The synergistic mechanism of an FeS2/ACFs self-standing membrane in highly efficient electro-Fenton anitibiotic degradation: carbon nanodefects and free radical analysis

Abstract

Antibiotics are challenging to degrade in wastewater using conventional methods. Advanced oxidation processes (AOPs), such as electro-Fenton treatment, have garnered attention for their high efficiency, non-toxicity, and complete degradation of antibiotics, further enhanced by the incorporation of nanotechnology. In this study, Fe-MOF derived pyrite (FeS₂) nanoparticles were successfully loaded onto aligned carbon nanofibrous (ACFs) membranes (FeS₂/ACFs). The FeS₂/ACFs membranes were used as highly efficient electrocatalytic self-standing membranes for the electro-Fenton treatment of antibiotic wastewater, using tetracycline (TC) as a model pollutant. The FeS₂/ACFs membranes were designed to increase free radicals and carbon nanodefects, which enhanced the synergistic effects of electrocatalysis and adsorption. A single-pass degradation rate of 100% was achieved for 100 mg l⁻¹ of TC utilizing a flow-through membrane reactor. The results highlight the effectiveness of the FeS₂/ACFs membranes for the complete removal of pollutants under mild operating conditions. The atomic level synergistic mechanism was analyzed including carbon nanodefects and free radicals using DFT, EPR and the quenching method. The major intermediates and potential degradation pathways were elucidated by LCMS/MS and DFT LUMO–HOMO calculations. This mechanistic analysis provided insights into the complex transformation processes occurring during antibiotic degradation.