Boosting hydrogen peroxide activation for the high-efficient removal of volatile dimethylsulfoxide over niobium-based catalysts

Abstract

Dimethyl sulfoxide (DMSO) is an important solvent in numerous industries. The biodegrading process of DMSO is slow and produces toxic volatile compounds including CH3SCH3, CH3SH, and H2S. Hence, it is important to develop chemical methods for treating DMSO-containing wastewater. In the present work, niobium oxyhydroxide and niobium oxide were synthesized and used to activate hydrogen peroxide for the degradation of DMSO to DMSO2. The niobium oxyhydroxide catalyst exhibited much better catalytic activity for DMSO oxidation than niobium oxide. EPR spectra and radical scavenging experiments confirmed that O2•− and 1O2 are the main active species for the oxidation of DMSO. FTIR analysis and DFT calculation confirmed that the surface hydroxyl of niobium oxyhydroxide can be substituted by hydroperoxo group of H2O2 to form Nb−OOH group, which can directly oxidize DMSO or indirectly oxidize DMSO via O2•− and 1O2. However, H2O2 cannot form hydroperoxo group on the surface of niobium oxide, which might trigger the lower activity of niobium oxide catalysts than the niobium oxyhydroxide catalyst. The niobium oxyhydroxide catalyst exhibited good reusability and was promising for the treatment of DMSO-containing wastewater.