueous solution. In this work, an ultrasound-assisted zero-valent iron/activated carbon (US-ZVI/AC) micro-electrolysis technique was used to degrade residual functionalized ILs, 1-butyl-3-methyl benzimidazolium bromide ([BMBIM]Br) and 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) in aqueous solution, and the degradation degree, degradation kinetics and possible degradation pathways were investigated. It was shown that the degradation of these functionalized ILs was highly efficient in the US-ZVI/AC system, and the degradation degree was as high as 96.1% and 92.9% in 110 min for [BMBIM]Br and [AMIM]Cl, respectively. The degradation of [BMBIM]Br could be described by the second-order kinetics model, and [BMBIM] was decomposed in two ways: (i) sequential cleavage of N-alkyl side chain of the cation produced three intermediates; (ii) the 2-positioned H atoms of the benzimidazolium ring were first oxidized, and then the imidazolium ring was opened. The degradation of [AMIM]Cl followed the first-order kinetics rule, and the 2,4,5-positioned H atoms of the imidazolium ring were oxidized to induce ring opening. In addition, the removal of total organic carbon was found to be >87%, which indicates that most of the ILs was mineralized in the degradation process. These results suggest that ultrasound-assisted ZVI/AC micro-electrolysis is highly effective for the removal of residual functionalized ILs from aqueous environment.
离子液体（ILs）的众多应用常常伴随着含水性废物的产生。由于离子液体具有高毒性和低生物降解性，有效的化学处理对于从水溶液中去除它们至关重要。在本研究中，采用超声辅助零价铁/活性炭（US-ZVI/AC）微电解技术降解水溶液中残留的功能化离子液体1-丁基-3-甲基苯并咪唑溴盐（[BMBIM]Br）和1-烯丙基-3-甲基咪唑氯盐（[AMIM]Cl），并研究了其降解程度、降解动力学及可能的降解途径。结果表明，在US-ZVI/AC体系中，这些功能化离子液体的降解效率很高，对于[BMBIM]Br和[AMIM]Cl，在110分钟内降解程度分别高达96.1%和92.9%。[BMBIM]Br的降解可用二级动力学模型描述，[BMBIM]通过两种方式分解：（i）阳离子的N-烷基侧链依次断裂产生三种中间体；（ii）苯并咪唑环2位的H原子先被氧化，然后咪唑环开环。[AMIM]Cl的降解遵循一级动力学规律，咪唑环2、4、5位的H原子被氧化导致开环。此外，发现总有机碳的去除率>87%，这表明在降解过程中大部分离子液体被矿化。这些结果表明，超声辅助ZVI/AC微电解对于从水环境中去除残留的功能化离子液体非常有效。
