Unraveling Different Reaction Characteristics of Alkoxy Radicals in a Co(II)-Activated Peracetic Acid System Based on Dynamic Analysis of Electron Distribution.
Environ Sci Technol
; 2024 Feb 05.
Article
en En
| MEDLINE
| ID: mdl-38315813
ABSTRACT
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 ESUMO. In comparison, CH3COOO⢠can react with sulfacetamide via a similar radical self-sacrificing bimolecular nucleophilic substitution (SN2) route owing to its high ESOMO 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.
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MEDLINE
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En
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Environ Sci Technol
Año:
2024
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Article