The critical role of minerals in persulfate-based advanced oxidation process: Catalytic properties, mechanism, and prospects

The severity of environmental pollution poses a serious threat to human health, and especially organic pollution is more complex and difficult to treat compared to heavy metal pollution. Nowadays, the persulfate-based advanced oxidation processes receive more and more attention due to high efficiency, strong controllability, easy operation, and economic competitiveness, which is generally employed for the efficient degradation of organic contaminants. Natural minerals possess the characteristics of low-cost, easy availability, environmental friendliness, non-toxic, special structural effects, etc., which have played a critical role and could be the promising alternative to traditional catalysts for persulfate activation. First, this review retrospects the research status of natural minerals and mineral-based catalysts for persulfate activation to degrade organic contaminants, i.e., pyrite, mackinawite, copper sulfide, kaolinite, and montmorillonite. Then, the mechanisms of persulfate activation by natural minerals and mineral-based catalysts to generate the reactive oxygen species including SO4•−, •OH, •O2−, 1O2, and surface reactive complex for contaminants degradation are systematically summarized. Finally, we discussed the further application of natural minerals in activating persulfate as well as the future research frontiers for practical environmental remediation, i.e., the synthesis and characterization of mineral-based catalysts dominated by non-radical pathway, the large-scale application of PDS with low-cost, the surface modification of mineral-based catalysts with amphiphilicity, as well as the more efficient catalysts possessing nano-restricted domain catalytic effect. The development and expansion of novel and efficient mineral-based catalysts with enhanced synergistic effects would provide new opportunities for persulfate activation in environmental remediation.