Degradation of Methylene Blue by Ozone Oxidation Catalyzed by the Magnetic MnFeO@CoS Nanocomposite.

In this study, the MnFeO@CoS magnetic nanocomposite was prepared by a two-step hydrothermal method and used to catalyze the ozone oxidation degradation of methylene blue. It was characterized by XRD, EDS, SEM, FT-IR, and XPS. The results showed that the introduction of CoS made MnFeO grow uniformly on CoS nanosheets, which effectively prevented the agglomeration of MnFeO. Moreover, MnFeO provided active sites and Mn/Mn and Fe/Fe cycles for the ozone oxidation process. Not only did CoS provide the active site (Co/Co) for the ozone oxidation process but also its derived S/S accelerated the electron transfer rate on the surface of the material, thus improving the efficiency of catalytic ozone oxidation degradation of methylene blue. When the molar ratio of MnFeO to CoS was 6:3 (MnFeO@CoS-3), the catalytic ozone degradation efficiency of methylene blue was the best, which reached 93.55% in 12 min. The reactive oxygen species in catalytic ozonation degradation of MB were O, O, and ·OH. The MnFeO@CoS magnetic nanocomposite is an efficient and stable O activator, which maintains high catalytic activity and low metal ion leaching after five cycles, indicating that it has a good application prospect in catalyzing ozone oxidation to degrade organic pollutants.