Sulfate radical-based advanced oxidation processes (SR-AOPs) show a good prospect for effective elimination of organic contaminants in water due to the powerful oxidation capability and good adaptability of sulfate radical (SO4•-). However, great concerns have been raised on occurrence of the carcinogenic byproduct bromate (BrO3-) in SR-AOPs. The present article aims to provide a critical review on BrO3- formation during bromine (Br)-containing water oxidation by various SR-AOPs. Potential reaction mechanisms are elaborated, mainly involving the sequential oxidation of bromide (Br-) by SO4•- to Br-containing radicals (e.g., bromine atom (Br•)) and then to hypobromous acid/hypobromite (HOBr/OBr-), which acts as the requisite intermediate for BrO3- formation. Some key influencing factors on BrO3- formation are discussed. Particularly, dissolved organic matter (DOM) as a component ubiquitously present in aquatic environments shows a significant suppression effect on BrO3- formation, primarily attributed to the reduction of Br• by DOM to Br-. The reaction of Br• with DOM can hardly produce organic brominated byproducts, while their formation is mainly due to the bromination of HOBr/OBr- generated through nonradical pathways such as the direct reaction of Br- with oxidants (e.g., peroxymonosulfate (PMS)) or other reactive species derived from catalytic activators (e.g., Co(III) in the Co(II)/PMS process). The debromination of brominated pollutants during their oxidation by SO4•- results in the release of Br-, which, however, is not further transformed to BrO3- until coexisting organic matters are mineralized nearly completely. Furthermore, possible strategies for control of BrO3- formation in SR-AOPs as well as the future research needs are proposed.

中文翻译：

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硫酸根自由基氧化工艺中溴酸盐的形成和控制，该工艺用于处理含溴化物的水：一项重要的综述。

基于硫酸根的高级氧化工艺（SR-AOP）由于具有强大的氧化能力和良好的硫酸根（SO4•-）适应性，因此有望有效消除水中的有机污染物。但是，人们对在SR-AOP中产生致癌副产物溴酸盐（BrO3-）引起了极大的关注。本文旨在就各种SR-AOP在含溴（Br）的水氧化过程中对BrO3-的形成提供重要的综述。阐述了潜在的反应机理，主要涉及通过SO4•-将溴化物（Br-）依次氧化为含溴的自由基（例如溴原子（Br•）），然后再氧化为次溴酸/次溴酸盐（HOBr / OBr-），它是形成BrO3-的必要中间体。讨论了影响BrO3-形成的一些关键因素。尤其，在水生环境中普遍存在的溶解有机物（DOM）表现出对BrO3-形成的显着抑制作用，这主要归因于DOM将Br•还原为Br-。Br•与DOM的反应几乎不会产生有机溴化副产物，而它们的形成主要是由于通过非自由基途径（例如Br-与氧化剂（例如过一硫酸氢盐（PMS））的直接反应）生成的HOBr / OBr-的溴化。或其他源自催化活化剂的反应性物种（例如，Co（II）/ PMS工艺中的Co（III））。溴污染物在被SO4•-氧化过程中脱溴会导致Br-的释放，但是直到并存的有机物几乎被完全矿化之前，Br-不会进一步转化为BrO3-。此外，