title: Identification of degradation products of ionic liquids in an ultrasound assisted zero-valent iron activated carbon micro-electrolysis system and their degradation mechanism.
abstract: Ionic liquids (ILs) have potential applications in many areas of chemical industry because of their unique properties. However, it has been shown that the ILs commonly used to date are toxic and not biodegradable in nature, thus development of efficient chemical methods for the degradation of ILs is imperative. In this work, degradation of imidazolium, piperidinium, pyrrolidinium and morpholinium based ILs in an ultrasound and zero-valent iron activated carbon (ZVI/AC) micro-electrolysis system was investigated, and some intermediates generated during the degradation were identified. It was found that more than 90% of 1-alkyl-3-methylimidazolium bromide ([Cnmim]Br, n = 2, 4, 6, 8, 10) could be degraded within 110 min, and three intermediates 1-alkyl-3-methyl-2,4,5-trioxoimidazolidine, 1-alkyl-3-methylurea and N-alkylformamide were detected. On the other hand, 1-butyl-1-methylpiperidinium bromide ([C4mpip]Br), 1-butyl-1-methylpyrrolidinium bromide ([C4mpyr]Br) and N-butyl-N-methylmorpholinium bromide ([C4mmor]Br) were also effectively degraded through the sequential oxidization into hydroxyl, carbonyl and carboxyl groups in different positions of the butyl side chain, and then the N-butyl side chain was broken to form the final products of N-methylpiperidinium, N-methylpyrrolidinium and N-methylmorpholinium, respectively. Based on these intermediate products, degradation pathways of these ILs were suggested. These findings may provide fundamental information on the assessment of the factors related to the environmental fate and environmental behavior of these commonly used ILs.
authors.affiliation: College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, PR China.
authors.forename: Haimei
authors.initials: H
authors.lastname: Zhou
authors.forename: Ping
authors.initials: P
authors.lastname: Lv
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Shen
authors.forename: Jianji
authors.initials: J
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Fan
mesh_terms: D002606:Charcoal; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004572:Electrolysis / Q000379:methods*; D004785:Environmental Pollutants / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D007093:Imidazoles / Q000737:chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D007501:Iron; D009025:Morpholines / Q000737:chemistry; D010880:Piperidines / Q000737:chemistry; D011759:Pyrrolidines / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D004785:Environmental Pollutants; D007093:Imidazoles; D052578:Ionic Liquids; D009025:Morpholines; D010880:Piperidines; D011759:Pyrrolidines; D002606:Charcoal; D007501:Iron