State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Key Laboratory of Urban Water Supply, Water Saving and Water Environment Governance in the Yangtze River Delta of Ministry of Water Resources, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai,200092, China.
Water Res. 2024 Nov 1;265:122270. doi: 10.1016/j.watres.2024.122270. Epub 2024 Aug 15.
Peracetic acid (PAA) is an alternative disinfectant for saline wastewaters, and hypohalous acids are typically regarded as the reactive species for oxidation and disinfection. However, new results herein strongly suggest that reactive radicals instead of HOI primarily contributed to decontamination during PAA treatment of iodine-containing wastewater. The presence of I could greatly accelerate the micropollutants (e.g., sulfamethoxazole (SMX)) transformation by PAA. Chemical probes experiments and electron paramagnetic resonance analysis demonstrate acetylperoxyl radical rather than reactive iodine species primarily responsible for SMX degradation. The kinetic model was developed to further distinguish and quantify the contribution of radicals and iodine species, as well as to elucidate the transformation pathways of iodine species. Density functional theory calculations indicated that the nucleophilic attack of I on the peroxide bond of PAA could form unstable O-I bond, with the transition state energy barrier for radical generation lower than that for HOI formation. The transformation of iodine species was regulated by acetylperoxyl radical to generate nontoxic IO, greatly alleviating the iodinated DBPs formation in saline wastewaters. This work provides mechanistic insights in radical-regulated iodine species transformation during PAA oxidation, paving the way for the development of viable and eco-friendly technology for iodide containing water treatment.
过氧乙酸（PAA）是盐水废水的替代消毒剂，次卤酸通常被认为是氧化和消毒的反应性物质。然而，本文中的新结果强烈表明，在 PAA 处理含碘废水的过程中，反应性自由基而不是 HOI 主要有助于去污。I 的存在可以大大加速微污染物（例如磺胺甲恶唑（SMX））通过 PAA 的转化。化学探针实验和电子顺磁共振分析表明，乙酰过氧自由基而不是反应性碘物种主要负责 SMX 的降解。建立了动力学模型以进一步区分和量化自由基和碘物种的贡献，并阐明碘物种的转化途径。密度泛函理论计算表明，I 对 PAA 过氧键的亲核攻击可以形成不稳定的 O-I 键，自由基生成的过渡态能垒低于 HOI 形成的过渡态能垒。碘物种的转化受乙酰过氧自由基的调节，生成无毒的 IO，从而大大减轻了含盐水废水中碘代 DBPs 的形成。这项工作为 PAA 氧化过程中自由基调控的碘物种转化提供了机理见解，为开发可行和环保的含碘水处理技术铺平了道路。
