Novel-structured Mo-Cu-Fe-O composite for catalytic air oxidation of dye-containing wastewater under ambient temperature and pressure

Abstract

AbstractA novel-structured Mo-Cu-Fe-O composite was successfully prepared by co-precipitation and impregnation method. The properties of the as-prepared samples were determined using X-ray diffraction, temperature-programmed reduction by H2, cyclic voltammetry, and temperature-programmed desorption by O2. The results showed that Mo6+ diffused into the Cu-Fe-O crystal lattice and then formed a new crystalline phase of CuMoO4. The Mo-Cu-Fe-O catalyst had redox properties, and its surface contained active sites for oxygen adsorption. In addition, the catalytic activity of the Mo-Cu-Fe-O composite was evaluated by the degradation of Cationic Red GTL, Crystal Violet, and Acid Red in catalytic wet air oxidation (CWAO) at ambient temperature and pressure. The Mo-Cu-Fe-O catalyst showed excellent activity at basic conditions for the degradation of Cationic Red GTL. High removal efficiencies of 91.5% and 92.8% were achieved for Cationic Red GTL and Crystal Violet, respectively, in wastewater, and the efficiency remained high after seven cycles. However, almost no degradation of Acid Red occurred in the CWAO process. Furthermore, hydroxyl radicals were formed in the CWAO process, which induced the decomposition of the two cationic dyes in wastewater, and the toxicity of their effluents was decreased after degradation. The results indicate that the Mo-Cu-Fe-O composite shows excellent catalytic activity for the treatment of wastewater contaminated with cationic dyes.