Rapid Peracetic acid activation by CoO under neutral condition: The contribution of multiple reactive species

This paper proposes a novel process of cobalt monoxide (CoO)-activated peracetic acid (PAA) for treating emerging micropollutant in water. PAA was activated under neutral conditions by combining a dominant heterogeneous phase on the catalyst surface and a homogeneous phase by dissolved Co²⁺. The system produced several reactive oxygen species, including hydroxyl radicals (HO^∙HO^•), singlet oxygen (¹O₂), organic radicals (RO^•(CH₃C(O)O^•, CH₃C(O)OO^•) and high-valent cobalt (Co(IV)). Organic radicals and high-valent cobalt primarily drove the emerging micropollutants degradation, interacting via electron transfer. Further density functional theory calculations supported that the spontaneous adsorption of PAA onto the catalyst could break peroxy bonds that generate radicals. Furthermore, the CoO surface structure underwent minimal changes during the reaction, making it highly reusable. Thus, the novel CoO/PAA system could be an effective advanced oxidation process for water treatment.