Comprehensive insight into heterogeneous persulfate activation for environmental pollutants degradation: Approaches and mechanism

The heterogeneous activation of persulfate-based advanced oxidation processes (persulfate AOPs) has been defined as potential wastewater treatment methods due to their excellent chemical reactivity. However, the reaction mechanisms of these processes are extremely intricate because of the simultaneous participation of many substances from the solid, liquid, and even gas phases. The development of novel active catalysts is hindered due to divergent mechanisms and deficient research techniques. In this review, the up-to-date development of heterogeneous catalyst category, catalytic characteristics, and reaction mechanism are comprehensively discussed. Essentially, the detection of persulfate, the identification of reactive oxygen species, and the evolution and analysis of organic oxidation pathways are reviewed, highlighting the innovation integration experimental/theoretical protocol to reveal the reaction mechanism in a future study. Finally, the limitations and possible breakthrough directions of persulfate AOPs were discussed, including the further study of the internal reaction mechanism in persulfate AOPs, the requirement of reasonable evaluation of the treatment effect, and the feasibility of full-scale application.