Degradation of lomefloxacin by MoS2/MIL-53(Fe, Cu) catalyst in heterogeneous electro-Fenton process.

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A novel heterogeneous catalyst named MoS2/MIL-53(Fe, Cu) (MMFC) was prepared by hydrothermal method and applied in a heterogeneous electro-Fenton (hetero-EF) system for lomefloxacin (LOM) degradation in this work. Under the optimal conditions of current density 3mA/cm2, catalyst dosage 0.100g/L, and initial pH 6, 93.5% LOM (2mg/L) removal efficiency was achieved in the MMFC hetero-EF system within 60min, indicating an obvious improvement compared with the MIL-53(Fe, Cu) hetero-EF system. The good catalytic activity was attributed to more effective active sites of the catalyst and the conversion of Fe(II)/Fe(III) and Cu(I)/Cu(II) promoted by Mo(IV) in MoS2, which could be inferred by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) characterizations. The reusability and stability of MMFC were explored based on five cyclic experiments, and the average degradation efficiency reached 73.9%. Furthermore, the hetero-EF system could achieve the total removal of moxifloxacin and tetracycline within 6min and 40min, respectively. Quenching experiments revealed that the hydroxyl radicals (·OH) were the main reactive radicals while superoxide radicals (·O2-) and singlet oxygen (1O2) played a certain part in LOM degradation. Finally, the possible mechanism of the hetero-EF process and LOM degradation pathways were proposed, including substitution, elimination, and cleavage of ring structures. Accounting for good catalytic performance, low preparation cost, and satisfactory versatility, the MMFC exhibited good potential to work as a hetero-EF catalyst for wastewater treatment.