Sección de Ingeniería Química, Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049, Madrid, Spain.
Environ Sci Pollut Res Int. 2018 Dec;25(35):34930-34937. doi: 10.1007/s11356-017-0867-4. Epub 2018 Jan 9.
The oxidation of imidazolium (1-hexyl-3-methylimidazolium chloride, HmimCl) and pyridinium (1-butyl-4-methylpyridinium chloride, BmpyrCl) ionic liquids (ILs) by Fenton's reagent has been studied. Complete conversion was achieved for both ILs using the stoichiometric HO dose at 70 °C, reaching final TOC conversion values around 45 and 55% for HmimCl and BmpyrCl, respectively. The decrease in hydrogen peroxide dose to substoichiometric concentrations (20-80% stoichiometric dose) caused a decrease in TOC conversion and COD removal and the appearance of hydroxylated oxidation by-products. Working at these substoichiometric HO doses allowed the depiction of a possible degradation pathway for the oxidation of both imidazolium and pyridinium ILs. The first step of the oxidation process consisted in the hydroxylation of the ionic liquid by the attack of the ·OH radicals, followed by the ring-opening and the formation of short-chain organic acids, which could be partially oxidized up to CO and HO. At HO doses near stoichiometric values (80%), the resulting effluents showed non-ecotoxic behaviour and more biodegradable character (BOD/COD ratio around 0.38 and 0.58 for HmimCl and BmpyrCl, respectively) due to the formation of short-chain organic acids. Graphical abstract ᅟ.
用过氧化氢/亚铁离子试剂氧化离子液体 1-己基-3-甲基咪唑氯（HmimCl）和 1-丁基-4-甲基吡啶氯（BmpyrCl）的反应已经被研究过了。在 70°C 时，使用化学计量的 HO 剂量，可以完全转化这两种 IL，对于 HmimCl 和 BmpyrCl，最终 TOC 转化率分别约为 45%和 55%。将过氧化氢剂量降低至亚化学计量浓度（20%-80%化学计量剂量）会导致 TOC 转化率和 COD 去除率降低，并出现羟化氧化副产物。在这些亚化学计量的 HO 剂量下，可以描绘出氧化咪唑鎓和吡啶鎓 IL 的可能降解途径。氧化过程的第一步是由·OH 自由基攻击离子液体的羟化，然后是开环和短链有机酸的形成，这些有机酸可以部分氧化至 CO 和 HO。在接近化学计量值（80%）的 HO 剂量下，由于短链有机酸的形成，所得流出物表现出非生态毒性行为和更高的可生物降解性（对于 HmimCl 和 BmpyrCl，BOD/COD 比分别约为 0.38 和 0.58）。
