Shanghai Key Laboratory of Urbanization and Ecological Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; College of Environmental Science and Engineering, Donghua University, Shanghai 201620, China; Institute of Eco-Chongming (IEC), Shanghai 200062, China.
College of Environmental Science and Engineering, Donghua University, Shanghai 201620, China.
Environ Int. 2019 Nov;132:105128. doi: 10.1016/j.envint.2019.105128. Epub 2019 Sep 1.
The roles of chloride in enhanced oxidative degradation of refractory organic pollutants are recently identified in the Cu(II)/HO/Cl system, but the identity of the reactive oxidants and potential conversion of inorganic chloride to organochlorine in such oxidizing environment remain obscure. Here we report that Cu(II)/HO/Cl system is a unique "halotolerant" Fenton-like process that works most efficiently in saline water among the five tested redox-active metals ions (i.e. Cr(VI), Ce(III), Co(II), Mn(II) and Cu(II)). The observed pseudo first-order rate constant for 2,4,6-trichlorophenol (TCP) degradation was linearly correlated with the elevated Cl content. The TCP degradation rate at [Cl] = 1000 mM by the Cu(II)/HO system was approximately 46-fold higher than that at [Cl] = 5 mM. The optimal mineralization rate of TCP and percentage of absorbable organic halogens (AOX) decrease were 31.6% and 63.8%, respectively, in the tested Cu(II)/HO/Cl system. However, the detection of fused chlorinated byproducts (i.e. chloro-anthracene-pentaol, dioxine, chlorinated dibenzofuran) reminds us of cautiousness in evaluating the applicability of Cu(II)-catalyzed Fenton-like reaction, particularly while it is to be applied to the treatment of wastewater contaminated with chlorophenols. Two independent models (i.e. "Cu(III) model" and "OH model") were developed to describe the kinetics of Cu(II)/HO/Cl system. The failure of "OH model" to rationalize the observed AOX decay has disproved the "OH model" through reductio ad absurdum. The ability of "Cu(III) model" to adequately explain the experimental data demonstrates that Cu(III)-chloro complexes, rather than OH, is the major product resulting from reactions between Cu(I)-chloro complexes and HO at neutral pH.
在 Cu(II)/HO/Cl 体系中，最近发现氯离子在增强难降解有机污染物的氧化降解中起作用，但在这种氧化环境中，反应性氧化剂的身份以及无机氯化物向有机氯化物的潜在转化仍然不清楚。在这里，我们报道 Cu(II)/HO/Cl 体系是一种独特的“耐盐”类芬顿反应，在五种测试的氧化还原活性金属离子（即 Cr(VI)、Ce(III)、Co(II)、Mn(II)和 Cu(II)）中，在盐水中的效率最高。观察到的 2,4,6-三氯苯酚 (TCP) 降解的表观一级反应速率常数与升高的 Cl 含量呈线性相关。在 Cu(II)/HO 体系中，[Cl]为 1000 mM 时的 TCP 降解速率约比[Cl]为 5 mM 时高 46 倍。在测试的 Cu(II)/HO/Cl 体系中，TCP 的最佳矿化率和可吸收有机卤化物（AOX）的百分比分别为 31.6%和 63.8%。然而，检测到的融合氯化副产物（即氯蒽五醇、二恶英、氯化二苯并呋喃）提醒我们在评估 Cu(II)催化类芬顿反应的适用性时要谨慎，特别是在将其应用于处理含氯酚的废水时。提出了两种独立的模型（即“Cu(III)模型”和“OH 模型”）来描述 Cu(II)/HO/Cl 体系的动力学。“OH 模型”无法合理推断出观察到的 AOX 衰减，这通过归谬法证明了“OH 模型”的失败。“Cu(III)模型”能够充分解释实验数据，表明 Cu(III)-氯络合物而不是 OH 是 Cu(I)-氯络合物与 HO 在中性 pH 下反应的主要产物。
