Catalysis of MnO2-cellulose acetate composite films in DBD plasma system and sulfamethoxazole degradation by the synergistic effect

Herein, dielectric barrier discharge (DBD) plasma and MnO 2 -cellulose acetate (MnO 2 /CA) composite films was coupled together to degrade sulfamethoxazole (SMX) in water. The MnO 2 /CA composite films were firstly prepared successfully though heating blending method in this study and then characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectra, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TG). Catalytic effect of the MnO 2 /CA films was investigated by comparing the removal percentages, the kinetic constants, the energy utilization efficiencies ( G 50 ) as well as the COD and TOC removal during the SMX degradation in the DBD plasma system with or without the MnO 2 /CA films addition under different reaction conditions. The optimal catalytic performance was obtained by adding the 3% MnO 2 /CA films into the DBD plasma system and the alkaline solution condition was favorable for the SMX degradation. After four times using, the MnO 2 /CA composite films still maintained the catalytic activity. Catalytic mechanism of the MnO 2 /CA films was speculated by analyzing the changes of solution pH and conductivity during the reaction, concentrations of the formed O 3 and H 2 O 2 in water and the generated active species ( 1 O 2 and ·OH) in both the DBD plasma system and the DBD-MnO 2 /CA films system. The quenching test was also carried out to figure out the important effect of the ·O 2 − , 1 O 2 and ·OH for the SMX degradation in the synergistic system. Finally, LC-MS was used to analyze the main intermediates generated during the SMX degradation and the possible degradation pathways were accordingly speculated. The research could provide a new direction for the development and application of the DBD plasma technology as well we the composite films catalyst.