Three-dimensional electro-Fenton degradation of ciprofloxacin catalyzed by CuO doped red mud particle electrodes: Electrodes preparation, kinetics and mechanism

In this present study, a series of CuO doped red mud (CuO/URM) particle electrodes with different CuO doping contents were prepared by physical impregnation method with ultrasonic assistance, and applied in a three-dimensional electro-Fenton (3D/EF) system for ciprofloxacin degradation. The synthesized CuO/URM particle electrodes were characterized by SEM, EDS, TEM, HRTEM, XRD, BET, XPS and EIS. It was found that the prepared CuO/URM particle electrode has excellent mesopore structure and high specific surface area, and the CuO doping could effectively reduce the resistance of particle electrode and accelerate the electron transfer. The results of comparison experiment, capture of active species experiment, ESR analysis and XPS analysis showed that the high electrocatalytic activity of the 3D/EF system was due to the combined effects of adsorption by particle electrode, direct oxidation from both anode and CuO/URM particle electrode, and indirect oxidation by active species generated in the system, and the possible catalytic mechanisms in the 3D/EF system catalyzed by 0.1CuO/URM was proposed. All results demonstrated that the 3D/EF system catalyzed by CuO/URM particle electrodes is a reliable technology for the disposal of CIP wastewater.