Enhanced oxidation of organic contaminants by Mn(VII)/CaSO3 under environmentally relevant conditions: Performance and mechanisms
Enhanced oxidation of organic contaminants by Mn(VII)/CaSO3 under environmentally relevant conditions: Performance and mechanisms
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Mn(VII)/CaSO3 在环境相关条件下增强有机污染物的氧化：性能和机制
DOI：
10.1016/j.watres.2020.116481
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发表时间：
2021
期刊：
影响因子：
12.8
通讯作者：
Guan Xiaohong
中科院分区：
文献类型：
--
作者：
Rao D;an;Chen Jie;Dong Hongyu;Qiao Junlian;Zhou Baoxue;Sun Yuankui;Guan Xiaohong
尽管亚硫酸钠 (Mn(VII)/Na2SO3) 活化高锰酸盐在快速消除有机污染物方面显示出巨大潜力，但碱性条件下有限的反应活性和不良的锰残留可能会阻碍其广泛应用。为了解决这些挑战，本研究采用亚硫酸钙 (CaSO3) 作为 SO32−/HSO3−(S(IV)) 的缓释源来激活 Mn(VII)。结果发现，CaSO3固体的应用可以将Mn(VII)/S(IV)的有效工作pH范围从≤7.0扩大到≤9.0。此外，由于Ca2+的存在增强了MnO2的沉淀，在Mn(VII)/CaSO3体系中实现了非常低的Mn残留(<0.05 mg/L)。 Mn(VII)/CaSO3体系在反应动力学和活性氧化剂方面是一种独特的两阶段氧化过程。具体而言，Mn(VII) 被快速消耗，并在第一阶段产生反应性 Mn 中间体（例如 Mn(VI)、Mn(V)）、SO4•− 和 H2O•。然而，第二阶段由MnO2 和S(IV) 之间的相互作用控制，其中SO4•− 和HO• 作为主要的反应氧化剂。利用自动滴定仪，发现过量的 S(IV) 会极大地淬灭生成的自由基，而不会导致活性锰物质的大量消耗。所有这些结果增进了我们对Mn(VII)/S(IV)过程的理解，从而促进其应用。
Although permanganate activation by sodium sulfite (Mn(VII)/Na2SO3) has shown great potential for rapid abatement of organic contaminants, the limited reactivity under alkaline conditions and undesirable Mn residual may prevent its widespread application. To solve these challenges, calcium sulfite (CaSO3) was employed as a slow-release source of SO32−/HSO3−(S(IV)) to activate Mn(VII) in this study. It was found that the application of CaSO3solid could extend the effective working pH range of Mn(VII)/S(IV) from ≤7.0 to ≤9.0. Moreover, due to the enhanced precipitation of MnO2with the presence of Ca2+, very low Mn residual (<0.05 mg/L) was achieved in Mn(VII)/CaSO3system. Mn(VII)/CaSO3system is a unique two-stage oxidation process in terms of reaction kinetics and reactive oxidants. Specifically, Mn(VII) was rapidly consumed and reactive Mn intermediates (e.g., Mn(VI), Mn(V)), SO4•−, and HO•were produced in the first stage. However, the second stage was governed by the interaction between MnO2and S(IV), with SO4•−and HO•serving as the dominant reactive oxidants. Taking advantage of an automatic titrator, excess S(IV) was found to greatly quench the generated radicals, whereas it did not cause a significant consumption of reactive Mn species. All these results improved our understanding of the Mn(VII)/S(IV) process and could thus facilitate its application.