Microwave-induced dual-responsive spinel (CoxMn1-xFe2O4) target-triggered non-radical pathways of peroxymonosulfate: Superexchange interaction and synergistic mechanism

The efficient activation of peroxymonosulfate (PMS) and the directional selection of oxidation pathways are crucial for achieving efficient pollutant removal in advanced oxidation processes (AOPs). A composite activation method of a microwave-induced dual-responsive catalyst (Co0.4Mn0.6Fe2O4) with both dielectric and catalytic properties is proposed to successfully trigger the non-radical pathway of PMS for 100 % removal of pharmaceutical pollutant (diatrizoate, DTZ) in 6 min, which shows good resistance to environmental interference and cyclic stability, and lower electrical energy requirement. 1O2 and surface-bound reactive oxygen species (ROS) are the main ROSs responsible for non-radical oxidation, with a total contribution of 98 %. The superexchange effect of Co-Mn (Mn3++Co3+→Mn4++Co2+) induces the electron delocalization of Mn site, which promotes the adsorption of PMS, interfacial charge transfer, and surface-bound ROS generation. The "thermal and non-thermal" effects of microwaves accelerate electron transfer and 1O2 generation to further trigger non-radical pathways. This work provides new strategies for bifunctional catalyst design and directional triggering of non-radical pathways of PMS-AOPs.