Synthesis of magnetic MFe2O4@PC (M = Fe, Cu, Co, and Mn) composites and application of heterogeneous photo-Fenton efficient removal of metronidazole under visible light

Nanoscale magnetic spinel ferrite composites with the general formula MFe2O4@PC (M = Fe, Cu, Co, and Mn; PC = biochar) were prepared by a facile impregnation and pretreatment method. MFe2O4@PC particles were deliberated by X-ray Diffractometer (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM), Brunauer-Emmett-Teller adsorption-desorption isotherm (BET), X-ray Photoelectron Spectroscopy (XPS) and Vibrating Sample Magnetometer. The results showed that MFe2O4 coating, which is evenly distributed on the surface of HNO3- pretreated biochar, can provide more active sites to enable MFe2O4@PC to be activated by visible light. The XRD confirmed that the crystallite sizes of MFe2O4 ranged from 10.0 to 27.9 nm. With the help of surface-OH, PCoF has a rapid adsorption performance on metron-idazole (MNZ) and can degrade 99% of MNZ within 20 minutes at an optimal pH of 3.0. Meanwhile, the PCuF composites showed excellent photo-Fenton catalytic performance for the degradation of MNZ under neutral pH conditions, and 96.0% of MNZ (300 mg/L) could be removed within 120 min. This study confirmed (OH)-O-center dot is the main reactant, while O-2(center dot) and h(+) contributed to the degradation of MNZ during photocatalysis. MFe2O4@PC composite can be separated easily by an external magnetic field. The synthesized PCoF was reused for 5 cycles and it was clear that it had no significant loss, indicating its excellent ability to remove MNZ from wastewater. (c) 2023 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.