Why does dissolved oxygen govern Mn(III) formation and micro-pollutant abatement in the permanganate/bisulfite process?
Why does dissolved oxygen govern Mn(III) formation and micro-pollutant abatement in the permanganate/bisulfite process?
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为什么溶解氧控制高锰酸盐/亚硫酸氢盐工艺中 Mn(III) 的形成和微污染物的消除？
DOI：
10.1016/j.cej.2019.123556
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发表时间：
2020-07
影响因子：
15.1
通讯作者：
Qiang Zhimin
中科院分区：
文献类型：
--
作者：
Dong Huiyu;Duan Shule;Liu Chao;Yuan Xiangjuan;Qiang Zhimin
过氧化氢/亚硫酸氢盐（PM/BS）工艺是一种新型的水/废水处理中微污染物的高级氧化降解工艺。15 s后，PM/BS对碘帕醇（IPM）、嗪草酮（MET）和苯酚的去除率分别为65%、>99%和> 99%，而单独使用PM或BS没有观察到明显的去除率。PM/BS工艺的这些加速降解归因于Mn（III）、硫自由基（SO 4·-）和羟基自由基（HO·）的形成。有趣的是，它被发现，溶解氧（DO）控制的PM/BS过程中的微污染物的减少。当DO为0.1 mg L−1时，所有测试的微污染物的脱氮率均<5%，显著低于9.1 mg L− 1 DO时的脱氮率（65%−99%）。此外，在PM/BS过程中的Mn（III）的形成表现出积极的依赖于DO消耗。通过电子顺磁共振和猝灭实验进一步发现，BS还原PM生成SO 3·−，SO 3·−可被DO氧化为SO 5·−。PM/BS工艺中[PM]：[BS]：[DO]的Mn（III）形成化学计量测定为1：5：1.5的比率。SO 5·−不仅促进了Mn（III）的生成，还促进了SO 4·−和HO·的生成，其中Mn（III）和SO 4·−主要对微污染物的降解起作用。特别是，本研究表明，PM/BS工艺中Mn（III）的生成途径不是Mn（VII）的直接还原，而是Mn（II）被SO 5·−氧化。同时，维持足够的DO是PM/BS工艺降解微污染物的必要条件。
Permanganate/bisulfite (PM/BS) process is a novel advanced oxidation process for degradation of micro-pollutants in water/wastewater treatment. The abatements of iopamidol (IPM), metribuzin (MET) and phenol by the PM/BS process after 15 s were 65%, >99% and >99%, respectively, while no obvious abatements were observed with PM or BS alone. These accelerated degradations by the PM/BS process were attributed to the formations of Mn(III), sulfur radical (SO4•−) and hydroxyl radical (HO•). Interestingly, it was found that dissolved oxygen (DO) governed the abatement of micro-pollutants in PM/BS process. When DO was around 0.1 mg L−1, the abatements of all tested micro-pollutants were <5%, significantly lower than those under 9.1-mg L−1DO (65%−99%). Moreover, the formation of Mn(III) in the PM/BS process exhibited a positive dependence on DO consumption. Via electron paramagnetic resonance and quenching experiments, it was further found that the reduction of PM by BS generated SO3•−, which could be oxidized by DO to SO5•−. The Mn(III) formation stoichiometry of [PM]:[BS]:[DO] in the PM/BS process was determined to be 1:5:1.5 ratio. SO5•−promoted the formations of not only Mn(III), but also SO4•−and HO•, among which Mn(III) and SO4•−mainly contributed to the degradation of micro-pollutants. Especially, this study illustrates that the formation pathway of Mn(III) in PM/BS process is not the direct reduction of Mn(VII), but the oxidation of Mn(II) by SO5•−. Meanwhile, maintaining enough DO is indispensable for the degradation of micro-pollutants by the PM/BS process.
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