Synergistic catalysis of tungsten disulfide and manganese ions for the degradation of dimethyl disulfide using chlorine dioxide

Abstract

Dimethyl disulfide (DMDS) is a typical odorant in chemical and pesticide-contaminated sites, characterized by low odor threshold and high volatility. In this study, a ClO2/Mn2+/WS2 catalytic system was constructed for the degradation of DMDS. Under the reaction conditions of 400 μm ClO2, 20 μm Mn2+, 80 μM WS2, and pH = 7.0, the residual rate of DMDS decreased to 10.58 % within 80 min. Analyses using XPS, FRSEM, XRD, and EDX confirmed the synergistic catalytic effect of WS2 and Mn2+. The cyclic valence states of Mn2+/Mn4+ and W4+/W6+ were identified as the primary factors enhancing ClO2 activation for DMDS degradation. WS2 maintained good catalytic activity even after four cycles, demonstrating excellent reusability. Furthermore, EPR testing and quenching experiments elucidated the main reactive oxygen species (ROS) during the reaction, including 1O2, OH, and ClO2. In the initial 10 min, the oxidation process was dominated by 1O2 (44.48 % rate contribution) and ClO2 (55.52 % rate contribution), while in the subsequent 70 min, OH (49.16 % rate contribution) and ClO2 (50.84 % rate contribution) played the primary role. DFT calculations combined with GC–MS detection were utilized to propose possible degradation pathways of DMDS. Various anions (HCO3−, Cl−, SO2 − 4, NO3−) and humic acid (HA) exhibited different degrees of inhibition on DMDS degradation in the ClO2/Mn2+/WS2 system. This study provides a feasible approach for efficiently removing DMDS in pesticide plants and chemical industrial parks.