Degradation of levofloxacin hydrochloride by Bi2O3/BiFeO3 activated peroxymonosulfate driven by visible light

In this study, Bi2O3/BiFeO3 composites were synthesized by co-precipitation method, which was used to activate peroxymonosulfate (PMS) to degrade levofloxacin hydrochloride (HCl-Lev). The physicochemical properties of Bi2O3/BiFeO3 were regulated by changing the precursor pH, and the structure and morphology were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis). Secondly, the effects of different conditions (precursor pH, pollutant concentration, catalyst dosage, PMS concentration, different anion concentration) on the removal of Lev were investigated. The response surface method (RSM) was used to optimize the experiment parameters and judge the key factors and their interactions. The results showed that the optimal degradation rate of Lev by Bi2O3/BiFeO3/Vis/PMS system was 91.2% ± 1.9% at pH = 7, catalyst dosage 0.5 g/L and PMS concentration 0.4 g/L, which had no significant difference with the predicted value of response surface. After 5 cycles of testing, the degradation rate still reached 83.5% ± 1.0%. Finally, through the radical scavenging experiments, SO4−∙、 ∙OH and h+ were the main active substances. The possible catalytic mechanism of Bi2O3/BiFeO3/Vis/PMS system was proposed.