Heterogeneous Peroxymonosulfate-Based Advanced Oxidation Mechanisms: New Wine in Old Bottles?

Heterogeneous persulfate-based advanced oxidation processes (PS-AOPs) have been gaining significant attention in water/wastewater treatment; however, the elucidation of mechanisms in PS-AOPs has become increasingly complex as the understanding of potential reactive pathways expands and the rigor of corresponding characterizations intensifies. As such, accurately illustrating system mechanisms with a robust and convincing methodology is crucial, while the influence of substrates must not be overlooked. In this Perspective, established techniques and critical issues are systematically compiled to serve as practical guidelines. Additionally, a newly proposed pathway, the direct oxidation transfer process (DOTP), is discussed in comparison to conventional mineralization processes by reactive oxidative species (ROS) in PS-AOPs. Overall, the investigation of PS-AOP mechanisms across various heterogeneous systems remains contentious and calls for standardization, for which this work aims to serve as a valuable reference.