Study on catalytic mechanisms of Fe3O4-rGOx in three typical advanced oxidation processes for tetracycline hydrochloride degradation

This study explored the catalytic mechanism and performance impacted by the materials ratio of Fe3O4-GOx composites in three typical advanced oxidation processes (AOPs) of O3, peroxodisulfate (PDS) and photo-Fenton processes for tetracycline hydrochloride (TCH) degradation. The ratio of GO in the Fe3O4-GOx composites exhibited different trends of degradation capacity in each AOPs based on different mechanisms. Fe3O4-rGO20wt% exhibited the optimum catalytic performance which enhanced the ozone decomposition efficiency from 33.48% (ozone alone) to 51.83% with the major reactive oxygen species (ROS) of O2•−. In PDS and photo-Fenton processes, Fe3O4-rGO5wt% had the highest catalytic performance in PDS and H2O2 decomposition for SO4•‒, and •OH generation, respectively. Compared with using PDS alone, PDS decomposition rate and TCH degradation rate could be increased by 5.97 and 1.73 times under Fe3O4-rGO5wt% catalysis. In the photo-Fenton system, Fe3O4-rGO5wt% with the best catalyst performance in H2O2 decomposition, and TCH degradation rate increased by 2.02 times compared with blank group. Meantime, the catalytic mechanisms in those systems of that the ROS produced by conversion between Fe2+/Fe3+ were also analyzed.