热活化过硫酸钠降解水体中咪唑氯盐类离子液体

Degradation of Imidazolium Chloride Ionic Liquids in Water by Thermally Activated Sodium Persulfate

离子液体(ionic liquids,ILs)具有较高的化学稳定性和抗生物降解性,尤其是广泛使用的咪唑基离子液体,由于其存在潜在的生态毒性和环境风险,所以高效去除水体环境中的离子液体迫在眉睫。本实验采用热活化过硫酸钠高级氧化技术降解水体中的1–乙基–3–甲基咪唑氯盐(EMICl),考察不同反应体系、反应温度、氧化剂投加量、初始pH和共存无机阴离子对离子液体降解效果的影响。结果表明,与单独加热和单独过硫酸钠氧化相比,热活化过硫酸钠能有效降解EMICl。在反应温度为60℃、过硫酸钠投加量为1 mmol/L、初始pH为7.0时,2 h内EMICl(10 mg/L)的去除率高达96.55%。此外,EMICl的降解符合准一级反应动力学,EMICl氧化时的活化能为94.45 kJ/mol。硫酸根自由基(SO_(4)^(·−))和羟自由基(·OH)是降解EMICl的主要活性物质。密度泛函理论(density functional theory,DFT)计算结果表明,EMICl首先被攻击的主要位点是咪唑环上的C原子,其次是烷基侧链。

Ionic liquids(ILs)have high chemical stability and resistance to biodegradation,especially the widely used imidazolium-based ILs,and their efficient removal from the water environment is imminent due to their potential ecotoxicity and environmental risks.In this experiment,1-ethyl-3-methylimidazolium chloride(EMICl)in water was degraded by thermally activated sodium persulfate advanced oxidation processes,and the effects of different reaction systems,reaction temperature,oxidant dosage,initial pH and coexisting inorganic anions on the degradation effect of ILs were investigated.The results showed that thermally activated sodium persulfate could effectively degrade ionic liquids compared to thermal alone and sodium persulfate alone.The removal rate of EMICl(10 mg/L)was up to 96.55%in 2 h when the reaction temperature was 60℃,the sodium persulfate dosage was 1 mmol/L,and the initial pH was 7.0.Moreover,the degradation of EMICl was followed the pseudo-first-order reaction kinetics,with an activation energy of 94.45kJ/mol for the EMICl oxidation.SO_(4)^(·−)and·OH were the main active species for the degradation of EMICl.Density functional theory(DFT)calculations indicated that the first major site attacked by EMICl were the C atoms on imidazolium ring,followed by the alkyl side chain.