A novel magnetic heterogeneous catalyst oxygen-defective CoFe2O4-x for activating peroxymonosulfate

Through direct and indirect radical mechanism of peroxymonosulfate (PMS) activation, novel CoFe2O4-x catalysts were successfully developed via hydrogen calcination to overcome popular disadvantages of the dependence on pH. Bisphenol A (BPA) was selected as the model pollutant to decipher the mechanism of catalysts for peroxymonosulfate (PMS) activation. Possible degradation pathways of Bisphenol A were proposed via analysis of liquid chromatograph mass spectrometer (LC-MS). The findings indicated that catalytic activation of CoFe2O4-x was not dependent upon the initial pH, as the direct and indirect radicals seemed to be generated in parallel. FTIR analysis confirmed that surface hydroxyl groups were actively involved in the activation of PMS under alkaline conditions. During the reaction, the oxygen defects promoted electron transfer and participated in the redox cycle from Co3+/Fe3+ to Co2+/Fe2+ to generate O-1(2) and O-2 center dot(-). Hydroxyl (OH center dot) and sulfate (SO4 center dot(-)) radicals were generated on the surface of CoFe2O4-x by the synergistic interactions among oxygen defects, transition metal, and surface hydroxyl groups. To the best of our knowledge, this combined mechanism of direct and indirect radical generation for advanced oxidation was a first-attempt study to be disclosed in public domain.