<br>基于电子分布动态分析揭示 Co(II) 活化过乙酸体系中烷氧基自由基的不同反应特性,Environmental Science & Technology

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基于电子分布动态分析揭示 Co(II) 活化过乙酸体系中烷氧基自由基的不同反应特性
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2024-02-05 , DOI: 10.1021/acs.est.3c07977
Huixuan Zhang ₁ , Long Chen ₁ , Penghui Du ₁ , Fan Li _{1,

2} , Wen Liu _{1,

2,

3}

Affiliation

基于过氧乙酸（PAA）的高级氧化工艺（AOP）在有机废水处理中显示出广阔的应用前景。烷氧基包括CH ₃ COO ^•和CH ₃ COOO ^•是PAA-AOP 体系中的主要活性物质。然而，它们攻击有机污染物的反应机制仍存在争议。在本研究中，构建了中性pH下的Co(II)/PAA均相AOP系统来产生这两种烷氧基自由基，并探讨了它们与典型新兴污染物（磺胺醋酰胺）的不同反应机制。应用动态电子分布分析，深入揭示基于分子轨道分析的自由基介导反应机理。结果表明，氢原子夺取是CH ₃ COO ^•和CH ₃ COOO ^•攻击磺胺醋酰胺的最有利途径。然而，这两个自由基不能通过自由基加合物形成途径与磺胺醋酰胺反应。有趣的是，单电子转移反应仅对CH ₃ COO ^•有利，因为其E _SUMO较低。相比之下，CH ₃ COOO ^•由于其高E _SOMO且易于从过氧键中O 原子的n 轨道逃逸，因此可以通过类似的自由基自牺牲双分子亲核取代(S _N 2) 途径与磺胺醋酰胺反应。这些发现可以显着提高对CH ₃ COO ^•和CH ₃ COOO ^•在分子轨道水平上攻击有机污染物的反应性的认识。

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Unraveling Different Reaction Characteristics of Alkoxy Radicals in a Co(II)-Activated Peracetic Acid System Based on Dynamic Analysis of Electron Distribution

Peracetic acid (PAA)-based advanced oxidation processes (AOPs) have shown broad application prospects in organic wastewater treatment. Alkoxy radicals including CH₃COO^• and CH₃COOO^• are primary reactive species in PAA-AOP systems; however, their reaction mechanism on attacking organic pollutants still remains controversial. In this study, a Co(II)/PAA homogeneous AOP system at neutral pH was constructed to generate these two alkoxy radicals, and their different reaction mechanisms with a typical emerging contaminant (sulfacetamide) were explored. Dynamic electron distribution analysis was applied to deeply reveal the radical-meditated reaction mechanism based on molecular orbital analysis. Results indicate that hydrogen atom abstraction is the most favorable route for both CH₃COO^• and CH₃COOO^• attacking sulfacetamide. However, both radicals cannot react with sulfacetamide via the radical adduct formation route. Interestingly, the single-electron transfer reaction is only favorable for CH₃COO^• due to its lower E_SUMO. In comparison, CH₃COOO^• can react with sulfacetamide via a similar radical self-sacrificing bimolecular nucleophilic substitution (S_N2) route owing to its high E_SOMO and easy escape of unpaired electrons from n orbitals of O atoms in the peroxy bond. These findings can significantly improve the knowledge of reactivity of CH₃COO^• and CH₃COOO^• on attacking organic pollutants at the molecular orbital level.

更新日期：2024-02-05

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