Highly stable Fe/γ-Al₂O₃ catalyst for catalytic wet peroxide oxidation

BACKGROUND: A highly stable Fe/γ-Al₂O₃ catalyst for catalytic wet peroxide oxidation has been studied using phenol as target pollutant. The catalyst was prepared by incipient wetness impregnation of γ-Al₂O₃ with an aqueous solution of Fe(NO₃)₃· 9H₂O. The influence of pH, temperature, catalyst and H₂O₂ doses, as well as the initial phenol concentration has been analyzed. RESULTS: The reaction temperature and initial pH significantly affect both phenol conversion and total organic carbon removal. Working at 50 °C, an initial pH of 3, 100 mg L⁻¹ of phenol, a dose of H₂O₂ corresponding to the stoichiometric amount and 1250 mg L⁻¹ of catalyst, complete phenol conversion and a total organic carbon removal efficiency close to 80% were achieved. When the initial phenol concentration was increased to 1500 mg L⁻¹, a decreased efficiency in total organic carbon removal was observed with increased leaching of iron that can be related to a higher concentration of oxalic acid, as by-product from catalytic wet peroxide oxidation of phenol. CONCLUSION: A laboratory synthesized γ-Al₂O₃ supported Fe has shown potential application in catalytic wet peroxide oxidation of phenolic wastewaters. The catalyst showed remarkable stability in long-term continuous experiments with limited Fe leaching, < 3% of the initial loading. Copyright