Efficient degradation of sulfamethoxazole in heterogeneous Electro-Fenton process with CeO2@MoS2@GF modified cathode: Mechanism and degradation pathway

Developing the efficiently degradation of organic pollutants in heterogeneous Electro-Fenton (E-F) process was still a challenge. In this work, the synthesized CeO2 and MoS2 were used to modify graphite felt (GF) for obtaining a novel electrode defined as CeO2@MoS2@GF, constructing a heterogeneous E-F system that could in-situ electrically generate and activate H2O2, thereby efficiently degrading sulfamethoxazole (SMX) in wastewater. The electrochemical performance and catalytic activity of CeO2@MoS2@GF electrode was evaluated by electrochemical tests (LSV/EIS/CV curves and RDE test) and effect of different experimental conditions (SMX concentration, current density and initial pH values). The E-F system using CeO2@MoS2@GF electrode realized rapid SMX degradation of 90% within 20 min and high TOC removal of 87.6% within 120 min, this excellent performance attributed to the efficient conversion between Ce(Ⅳ) and Ce(Ⅲ) under the presence of Mo(IV), as well as the effective utilization of oxygen vacancies. Furthermore, the E-F process mediated by CeO2@MoS2@GF electrode had excellent stability and cycle degradation performance as well as low energy consumption (9.1 kWh kg-1). Besides, this system presented a satisfactory detoxification effect towards degradation intermediates with high toxicity, as well as high adaptability in different water sources. Finally, the mechanism of E-F system using CeO2@MoS2@GF electrode and possible SMX degradation pathways were proposed. This work offered inspiration for developing superior heterogeneous E-F cathode materials and contributed to the practical application of E-F process in wastewater treatment.