Efficient Degradation of Ofloxacin by Magnetic CuFe2O4 Coupled PMS System: Optimization, Degradation Pathways and Toxicity Evaluation.

Abstract

Magnetic CuFe₂O₄ was prepared with the modified sol-gel method and used for enhanced peroxymonosulfate (PMS) activation and ofloxacin (OFL) degradation. The OFL could almost degrade within 30 min at a catalyst dosage of 0.66 g/L, PMS concentration of 0.38 mM, and initial pH of 6.53 without adjustment, using response surface methodology (RSM) with Box-Behnken design (BBD). In the CuFe₂O₄/PMS system, the coexisting substances, including CO₃^2-, NO₃^-, SO₄^2-, Cl^- and humic acid, have little effect on the OFL degradation. The system also performs well in actual water, such as tap water and surface water (Mei Lake), indicating the excellent anti-interference ability of the system. The cyclic transformation between Cu(II)/Cu(I) and Fe(III)/Fe(II) triggers the generation of active radicals including SO₄^•-, •OH, •O₂^- and ¹O₂. The OFL degradation pathway, mainly involving the dehydrogenation, deamination, hydroxylation, decarboxylation and carboxylation processes, was proposed using mass spectroscopy. Moreover, the toxicity assessment indicated that the end intermediates are environmentally friendly. This study is about how the CuFe₂O₄/PMS system performs well in PMS activation for refractory organic matter removal in wastewater.