Mn2O3 作为过氧单硫酸盐和有机污染物之间的电子穿梭：表面活性 Mn(IV) 物种的主要作用,Environmental Science & Technology

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Mn2O3 作为过氧单硫酸盐和有机污染物之间的电子穿梭：表面活性 Mn(IV) 物种的主要作用
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2022-03-17 , DOI: 10.1021/acs.est.1c08790
Hongchao Li ₁ , Na Yuan ₁ , Jieshu Qian _{1,

2} , Bingcai Pan ₂

Affiliation

环境友好的锰氧化物在有机污染物的转化中起着至关重要的作用，要么通过催化分解氧化剂，例如过氧单硫酸盐 (PMS)，要么通过直接氧化目标污染物。由于它们的双重作用和复杂的表面化学反应，Mn 氧化物催化的 PMS 活化过程所涉及的机制仍然不清楚。在这里，我们通过分离PMS活化和污染物氧化过程，清楚地阐明了Mn ₂ O ₃催化PMS活化过程的机理。锰₂ O ₃作为穿梭介导电子从有机底物转移到 PMS，伴随着表面 Mn(IV)/Mn(III) 的氧化还原循环。多项实验结果表明，PMS与Mn ₂ O ₃表面结合形成内球络合物，然后分解形成长寿命的表面活性Mn(IV)物种，不产生硫酸根(SO ₄^{• –} ) 和羟基自由基 (HO ^• )。表面活性 Mn(IV) 物种被认为是降解有机污染物（例如苯酚）和形成单线态氧 ( ¹ O ₂ ) 的原因，然后是 Mn 上的表面 Mn(III) 位点的再生。₂ O₃ . 这项研究促进了对过渡金属氧化物催化的 PMS 活化过程所涉及的潜在机制的基本理解。

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Mn2O3 as an Electron Shuttle between Peroxymonosulfate and Organic Pollutants: The Dominant Role of Surface Reactive Mn(IV) Species

The environmentally benign Mn oxides play a crucial role in the transformation of organic contaminants, either through catalytically decomposing oxidants, e.g., peroxymonosulfate (PMS), or through directly oxidizing the target pollutants. Because of their dual roles and the complex surface chemical reactions, the mechanism involved in Mn oxide-catalyzed PMS activation processes remains obscure. Here, we clearly elucidate the mechanism involved in the Mn₂O₃ catalyzed PMS activation process by means of separating the PMS activation and the pollutant oxidation process. Mn₂O₃ acts as a shuttle that mediates the electron transfer from organic substrates to PMS, accompanied by the redox cycle of surface Mn(IV)/Mn(III). Multiple experimental results indicate that PMS is bound to the surface of Mn₂O₃ to form an inner-sphere complex, which then decomposes to form long-lived surface reactive Mn(IV) species, without the generation of sulfate radicals (SO₄^•–) and hydroxyl radicals (HO^•). The surface reactive Mn(IV) species are proposed to be responsible for the degradation of organic contaminants (e.g., phenol) and the formation of singlet oxygen (¹O₂), followed by the regeneration of the surface Mn(III) sites on Mn₂O₃. This study advances the fundamental understanding of the underlying mechanism involved in transition metal oxide-catalyzed PMS activation processes.

更新日期：2022-03-17

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