Efficient visible-light photocatalytic degradation of sulfadiazine sodium with hierarchical Bi7O9I3 under solar irradiation

Bi 7 O 9 I 3 , a kind of visible-light-responsive photocatalyst, with hierarchical micro/nano-architecture was successfully synthesized by oil-bath heating method, with ethylene glycol as solvent, and applied to degrade sulfonamide antibiotics. The as-prepared product was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflection spectra and scanning electron microscopy (SEM). XRD and XPS tests confirmed that the product was indeed Bi 7 O 9 I 3 . The result of SEM observation shows that the as-synthesized Bi 7 O 9 I 3 consists of a large number of micro-sheets with parallel rectangle structure. The optical test exhibited strong photoabsorption in visible light irradiation, with 617 nm of absorption edges. Moreover, the difference in the photocatalytic efficiency of as-prepared Bi 7 O 9 I 3 at different seasons of a whole year was investigated in this study. The chemical oxygen demand removal efficiency and concentration of NO 3 − and SO 4 2– of solution after reaction were also researched to confirm whether degradation of the pollutant was complete; the results indicated a high mineralization capacity of Bi 7 O 9 I 3 . The as-synthesized Bi 7 O 9 I 3 exhibits an excellent oxidizing capacity of sulfadiazine sodium and favorable stability during the photocatalytic reaction.