Peroxyacetic acid (PAA)-based advanced oxidation processes (AOPs) have attracted much attention in wastewater treatment by reason of high selectivity, long half-life reactive oxygen species (ROS), and wider applicability. In this study, cobalt ferrite (CoFe₂O₄) was applied to activate PAA for the removal of ofloxacin (OFX). The degradation of OFX could reach 83.0% via the CoFe₂O₄/PAA system under neutral conditions. The low concentration of co-existing anions and organic matter displayed negligible influence on OFX removal. The contributions of hydroxyl radicals (·OH), organic radicals (R-O·), and other reactive species to OFX degradation in CoFe₂O₄/PAA were systematically evaluated. Organic radicals (especially CH₃C(O)OO·) and singlet oxygen (¹O₂) were verified to be the main reactive species leading to OFX destruction. The Co(II)/Co(III) redox cycle occurring on the surface of CoFe₂O₄ played a significant role in PAA activation. The catalytic performance of CoFe₂O₄ remained above 80% after five cycles. Furthermore, the ecotoxicity of OFX was reduced after treatment with the CoFe₂O₄/PAA system. This study will facilitate further research and development of the CoFe₂O₄/PAA system as a new strategy for wastewater treatment.

The residual emerging pollutants in secondary effluent from a chemical industry park contain potential risks for natural waters. Herein, the cobalt ferrite/peracetic acid system was employed to destroy aniline, a typical emerging pollutant, with a reaction rate of 0.0147 min⁻¹ at pH 7.0. Singlet oxygen (¹O₂) served as the predominant reactive species for aniline degradation, with superoxide radicals (O₂⁻) and organic radicals (R-O) acting in secondary roles. The valence transition between Co(II) and Co(III) on the CoFe₂O₄ surface played a determining role in the reaction progression. The presence of anions and humic acids with low concentrations had minimal impact on aniline removal. Additionally, the CoFe₂O₄ catalyst demonstrated excellent recyclability, maintaining a pollutant removal rate above 93% over five consecutive cycles. Lastly, the CoFe₂O₄/PAA system demonstrates effective treatment of typical pollutants, including phenolic compounds, pesticides, antibiotics, and dyes, achieving removal rates of 77.48% to 99.99%. Furthermore, it significantly enhances water quality in the treatment of actual secondary effluent, offering a novel theoretical foundation and practical insights for applying this catalytic system in wastewater treatment.