Acceleration of levofloxacin degradation by combination of multiple free radicals via MoS2 anchored in manganese ferrite doped perovskite activated PMS under visible light

The nanocomposite of MoS2 embedded manganese ferrite doped perovskite (SrCoO3/MnFe2O4/MoS2, abbreviated as SMM) was successfully synthesized for peroxymonosulfate (PMS) activation under visible-light. It was optimized that the SMM-3 (mass ratio of MoS2 modified nanocomposite was 0.3) exhibited excellent catalytic performance to activate PMS for levofloxacin (LVF) degradation, with the degradation efficiency of 95.1% in 20 min. Besides, SMM-3 was able to efficiently degrade LVF under real water matrix. The quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that SO4•- and HO• played a dominant role in reaction. Due to the photocatalytic property of nanocomposites, the visible light could excite electrons to react with oxygen and form O2•-, which further reacted with HO• to produce 1O2. In the reaction process, the rapid redox cycle of metal ions (including Co, Mn, Fe and Mo) boosted the activation of PMS and promoted the degradation of LVF in a short time. The Density functional theory (DFT) calculation and LC-MS/MS further revealed that oxidation of piperazine ring, decarboxylation and defluorination processes were the main LVF degradation pathways. Finally, the toxicity analysis based on Toxicity Estimation Software Tool (T.E.S.T) verified the ecological risks of transformation residues.