Competition and regulation of radical vs. non-radical pathways in iron-activated peracetic acid systems

Abstract

With the escalating severity of environmental pollution, the development of efficient and controllable advanced oxidation technologies for the removal of organic pollutants in water has become a major focus in environmental remediation research. Peracetic acid (PAA), due to its high operational safety, environmental friendliness, and mild reaction conditions, has shown promising application prospects in wastewater treatment. Iron, as a common transition metal, has attracted extensive attention due to its activation capability in PAA systems. In particular, the competition and regulation mechanisms between radical and non-radical pathways formed under different iron valence states have become key areas of investigation. This review provides a systematic overview of the reaction pathways in iron-activated PAA systems. It first elucidates the reaction process between iron and PAA and the generation mechanisms of major reactive species, including hydroxyl radicals, peracetyl radicals, and non-radical oxidizing species. It then focuses on the competitive relationships between radical and non-radical pathways and the factors influencing their regulation. Furthermore, it analyzes the characteristics and patterns of different reactive species in terms of pollutant degradation efficiency, mineralization degree, and reaction selectivity. Finally, the review summarizes current strategies for enhancing the reactivity of PAA systems, such as structural optimization of iron-based catalysts, synergistic regulation by additives, and reinforcement of reaction conditions. These insights provide a theoretical foundation and technical reference for the future development of efficient and controllable PAA-based oxidation systems.