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.