Synthesis, characterization and visible‐light‐induced photocatalytic activity of powdered semiconductor oxides of bismuth and zinc toward degradation of Alizarin Red S,

Abstract

Semiconductor oxides of bismuth and zinc have been synthesized using modified sol-gel method and sol-combustion method, respectively. The synthesized catalysts were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy. The photocatalytic activity of Bi2 O3 and ZnO was evaluated for the degradation of Alizarin Red S (ARS), as a model pollutant, at 20 mg/L level in water under visible light irradiation. The percentage of photocatalytic degradation was determined using UV-vis spectrophotometer. The photocatalytic results revealed that Bi2 O3 and ZnO could effectively degrade 73% and 53% of ARS, respectively, within 13 hr under visible light illumination, indicating that synthesized Bi2 O3 is a better photocatalyst than ZnO. Photodegradation of ARS with Bi2 O3 and ZnO is remarkably influenced by change in pH of the dye solution, and pH 8 was found to be the most favorable for maximum removal of ARS in case of both Bi2 O3 (75%) and ZnO (58%) photocatalyst. PRACTITIONER POINTS: Photocatalytic degradation of ARS dye depends on pH of the solution. Calcination temperature influences the crystallite size of prepared semiconductor oxides of bismuth and zinc. Bi2 O3 shows better photocatalytic degradation efficiency than ZnO under visible light illumination.