Preparation of SnOx-MnOx@Al2O3 for Catalytic Ozonation of Phenol in Hypersaline Wastewater

ABSTRACT The catalytic ozonation process (COP) is an effective and advanced oxidation technology for the treatment of organic wastewater. However, high salinity has a negative impact on catalytic ozonation performance. In this work, tin oxide (SnOx) and manganese oxide (MnOx) doped γ-Al2O3 catalysts (SnOx-MnOx@Al2O3) were prepared by the incipient wetness impregnation method and characterized by SEM, XRD, BET, XRT, XPS and FT-IR techniques. The SnOx-MnOx@Al2O3 catalyst was applied to the catalytic ozonation of phenol in hypersaline wastewater, and the catalytic performance was evaluated by COD removal efficiency. When the mass ratio of MnOx to SnOx was 1:3, the pH was 7, the catalyst dosage was 40 g/L, the ozone dosage was 6 mg/(L·min), the NaCl concentration was 15 g/L and the COD removal efficiency of hypersaline phenol wastewater reached 93.8% after 240 min of catalytic ozonation treatment. Compared with the single ozonation process (SOP), the introduction of SnOx-MnOx@Al2O3 catalyst improved the COD removal efficiency by 32.3%. Cl− may quench surface •OH species and ozone to form Cl• and Cl2•− with low activity and high selectivity, resulting in the reduction of catalytic ozonation efficiency. The catalytic activity of the SnOx-MnOx@Al2O3 catalyst remained high after eight cycles. In conclusion, the SnOx-MnOx@Al2O3 catalytic ozonation system exhibits efficient and stable mineralization performance and is a promising strategy for the treatment of hypersaline organic wastewater.