In situ degradation of fluoroquinolone antibiotics in groundwater by CoFe2O4 nanoparticle-activated peroxymonosulfate: Performance, activation mechanism, degradation pathway

For fluoroquinolone antibiotics, which are widely present in groundwater in China and extremely hazardous, highly dispersed CoFe2O4 nanoparticles (NPs) that can efficiently activate peroxymonosulfate (PMS) and rapidly degrade three fluoroquinolone antibiotics, were successfully prepared by the sol-gel method. The presence of Cl− and HCO3− reduced the degradation efficiency of CoFe2O4/PMS system for NOF, while H2PO4− showed a positive effect. The pH range for efficient degradation of fluoroquinolone antibiotics in the CoFe2O4/PMS oxidation system was between 3 and 9. Two reactive radicals, SO4−• and HO•, played an important role in the degradation process. The ability of the catalyst to degrade the antibiotics decreased from the initial 97.12%–88.72% after five repeated uses. The application of density-functional theory (DFT) indicated the chemical bonds in NOF that are vulnerable to free radicals (N13, C5, F19, and O20). Three degradation pathways of NOF were summarized in combination with the LC-MS results. The potential of the CoFe2O4 NPs for practical applications in in situ remediation was verified by testing the migration ability and in situ degradation of NOF in two column experiments. Overall, this paper provides a theoretical basis for the practical application of nanomaterial-activated PMS in ISCO for groundwater remediation.