Efficient degradation of AO7 by ceria-delafossite nanocomposite with non-inert support as a synergistic catalyst in electro-fenton process

Abstract

CuFeO2/CeO2 as a novel catalyst was synthesized and its catalytic performance was evaluated for electro-Fenton degradation of acid orange 7 (AO7). It was demonstrated from the characterization results that the rhombohedral structure of CuFeO2 and face-centered cubic fluorite structure of CeO2 remained stable after nanocomposite construction. The impact of such operating parameters as pH, current intensity and, catalyst amount was investigated and the optimum conditions (100 mgL−1 AO7, pH 3, 150 mgL−1 CuFeO2/CeO2, I: 150 mA) determination led to 99.3% AO7 removal and 79.1% COD removal in 60 min. The introduction of CeO2 as non-inert support had a significant impact on H2O2 electro-generation as an important step in AO7 removal. CuFeO2/CeO2 presented negligible metal leaching (iron 4.13%, copper 2.4%, and cerium 0.33%) which could be due to the strong interaction between active species and support. The nanocomposite performed efficiently in salty systems and two samples of real wastewaters due to Brønsted acidity character of ceria, which makes it a potential choice in industrial applications. The good performance of nanocomposite could be the result of the synergistic effect between Fe, Cu, and Ce. Regarding scavenging measurements results, the electro-Fenton process followed the Haber-Weiss mechanism. The by-products detection was performed using GC-MS analysis to propose an acceptable pathway for EF degradation of AO7. The BMG kinetics model (1/b = 0.969 (min) and 1/m = 0.269 (min−1)) was matched with the experimental data and described the kinetics of reaction very well. The catalytic activity of CuFeO2/CeO2 almost remained after six cycles. Based on the obtained results, CuFeO2/CeO2 using the benefit of the synergistic effect of Ce3+ with Fe2+ and Cu+can be introduced as a promising novel catalyst for the electro-Fenton reaction in wastewater treatment.