Abstract：
The practical application of Cu(II)-catalyzed Fenton-like reaction (Cu(II)/H2O2) exhibits a low efficiency in the degradation of refractory compounds of wastewater. The impact of chloride ions (Cl-) on Fenton-like reactions have been investigated, but the influence mechanism is still unclear. Herein, the presence of Cl- (5 mM) significantly accelerated the degradation of benzoic acid (BA) under neutral conditions. The degradation of BA follows pseudo-first-order kinetics, with a degradation rate 7.3 times higher than the Cu(II)/H2O2 system. Multiple evidences strongly demonstrated that this reaction enables the production of reactive chlorine species (RCS) rather than HO• and high-valent copper (Cu(III)). The kinetic model revealed that Cl- could shift reactive species from the key intermediate (Cu(III)-chloro complexes) to RCS. Dichlorine radicals (Cl2•-) was discovered to play a crucial role in BA degradation, which was largely overlooked in previous reports. Although the reaction rate of Cl2•- with BA (k = 2.0 × 106 M-1 s-1) is lower than that of other species, its concentration is 10 orders of magnitude higher than that of Cu(III) and HO•. Furthermore, the exceptional efficacy of the Cu(II)/H2O2 system in BA degradation was observed in saline aquatic environments. This work sheds light on the previously unrecognized role of the metal-chloro complexes in production the RCS and water purification.
摘要：
Cu（II）催化的类Fenton反应（Cu（II）/H2O2）的实际应用在降解废水的难降解化合物方面表现出低效率。已经研究了氯离子（Cl-）对类Fenton反应的影响，但其影响机制尚不清楚。在这里，Cl-（5mM）的存在显着加速了中性条件下苯甲酸（BA）的降解。BA的降解遵循伪一级动力学，其降解速率比Cu(II)/H2O2体系高7.3倍。大量证据有力地证明，该反应能够产生活性氯物质（RCS），而不是HO•和高价铜（Cu（III））。动力学模型表明，Cl-可以将反应性物质从关键中间体（Cu（III）-氯配合物）转移到RCS。发现二氯自由基(Cl2·-)在BA降解中起关键作用，这在以前的报告中被忽略了。尽管Cl2·-与BA的反应速率（k=2.0×106M-1s-1）低于其他物种，其浓度比Cu(III)和HO•高10个数量级。此外，在盐水环境中观察到Cu（II）/H2O2系统在BA降解中的特殊功效。这项工作揭示了金属-氯配合物在生产RCS和水净化中先前未被认识到的作用。
