Unexpected side reactions dominate the oxidative transformation of aromatic amines in the Co(II)/peracetic acid system

• Published in: PNAS nexus Vol. 3; no. 2; p. pgae040
• Main Authors: Wu, Jing-Hang, Yang, Tian-Hao, Chen, Fei, Yu, Han-Qing
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 01.02.2024
• Subjects: Acetic acid; Acetylation; Acids; Amines; Aromatic compounds; By products; Byproducts; Catalytic oxidation; Chemical oxygen demand; Chemical properties; Chemical research; Cobalt; Contaminants; Degradation; Dimerization; Environmental hazards; Industrial applications; Microwave heating; Mineralization; Nitration; Nitrosation; Oxidation resistance; Oxidation-reduction reaction; Peracetic acid; Physical Sciences and Engineering; Pollutants; Ring opening; Side reactions; Toxicity; Wastewater treatment; United States; oxidative coupling; aromatic amines; Co–OOC(O)CH; toxic by-products; complex; peracetic acid; Co–OOC(O)CH3 complex
• ISSN: 2752-6542; 2752-6542
• DOI: 10.1093/pnasnexus/pgae040

Abstract Aromatic amines (AAs), ubiquitous in industrial applications, pose significant environmental hazards due to their resistance to conventional wastewater treatments. Peracetic acid (PAA)-based advanced oxidation processes (AOPs) have been proposed as effective strategies for addressing persistent AA contaminants. While the organic radicals generated in these systems are believed to be selective and highly oxidative, acetate residue complicates the evaluation of AA removal efficiency. In this work, we explored transformation pathways of AAs in a representative Co(II)-catalyzed PAA system, revealing five side reactions (i.e. nitrosation, nitration, coupling, dimerization, and acetylation) that yield 17 predominantly stable and toxic by-products. The dominant reactive species was demonstrated as Co–OOC(O)CH3, which hardly facilitated ring-opening reactions. Our findings highlight the potential risks associated with PAA-based AOPs for AA degradation and provide insights into selecting suitable catalytic systems aimed at efficient and by-product-free degradation of pollutants containing aromatic –NH2.