title: Degradation pathway and kinetics of 1-alkyl-3-methylimidazolium bromides oxidation in an ultrasonic nanoscale zero-valent iron/hydrogen peroxide system.
abstract: Fenton and Fenton-like oxidation has been already demonstrated to be efficient for the degradation of imidazolium ionic liquids (ILs), but little is known for their degradation pathway and kinetics in such systems. In this work, degradation pathway and kinetics of 1-alkyl-3-methylimidazolium bromides ([Cnmim]Br, n=2, 4, 6, 8, and 10) were investigated in an ultrasound nanoscale zero-valent iron/hydrogen peroxide (US-nZVI/H2O2) system. For this purpose, 1-butyl-3-methylimidazolium bromide ([C4mim]Br) was used as a representative ionic liquid to optimize pH value, nZVI dose, and H2O2 concentration for the degradation reaction. Then, the degradation kinetics of [Cnmim]Br was investigated under optimal conditions, and their degradation intermediates were monitored by gas chromatography-mass spectrometry (GC-MS). It was shown that the degradation of [Cnmim]Br in such a heterogeneous Fenton-like system could be described by a second order kinetic model, and a number of intermediate products were detected. Based on these intermediate products, detailed pathways were proposed for the degradation of [Cnmim]Br in the ultrasound-assisted nZVI/H2O2 system. These findings may be useful for the better understanding of degradation mechanism of the imidazolium ILs in aqueous solutions.
authors.affiliation: Faculty of Forensic Medicine, Henan University of Science and Technology, Luoyang, Henan 471003, PR China.
authors.forename: Haimei
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Faculty of Forensic Medicine, Henan University of Science and Technology, Luoyang, Henan 471003, PR China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Faculty of Forensic Medicine, Henan University of Science and Technology, Luoyang, Henan 471003, PR China.
authors.forename: Ping
authors.initials: P
authors.lastname: Lv
authors.affiliation: School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang, Henan 453007, PR China. Electronic address: jwang@henannu.edu.cn.
authors.forename: Jianji
authors.initials: J
authors.lastname: Wang
authors.affiliation: Faculty of Forensic Medicine, Henan University of Science and Technology, Luoyang, Henan 471003, PR China.
authors.forename: Pu
authors.initials: P
authors.lastname: Li
mesh_terms: D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D010100:Oxygen / Q000737:chemistry; D010316:Particle Size; D011208:Powders; D014465:Ultrasonics; D062065:Wastewater; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification
chemical_list: D006861:Hydrogen Peroxide; D007093:Imidazoles; D052578:Ionic Liquids; D010100:Oxygen; D011208:Powders; D062065:Wastewater; D014874:Water Pollutants, Chemical; C502841:1-butyl-3-methylimidazolium chloride
keywords: Degradation pathway; Hydrogen peroxide; Ionic liquid; Nanoscale zero-valent iron; Ultrasound