Generation, Detection and Regulation Strategies of Reactive Species in Persulfate Activation Systems

Persulfate-based advanced oxidation processes (AOPs) have emerged as highly promising technologies for degrading recalcitrant organic pollutants due to their flexible activation pathways and the diverse range of reactive species generated. This review establishes a comprehensive framework that encompasses mechanistic generation pathways, identification methods, and regulation strategies of both radical and non-radical species. Through this framework, the review reveals several fundamental challenges that hinder practical application, including uncertainties in identifying dominant reactive species in complex matrices, the intricate influence of coexisting ions and natural organic matter, catalyst deactivation under long-term operation, and the lack of sustainable and scalable synthesis routes for high-performance catalysts. In response to these issues, the review finally provides recommendations, such as integrating various characterization methods, developing predictive kinetic and computational models, engineering structurally robust and environmentally benign catalysts, and incorporating machine-learning tools to guide rational catalyst design and pathway prediction. These strategies outline clear future directions for advancing persulfate-based AOPs toward practical implementation. Overall, this work offers a systematic and insightful foundation that not only deepens mechanistic understanding but also bridges the gap between laboratory discoveries and real-world water treatment applications.