Preparation Of Bismuth-Based Binary Heterojunction Photocatalysts And Their Performance For Reduction Of U(?)

In view of the current pollution of radioactive waste water,it is very important to find a safe,reasonable and effective method for treating uranium-containing waste water.In recent years,methods for treating uranium-containing waste water by photocatalytic technology have gotten extensive attention.Bismuth-based semiconductor materials is a promising material due to its unique electronic structure,excellent visible light adsorption capacity,narrow band gap and high photocatalytic activity.Moreover,at this stage,the research on bismuth catalysts is still in its infancy.Therefore,it is increasingly valuable to design some efficient,environmental friendly lanthanide photocatalytic materials to treat environmental pollution.Two kinds of visible light-responsive heterojunction photocatalysts CuO/BiFeO₃ and Cu₂O/BiVO₄ were prepared by wet impregnation method.Through Scanning electron microscopy?SEM?,X-ray diffractometry?XRD?,X-ray energy spectrum?EDS?,X-ray photoelectron spectroscopy?XPS?,UV-visible diffuse reflectance?UV-Vis?and specific surface area determination?BET?method to characterize and analyze the catalyst materials.They were used to remove U???in aqueous solution for photocatalytic reduction experiments and study the photocatalytic effects under different conditions.The article specifically analysis is from the following points:?1?The BiFeO₃ material was synthesized by sol-gel method,and then the visible lightresponsive semiconductor heterojunction CuO/BiFeO₃ photocatalyst was synthesized by loading the different mass ratios of CuO onto the surface of BiFeO₃ by wet impregnation.The surface morphology,crystal structure,nuclide content and optical properties of the material were analyzed by various methods and investigated the removal effect of U???on CuO/BiFeO₃ photocatalyst under visible light,and the recycled materials were subjected to recycling experiments.The results show that the CuO/BiFeO₃ photocatalyst with 10% CuO ratio under the condition of pH = 4.5,the sample dosage is 0.6 g/L,the initial concentration of U???is 5 mg/L,and the amount of hole trapping agent is 8% has the fastest catalytic reduction rate,and the removal rate reached 95% when the reaction time was 120 min.The reaction process conforms to the first-order kinetics law and it has good recycling performance.?2?The BiVO₄ material was synthesized by citric acid complex method,and then the visible light-responsive semiconductor heterojunction Cu₂O/BiVO₄ photocatalyst was prepared by loading different molar ratios of Cu2 O onto the surface of BiVO₄ through wet impregnation.The material was characterized by various methods to analyze the properties and studied the effects of different conditions on the removal of U???by Cu₂O/BiVO₄ photocatalyst under visible light.The results indicate the Cu₂O/BiVO₄ photocatalyst with 2% Cu2 O molar ratio under the condition of pH = 5.5,the sample dosage is 0.8g/L,the initial concentration of U???is 5 mg/L,and the amount of hole trapping agent is 8% has the fastest catalytic reduction rate,and the removal rate reached 99% when the reaction time was 100 min.The reaction is consistent with the law of first-order kinetics law.?3?By comparing the characterization of elemental and the reduction efficiency of U???in solution of the semiconductor catalysts and heterojunction semiconductor catalysts,the results show that the heterojunction catalyst has better visible light absorption performance and narrower band gap than the elemental semiconductor catalyst,meanwhile,its removal efficiency is much higher than the elemental catalyst.