Catalytic Ozonation of Reactive Red 195 in Aqueous Solution over a Cobalt/Aluminum Oxide-Ceria Catalyst

Abstract

The textile industry has become one of the largest producers of water pollution. The azo dyes used in the textile industry may present a serious environmental problem because of their high toxicity and chemical stability. In the present work, the cobalt/aluminum oxide-ceria (Co/Al2O3-CeO2) catalyst was synthesized, and the degradation of Reactive Red 195 (RR195) by catalytic ozonation was studied. The Co/Al2O3-CeO2 catalyst was synthesized via the incipient wetness method with the assistance of ultrasound. The presence of Co/Al2O3-CeO2 did not notably improve the degradation of RR195 compared to ozonation alone, but it was advantageous for RR195 mineralization. The effects of initial dye concentration (200–800 mg/L), catalyst dosage (1–4 g/L), and solution pH (4–10) on color, and COD removal were evaluated. The results indicate that the dye’s concentration significantly affects COD removal efficiency. The optimum catalyst dosage and pH values were determined to be 3 g/L and 8, respectively. Co/Al2O3-CeO2 catalyst shows good catalytic activity and stability based on four repeated tests during RR195 ozonation. Finally, a possible mechanism and a kinetic scheme of the catalytic ozonation of RR195 were proposed.