Degradation of sulfamethoxazole in aqueous solution by dielectric barrier discharge plasma combined with Bi2WO6-rMoS2 nanocomposite: Mechanism and degradation pathway

The feasibility of pollutant removal in aqueous solution by dielectric barrier discharge plasma in combination with Bi2WO6-rMoS(2) composite photocatalyst was investigated by choosing sulfamethoxazole (SMZ) as the model pollutant. In this study, Bi2WO6-rMoS(2) catalysts were synthesized by a modified hydrothermal method and characterized by TEM, XRD, XPS. The results showed that the Bi2WO6 was well loaded on the surface of MoS2 . The influences of the main operating parameters including discharge voltage, initial concentration, initial pH, mass ratios and dosages of Bi2WO6-rMoS(2) on the removal efficiency of SMZ were studied. The results revealed that the initial concentration of 20 mg L(-1 )SMZ solution (100 mL) could be degraded by 97.6% with the addition of 0.08 g L-1 Bi2WO6-rMoS(2) (1 wt%) at 9 kV after 21 min, compared with 72.5% by single dielectric barrier discharge plasma. Even after four cycling runs, Bi2WO6-rMoS(2) (1 wt%) still remained high removal efficiency of SMZ. Moreover, the yields of hydrogen peroxide (H2O2) and Bi2WO6-rMoS(2) Ozone (O-3) in plasma discharge process were also investigated, and the results exhibited that adding could notably influence the amount of O-3 and H2O2. Finally, ten intermediates of SMZ degradation were identified, and the proposed SMZ degradation pathways were deduced based on the detected intermediates. (C) 2019 Elsevier Ltd. All rights reserved.