Synergistic degradation of levofloxacin (LEV) by Cu2+-activated peroxymonosulfate (PMS) under hydrodynamic cavitation (HC): Efficiency and mechanistic insights.

To effectively eliminate excess antibiotics from aqueous environments and to mitigate the dissemination of antibiotic resistance genes (ARGs), this study proposes a novel degradation system that activates peroxymonosulfate (PMS) through a synergistic combination of hydrodynamic cavitation (HC) and divalent copper ions (Cu2+). Levofloxacin (LEV) is employed as the representative target contaminant to evaluate the system's performance. HC has emerged as a promising technique for pollutant removal. In this study, the localized high-temperature and high-pressure conditions generated by HC not only partially activated PMS but also facilitated its interaction with Cu2+ ions, leading to a pronounced synergistic enhancement in sulfate radical (SO4-) generation and efficient pollutant degradation. Under optimized HC/Cu2+/PMS conditions (Cu2+ = 5 mM, PMS = 2.5 mM, inlet pressure = 0.15 MPa, pH = 10), complete removal of LEV (30 mg/L) was achieved within 50 min. This study elucidates the degradation mechanisms and pathways of LEV within the coupled HC/Cu2+/PMS system and evaluates the ecological safety of its degradation intermediates using the U.S. EPA's T.E.S.T. (Toxicity Estimation Software Tool). Furthermore, the system's applicability was validated through degradation experiments involving a range of representative pollutants, demonstrating its broad-spectrum effectiveness. Crucially, the HC/Cu2+/PMS system demonstrated a superior cavitation yield (2.78 × 10-5 mg/J) and a low electrical energy per order (EE/O) of 229.48 kWh/m3, highlighting its high energy efficiency and practical potential for sustainable wastewater treatment. The experimental results emphasize the system's strong potential for the effective removal of organic pollutants from water, offering a novel and sustainable approach for advanced water treatment.