Efficient heterogeneous activation of peroxymonosulfate by facilely prepared Co/Fe bimetallic oxides: Kinetics and mechanism

The contamination issue caused by the antibiotics is now a big challenge due to its great potential hazardous to the human beings. Herein, three Co/Fe bimetallic oxides were synthesized for the activation of peroxymonosulfate (PMS) to degrade norfloxacin. The elemental analysis results confirmed the stoichiometric ratio of Fe/Co was 1.02, 2.03, and 6.65 (CoFe2O4·CoOx, CoFe2O4, Co0.4Fe2.6O4), respectively. The normalized pseudo-first-order kinetic rate constant (kapp) of Co0.4Fe2.6O4 was 0.18 L/(m2·min), which was over 10 times higher than those of CoFe2O4·CoOx (0.010 L/(m2·min)) and CoFe2O4 (0.012 L/(m2·min)). The degradation process would be further accelerated under weak basic condition (pH = 8.5). The enhanced surface hydroxyl groups were found to be the probable reason for the higher efficiency through the XPS analysis. Moreover, the sulfate radical rather than hydroxyl radical dominated the degradation process in the developed Co0.4Fe2.6O4/PMS system. Overall, the magnetic Co/Fe bimetallic oxide catalyst prepared in this study could be served as a high-quality candidate for the catalytic oxidation of refractory organic pollutants.