Efficient degradation of tetracycline: Performance and mechanism study of Fe3O4@CF composite electrode materials applied to a non-homogeneous photo-electro-Fenton process

In order to improve the low conversion efficiency of Fe2+ in conventional electro-Fenton, this work developed solvent-heated Fe3O4@carbon felt (Fe3O4@CF) electrodes, which have good photo-electrochemical characteristics. The structure, composition and photoelectrochemical properties of the electrode were analyzed by a series of characterization measurements. The loading of Fe3O4 on the carbon felt (CF) surface improves the agglomeration of Fe3O4, effectively increasing the active sites of the electrode reaction and also improving the photoelectrochemical properties of the electrode. The Fe3O4@CF electrode was applied to the photo-Fenton, electro-Fenton and non-homogeneous photo-electro-Fenton systems respectively, and the results showed that after 60 min reaction, the best tetracycline removal efficiency of Fe3O4@CF electrode in heterogeneous photo-electro-Fenton system is 97.8 %. Then, the influencing factors in the degradation of tetracycline in the non-homogeneous photo-electro-Fenton system were investigated. Fe3O4@CF electrode had good cycling stability as the removal rate of tetracycline in solution was still above 85 % after 5 cycles of stabilization experiments. Fe3O4@CF electrode had good mineralization effect and the removal rate of TOC in solution could reach 83.3 %. Finally, free radical quenching experiments were conducted to identify the active substances that play a major role in the reaction process, and the reaction mechanism of the non-homogeneous photo-electro-Fenton system for the degradation of tetracycline was proposed. In summary, it is shown that Fe3O4@CF electrode is of great significance for the application of non-homogeneous photo-electro-Fenton system for the degradation of organic wastewater.