Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999066, China; Advanced Interdisciplinary Institute of Environment and Ecology, Beijing Normal University at Zhu Hai, Zhu Hai, Hong Kong 519087, China.
Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999066, China.
Water Res. 2022 Aug 15;222:118886. doi: 10.1016/j.watres.2022.118886. Epub 2022 Jul 21.
Chlorine dioxide (ClO) is used as an oxidant or disinfectant in (waste)water treatment, whereas sulfite is a prevalent reducing agent to quench the excess ClO. This study demonstrated that seven micropollutants with structural diversity could be rapidly degraded in the reaction between ClO and sulfite under environmentally relevant conditions in synthetic and real drinking water. For example, carbamazepine, which is recalcitrant to standalone ClO or sulfite, was degraded by 55%-80% in 10 s in the ClO/sulfite process at 30-µM ClO and 30-µM sulfite concentrations within a pH range of 6.0-11.0. Results from experiments and a kinetic model supported that chlorine monoxide (ClO) and sulfate radicals (SO) were generated in the ClO/sulfite process, while hydroxyl radical generation was insignificant. Apart from radicals, dichlorine trioxide (ClO) was generated and largely contributed to micropollutant degradation, supported by experimental results using stopped-flow spectrometry and quantum chemical calculations. The impacts of pH, sulfite dosage, and water matrix components (chloride, bicarbonate, and natural organic matter) on micropollutant abatement in the ClO/sulfite process were evaluated and discussed. When treating the real potable water, the concentrations of organic (five regulated disinfection byproducts) and inorganic byproducts (chlorite and chlorate) formed in the ClO/sulfite process were all below the drinking water standards. This study disclosed fundamental knowledge advancements relevant to the reaction mechanisms between ClO and sulfite, and highlighed a novel process to abate micropollutants in water and wastewater.
二氧化氯（ClO）在（废水）水处理中用作氧化剂或消毒剂，而亚硫酸盐是一种常见的还原剂，用于消耗过量的 ClO。本研究表明，在合成和实际饮用水中环境相关条件下，ClO 和亚硫酸盐之间的反应可以快速降解具有结构多样性的七种微量污染物。例如，在 30-µM ClO 和 30-µM 亚硫酸盐浓度范围内，pH 值为 6.0-11.0 时，卡马西平（一种对单独的 ClO 或亚硫酸盐具有抗降解性的物质）在 10 秒内可被 ClO/亚硫酸盐工艺降解 55%-80%。实验和动力学模型的结果表明，ClO/亚硫酸盐工艺中生成了一氯化氧（ClO）和硫酸根自由基（SO），而羟基自由基的生成可以忽略不计。除自由基外，二氯三氧化物（ClO）也被生成，并在实验结果中得到支持，使用停流光谱法和量子化学计算表明，ClO 对微量污染物的降解起主要作用。实验还评估和讨论了 pH 值、亚硫酸盐用量以及水基质成分（氯离子、碳酸氢根和天然有机物）对 ClO/亚硫酸盐工艺中微量污染物去除的影响。当处理实际饮用水时，ClO/亚硫酸盐工艺中形成的有机（五种受管制的消毒副产物）和无机副产物（亚氯酸盐和氯酸盐）的浓度均低于饮用水标准。本研究揭示了有关 ClO 和亚硫酸盐反应机制的基本知识进展，并强调了一种新的工艺，可以去除水中和废水中的微量污染物。
