Resveratrol-mediated Fe(III)/peroxydisulfate activation for ofloxacin degradation at circumneutral pH

Iron-mediated peroxydisulfate (PDS) activation is limited by slow Fe(III)/Fe(II) redox cycling under circumneutral conditions. Here, resveratrol (RES), a natural stilbene polyphenol, was introduced as a low-dose redox mediator to promote Fe(II) formation from Fe(III) for enhanced PDS activation. The Fe(III)/RES/PDS system showed higher ofloxacin (OFL) degradation than the corresponding single-reagent and binary systems and achieved approximately 90% OFL degradation at pH 6.5. Chemical quenching and competition-kinetic analysis indicated that sulfate radical (SO₄ ^·-) was the major contributor to OFL degradation, while hydroxyl radical (^·OH) played a secondary role. Matrix experiments showed that Cl^- and NO₃ ^- had minor effects, whereas NO₂ ^- strongly inhibited OFL degradation. This work provides a case study of RES-mediated Fe(III)/PDS activation for antibiotic degradation under near-neutral conditions.