Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou 510006, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China.
Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou 510006, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China.
Water Res. 2022 Jun 1;216:118331. doi: 10.1016/j.watres.2022.118331. Epub 2022 Mar 22.
Recently, bisulfite-activated permanganate (MnO; Mn(VII)) process has attracted considerable attention as a novel class of advanced oxidation technology for destruction of organic contaminants in water. However, disputes over the underlying activation mechanism as well as reactive species generated in the Mn(VII)/bisulfite system remain for a long period due to the fairly complex chemistry involved in this system. This article aims to present a critical review on scientific development of the Mn(VII)/bisulfite system, with particular focus on the generation and contribution of various reactive intermediates. Both reactive manganese species (RMnS) (i.e., soluble Mn(III), Mn(V), and Mn(VI)) and radical species (primarily SO) are identified as the oxidizing components responsible for enhanced degradation of organic contaminants by the Mn(VII)/bisulfite system. Bisulfite plays a dual role of being an activating agent for reactive intermediates generation and acting as a complexing agent to stabilize RMnS. Solution chemistry (e.g., the [Mn(VII)]/[bisulfite] molar ratio, solution pH, the type of contaminants, ligands, and water matrix components) greatly impacts the generation and consumption of RMnS and radicals, thus influencing the degradation kinetics and pathways of organics. Particularly, dissolved oxygen (DO) is a vital factor for driving the oxidation of organics since the absence of DO can block the generation of SO and meantime causes the consumption of RMnS by excess SO as a strong reductant. Interestingly, ferrate (FeO, Fe(VI)) and hexavalent chromium (CrO/HCrO, Cr(VI)) that are high-valent metal oxyanions analogous to Mn(VII) can be activated by bisulfite via a similar pathway (i.e. both high-valent metal-oxo intermediates and reactive radicals are involved). Furthermore, key knowledge gaps are identified and future research needs are proposed to address the potential challenges encountered in practical application of the Mn(VII)/bisulfite oxidation technology.
近年来，亚硫酸氢盐激活高锰酸盐（MnO；Mn(VII)）工艺作为一种新型的高级氧化技术，因其能够有效破坏水中的有机污染物，而受到了广泛关注。然而，由于该体系涉及的化学过程较为复杂，关于其潜在的反应机理和反应物种的争议持续了很长时间。本文旨在对 Mn(VII)/亚硫酸氢盐体系的科学发展进行综述，重点介绍了各种反应中间体的生成和贡献。研究表明，具有氧化作用的反应性锰物种（RMnS）（即可溶性 Mn(III)、Mn(V)和 Mn(VI)）和自由基物种（主要是 SO）是 Mn(VII)/亚硫酸氢盐体系增强有机污染物降解的主要氧化剂。亚硫酸氢盐在生成反应性中间体方面起着双重作用，既能作为激活剂，又能作为络合剂来稳定 RMnS。溶液化学（例如，[Mn(VII)]/[亚硫酸氢盐]摩尔比、溶液 pH 值、污染物类型、配体和水基质成分）对 RMnS 和自由基的生成和消耗有很大的影响，从而影响有机物的降解动力学和途径。特别是，溶解氧（DO）是推动有机物氧化的重要因素，因为 DO 的缺乏会阻止 SO 的生成，同时使过量的 SO 作为强还原剂消耗 RMnS。有趣的是，高铁酸盐（FeO，Fe(VI)）和六价铬（CrO/HCrO，Cr(VI)）作为类似于 Mn(VII)的高价金属含氧酸盐，也可以通过类似的途径被亚硫酸氢盐激活（即涉及高价金属-氧中间体和反应性自由基）。此外，本文还确定了关键的知识空白，并提出了未来的研究需求，以解决在实际应用中遇到的潜在挑战。
