Removal of imidazolium- and pyridinium-based ionic liquids by Fenton oxidation
Removal of imidazolium- and pyridinium-based ionic liquids by Fenton oxidation
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DOI：
10.1007/s11356-017-0867-4
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发表时间：
2018-12-01
影响因子：
5.8
通讯作者：
Mohedano, Angel F.
中科院分区：
文献类型：
--
作者：
Gomez-Herrero, Esther;Tobajas, Montserrat;Mohedano, Angel F.
研究了芬顿试剂对咪唑（1-己基-3-甲基咪唑氯化物，HmimCl）和吡啶（1-丁基-4-甲基吡啶氯化物，BmpyrCl）离子液体的氧化性能.使用化学计量的H2 O2剂量在70 ℃下实现了两种IL的完全转化，对于HmimCl和BmpyrCl分别达到约45%和55%的最终TOC转化率值。过氧化氢剂量降低至亚化学计量浓度（20-80%化学计量剂量）导致TOC转化率和COD去除率降低以及羟基化氧化副产物的出现。在这些亚化学计量H2 O2剂量下工作允许描绘咪唑鎓和吡啶鎓离子液体氧化的可能降解途径。氧化过程的第一步是通过中心点OH自由基的攻击使离子液体羟基化，然后开环并形成短链有机酸，其可以部分氧化为CO2和H2O。在H2 O2剂量接近化学计量值（80%），所产生的废水显示出非生态毒性行为和更生物降解的字符（BOD 5/COD比约0.38和0.58的HmimCl和BmpyrCl，分别），由于形成短链有机酸。
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 H2O2 dose at 70 degrees 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 H2O2 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 center dot OH radicals, followed by the ring-opening and the formation of short-chain organic acids, which could be partially oxidized up to CO2 and H2O. At H2O2 doses near stoichiometric values (80%), the resulting effluents showed non-ecotoxic behaviour and more biodegradable character (BOD5/COD ratio around 0.38 and 0.58 for HmimCl and BmpyrCl, respectively) due to the formation of short-chain organic acids.