The dual pathway mechanisms of peroxyacetic acid activation by CoMn2O4 spinel for efficient levofloxacin degradation

In this work, CoMn2O4 spinel catalyst was used for the first time to activate peroxyacetic acid (PAA) for the degradation of fluoroquinolone antibiotic levofloxacin (LVF). The results showed that the degradation efficiency of CoMn2O4/PAA system reached 93% within 15 min at initial LVF concentration of 20 mg/L. In addition, the bimetallic oxide CoMn2O4 with spinel structure showed significantly higher activation performance than the single metal oxide (Co3O4 and MnO2). The excellent PAA activation performance by CoMn2O4 was attributed to the redox cycles between Co3+/Co2+, Mn3+/Mn2+, and Mn4+/Mn3+, as well as the synergistic interaction between Co and Mn species. Radical quenching and electron paramagnetic resonance (EPR) spectra results indicated that acetylperoxyl radical (CH3C(O)OO·) was the dominant radical species, and this work highlighted that 1O2 played an important role in non-radical process in PAA-based AOPs for the first time. The production of 1O2 may be attributed to the interaction between reactive oxygen (O*) and PAA. In addition, the CoMn2O4/PAA system has been proved to have great stability and reusability, and exhibit selective degradation of organic pollutants which contained electron-rich groups. Overall, this work presents perspective for the application of antibiotic remediation by CoMn2O4/PAA process.