In situ generated iron oxide nanosheet on iron foam electrode for enhanced electro-Fenton performance toward pharmaceutical wastewater treatment

Electro-Fenton (EF) is considered to be an effective technology for the purification of organic wastewater containing antibiotics, but the construction of accessible and efficient heterogeneous EF catalytic materials still faces challenges. In this study, an iron foam-derived electrode (FeOx/if-400) was prepared by a simple method (chemical oxidation combined heat treatment). The fabricated electrode presented great EF degradation efficiency under wide pH range (almost completely removing 50 mg L-1 TNZ within 60 min) and maintained great stability after consecutive operation (>95% removal after six cycles). Also, the FeOx/if-400 electrode showed good purification ability for pharmaceutical wastewater as evaluated by the quadrupole time-of-flight mass spectrometry and the three-dimensional excitation-emission matrix fluorescence spectroscopy. Based on experimental results, characterization analysis, and density functional theory (DFT) calculations, the EF reaction mechanism of FeOx/if-400 electrode and the organics degradation pathways in simulated and real matrices were proposed. Significantly, the biotoxicity assessment of the degradation intermediate products was revealed by ECOSAR software and relative inhibition of E. coli, which fully proved the environmental friendliness of the EF process by the FeOx/if-400 cathode. This work provides a green and effective EF system, showing a promising application potential in the field of organic wastewater treatment containing antibiotic contaminants. The serious environmental concerns are gradually exerted with the rapid industrial development and population expansion, one of which is the pollution of pharmaceutical wastewater containing antibiotics. In this work, the iron foam-derived electrode (FeOx/if-400) was fabricated by a simple chemical oxidation and heat treatment strategy and served as a green robust cathode for efficient EF degradation of the simulated tinidazole wastewater and real pharmaceutical wastewater. The in situ generated iron oxide nanosheet on iron foam-derived electrode, which contributed to the synergistic catalytic effect of the radical and non-radical pathways in the EF system, and improved the EF activity of the prepared cathode, which resulted in an excellent capacity for wastewater treatment.