Efficient degradation of tetracycline using core-shell Fe@Fe2O3-CeO2 composite as novel heterogeneous electro-Fenton catalyst

Developing efficient heterogeneous electro-Fenton (EF) catalysts for degradation of organic pollutants remains a challenge. Herein, a novel heterogeneous EF catalyst, core-shell Fe@Fe2O3-CeO2 composite, was successfully synthesized in a facile manner for effective degradation of tetracycline (TC) pollutant. The catalytic activity was evaluated by effects of different processes, Fe/Ce molar ratio, catalyst dosage, initial solution pH, applied current and aeration mode. Fe@Fe2O3-CeO2 with 2:1 Fe/Ce molar ratio achieved TC removal efficiency of 90.7% within 1 h and mineralization efficiency of 86.9% within 6 h with such excellent performance attributed to the high utilization efficiency of H2O2 and the synergistic effects between Ce4+/Ce3+ and Fe3+/Fe2+. Moreover, this novel catalyst exhibited good recyclability and stability in successive cycles with low metal leaching. Furthermore, the heterogeneous EF process showed satisfactory catalytic activity towards degradation of other organic pollutants (e.g., metronidazole, diclofenac sodium, and chloramphenicol). Based on the experimental results and analysis, the mechanism of the heterogeneous EF process with Fe@Fe2O3-CeO2 catalyst and possible TC degradation pathways were proposed, which provides insights into the catalytic reaction process and should be of value in facilitating the application of this method in refractory wastewater treatment.