Modulation synthesis of multi-shelled cobalt-iron oxides as efficient catalysts for peroxymonosulfate-mediated organics degradation

Simple-controlled synthesis of multiple porous and monodisperse cobalt-iron oxides were realized by varying the prepared conditions via a template-assisted glycol solvothermal process. The obtained materials were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Mossbauer spectroscopy and nitrogen adsorption/desorption measurement. It was found that the amounts of metal precursors and the Co:Fe ratio significantly influenced the morphology, the crystallinity, as well as the textural and electronic properties of the cobalt-iron products. The different cobalt-iron oxides with various shells were employed into the catalytic activation of peroxymonosulfate (PMS) for Orange II degradation, among which, multishelled cobalt ferrite microsphere was certified to perform the best activity due to the coefficient contribution of higher content of octahedral Co2+, more exposed active sites and the reservoir effect. Sulfate and hydroxyl radicals were crucial reactive species in Orange II degradation, proved by the scavenger quenching test. This work shows that cobalt-iron oxide microspheres with such architecture make differences in the PMS-mediated aqueous organics degradation system, which extends the perspective and application of such functional oxides in the environmental field.