Catalytic ozonation of toxic pollutants over magnetic cobalt-doped Fe3O4 suspensions

Magnetic cobalt-doped Fe3O4 (FeCo) was prepared using a co-precipitation method and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The catalyst showed high, stable catalytic activity for the degradation and mineralization of toxic persistent organic pollutants, as demonstrated with the herbicides 2,4-dichlorophenoxyacetic acid, 2,4-dichlorophenol, and 2,4,6-trichlorophenol and pharmaceutical phenazone in aqueous solution with ozone. FeCo was very effective at the mineralization of refractory oxalic acid produced in the degradation of organic compounds. The ozone was adsorbed on the surface of FeCo competing with water molecules in the aqueous phase, and converted into hydroxyl radical, meanwhile the catalyst surface underwent oxidation and reduction as demonstrated by in situ ATR-FTIR, CV and other experimental data obtained. Furthermore, the characterization studies indicated that the introduction of Co increased the rate of FeCo oxidation and reduction during the decomposition of ozone, enhancing the activity and stability of Fe3O4.

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► Magnetic cobalt-doped Fe3O4 showed high, stable activity for catalytic ozonation.
► A hydroxyl radical reaction mechanism was verified for catalytic ozonation on cobalt-doped Fe3O4.
► Ozone was found to adsorb on the catalyst surface competing with water molecules by in situ ATR-FTIR.
► The introduction of Co enhanced the interfacial electron transfer.