Catalytic oxidation processes for removing dimethylsulfoxide from wastewater

An effective method for removing dimethylsulfoxide (DMSO) from wastewater, based on the mild selective catalytic sulfoxidation with H2O2, is proposed in this study. The catalysts are W-containing layered double hydroxides (LDH), and they were obtained by ionic exchange of the nitrate anions from MAl-LDH precursors (M = Mg2+ or Zn2+) with both WO42- and W7O246- species. Results of X-ray diffraction (XRD), N2 adsorption, thermal gravimetric analysis (TGA), diffuse reflectance ultraviolet spectroscopy (DRUV) and Raman spectroscopy confirmed the formation of the W-oxospecies inside the interlayer space and the modification of the textural properties upon the exchange process. All catalysts showed very good activity and stability in the DMSO conversion into dimethylsulfone with dilute H2O2 aqueous solution, at low temperatures (20–50 °C). The efficiency of the H2O2 was higher than 95% and the behaviour of the water as solvent was very close to that of the organic solvents (ethanol, acetonitrile, 1,4-dioxane).