Effectiveness of metal oxide catalysts for the degradation of 1,4-dioxane

1,4-dioxane, commonly used as a solvent stabilizer and industrial solvent, is an environmental contaminant and probable carcinogen. In this study, we explored the concept of using metal oxides to activate H(2)O(2) catalytically at neutral pH in the dark for 1,4-dioxane degradation. Based on batch kinetics measurements, materials that displayed the most suitable characteristics (high 1,4-dioxane degradation activity and high H(2)O(2) consumption efficiency) were ZrO(2), WO(x)/ZrO(2), and CuO. In contrast, materials like TiO(2), WO(3), and aluminosilicate zeolite Y exhibited both low 1,4-dioxane degradation and H(2)O(2) consumption activities. Other materials (e.g., Fe(2)O(3) and CeO(2)) consumed H(2)O(2) rapidly, however 1,4-dioxane degradation was negligible. The supported metal oxide WO(x)/ZrO(2) was the most active for 1,4-dioxane degradation and had higher H(2)O(2) consumption efficiency compared to ZrO(2). In situ acetonitrile poisoning and FTIR spectroscopy results indicate different surface acid sites for 1,4-dioxane and H(2)O(2) adsorption and reaction. Electron paramagnetic resonance measurements indicate that H(2)O(2) forms hydroxyl radicals (˙OH) in the presence of CuO, and unusually, forms superoxide/peroxyl radicals (˙O(2)(−)) in the presence of WO(x)/ZrO(2). The identified material properties suggest metal oxides/H(2)O(2) as a potential advanced oxidation process in the treatment of 1,4-dioxane and other recalcitrant organic compounds.