Degradation of Methylene Blue by Ozone Oxidation Catalyzed by the Magnetic MnFe<sub>2</sub>O<sub>4</sub>@Co<sub>3</sub>S<sub>4</sub> Nanocomposite
Tanxia Xiang, Dengjie Zhong, Yongxian Zhou, Yunlan Xu, Danli Tang, Wantao Li, Yuanfang Yang, Chunmiao Fan, Jisai Chen
Abstract
In this study, the MnFe 2 O 4 @Co 3 S 4 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 Co 3 S 4 made MnFe 2 O 4 grow uniformly on Co 3 S 4 nanosheets, which effectively prevented the agglomeration of MnFe 2 O 4 . Moreover, MnFe 2 O 4 provided active sites and Mn 3+ /Mn 2+ and Fe 3+ /Fe 2+ cycles for the ozone oxidation process. Not only did Co 3 S 4 provide the active site (Co 2+ /Co 3+ ) for the ozone oxidation process but also its derived S 2– /S 2 2– 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 MnFe 2 O 4 to Co 3 S 4 was 6:3 (MnFe 2 O 4 @Co 3 S 4 -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 1 O 2, O 2 . –, and ·OH. The MnFe 2 O 4 @Co 3 S 4 magnetic nanocomposite is an efficient and stable O 3 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.