Norfloxacin Degradation by Persulfate Activated with Cu2O@WO(3 )Composites: Efficiency, Stability, Mechanism, and Degradation Pathway

Tungsten trioxide and cuprous oxide composites were successfully prepared by the solvothermal and coprecipitation method. The obtained composites were comprehensively characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), Raman, and PL spectroscopy. The Cu2O@WO3/PS system was developed to degrade norfloxacin (NOR) in an aqueous solution. The photodegradation experiments and electrochemical characterization (EIS and photocurrent curves) showed that Cu2O@WO3(2-1) exhibited optimal photocatalytic activity under visible light. Furthermore, the sulfate radical was corroborated to play a predominant role in the photodegradation process, and the possible free radical formation mechanism was put forward. Density functional theory (DFT) calculation and LC MS were utilized to investigate the intermediates during NOR degradation, and three possible degradation pathways were elucidated. Ecotoxicity analysis by TEST showed that the toxicity of these intermediates was generally weaker than parent NOR. Moreover, the synthetic sample was authenticated to possess good stability and repeatability. This work provided the guidance for available and applicable utilization of persulfate photocatalytic activation technology in pharmaceutical wastewater purification.