Catalytic activation of PS/PMS over Fe-Co bimetallic oxides for phenol oxidation under alkaline conditions

In this study, we compared the differences between bimetallic oxides FeCo 2 O 4 catalyzing the oxidation of phenol by peroxydisulfate (PS) and peroxymonosulfate (PMS) under near neutral and alkaline conditions. Phenol could be completely oxidized and removed in both PMS and PS systems. X-ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT) calculations showed that there was a synergistic mechanism between Co and Fe on the catalyst surface. Although the PMS-FeCo 2 O 4 system reached the fastest reaction rate of 1.5 × 10 −1 min −1 , it showed a higher oxidants consumption and more residual total organic carbon (TOC) (36%) in solutions after reactions. Quenching experiments and electron paramagnetic resonance (EPR) analysis showed that sulfate radical (SO 4 − ), hydroxyl radical ( OH) and singlet oxygen ( 1 O 2 ) played important roles in the oxidation of phenol in PMS system. While in the PS-FeCo 2 O 4 system, in addition to free radical reactions, the non-radical mechanisms between PS and the catalyst surface played a major role in phenol oxidation, and the soluble organic matter in the PS system could be completely removed. Thus, PS has a better application prospect in the treatment of phenol. This discovery has certain guiding significance for catalyst modification and doping to improve catalyst activity and the choice of oxidant.