Research On Hydrothermal Synthesis, Characterization Of Bi₂O₃-ZnO Composites And Photocatalytic Degradation Of Indigo Carmine

Photocatalytic oxidation technology is a promising, effective, mild operation and energy-saving water treatment technology without any secondary pollution.Considering that ZnO showed unique advantages on photocatalysis, ZnO was selected as research object in this paper. ZnO and Bi2O3-ZnO composites were synthesized by hydrothermal method. The samples were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), UV-Vis diffuse reflectance spectroscopy (DRS), Zeta potential, and Fourier Transform Infrared Spectroscopy. Results showed that hydrothermal synthesized ZnO was of high purity and well crystallized with lead-zinc mine structure, the diameter of 0.25% Bi2O3-ZnO composites was about lOum and the length was about 60um. The ZnO samples were rod-like with a small specific surface area. There was plenty of adsorbed oxygen on the surface of 2.5% Bi2O3-ZnO. All of the synthesized composites samples showed a strong optical absorption in the visible light region. Under acidic conditions, the samples have higher adsorption performance.The photocatalytic activities of the as-prepared Bi2O3-ZnO composites were evaluated by the degradation of indigo carmine under visible light irradiation. Results showed the photocatalytic degradation activities of Bi2O3-ZnO composites were deeply higher than that of ZnO. Furthermore, the photocatalytic degradation activities (88.8%) of 2.5% Bi2O3-ZnO composites were higher than that of N-TiO2. The effects of catalyst loading, initial concentration, pH and the effect of coexisting ions on the photocatalytic degradation efficiency were studied in detail. Moreover, the recycle rate and the performance of 2.5% Bi2O3-ZnO composites were also studied. Results showed that the structure of 2.5% Bi2O3-ZnO composites was stable during the photocatalytic reaction and the photocatalytic activity of the repeated cycles was still excellent. The photocatalytic mechanism of the Bi2O3-ZnO composites was also studied.