Since environmental pollution by emerging organic contaminants is one of the most important problems, gaining ground year after year, the development of decontamination technologies of water systems is now imperative. Advanced oxidation processes (AOPs) with the formation of highly reactive radicals can provide attractive technologies for the degradation of organic pollutants in water systems. Among several AOPs that can be applied for the formation of active radicals, this review study focus on sulfate radical based-AOPs (SR-AOPs) through the heterogeneous catalytic activation of persulfate (PS) or peroxymonosulfate (PMS) using perovskite and spinel oxides as catalysts. Perovskites and spinels are currently receiving high attention and being used in substantial applications in the above research area. The widespread use of these materials is based mainly in the possibilities offered by their structure as it is possible to introduce into their structures different metal cations or to partially substitute them, without however destroying their structure. In this way a battery of catalysts with variable catalytic activities can be obtained. Due to the fact that Co ions have been reported to be one of the best activators of PMS, special emphasis has been placed on perovskite/spinel catalysts containing cobalt in their structure for the degradation of organic pollutants through heterogeneous catalysis. Among spinel materials, spinel ferrites (MFe2O4) are the most used catalysts for heterogeneous activation of PMS. Specifically, catalysts with cobalt ion in the A position were reported to be more efficient as PMS activators for the degradation of most organic pollutants compared with other transition metal catalysts. Substituted or immobilized catalysts show high rates of degradation, stability over a wider pH area and also address better the phenomena of secondary contamination by metal leaching, thus an effective method to upgrade catalytic performance.

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Sulfate radical-based advanced oxidation processes (SR-AOPs) are lately applied for the degradation of various pollutants through the formation of reactive oxidant species (ROS) from activation of oxidants, such as persulfate (PS) or peroxymonosulfate (PMS). In this study, LaMO3 (M=Co, Fe, Cu, Mn, Ni) perovskite catalysts were synthesized, characterized by several techniques, and tested for the activation of persulfate towards the degradation of phenolic pollutants. The effect of substitution of position B of La-based perovskites as well as calcination temperature was studied. Overall, the results showed that the decisive role in the catalytic activity was the presence of structures that enhance the transfer of electrons between perovskite and oxidant. LaNiO3 followed by LaCoO3 were found as the most active catalysts. Finally, the stability of the catalysts was studied, showing that B-metal leaching is significant for both catalysts, with LaCoO3 being the most stable one.