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

Abstract The feasibility of pollutant removal in aqueous solution by dielectric barrier discharge plasma in combination with Bi 2 WO 6 -rMoS 2 composite photocatalyst was investigated by choosing sulfamethoxazole (SMZ) as the model pollutant. In this study, Bi 2 WO 6 -rMoS 2 catalysts were synthesized by a modified hydrothermal method and characterized by TEM, XRD, XPS. The results showed that the Bi 2 WO 6 was well loaded on the surface of MoS 2 . The influences of the main operating parameters including discharge voltage, initial concentration, initial pH, mass ratios and dosages of Bi 2 WO 6 -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 Bi 2 WO 6 -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, Bi 2 WO 6 -rMoS 2 (1 wt%) still remained high removal efficiency of SMZ. Moreover, the yields of hydrogen peroxide (H 2 O 2 ) and Ozone (O 3 ) in plasma discharge process were also investigated, and the results exhibited that adding Bi 2 WO 6 -rMoS 2 could notably influence the amount of O 3 and H 2 O 2 . Finally, ten intermediates of SMZ degradation were identified, and the proposed SMZ degradation pathways were deduced based on the detected intermediates.