Preparation Of Bismuth Tungstate Based Composite Photocatalyst And Study On Its Photocatalytic Degradation Of Rhodamine B

Photocatalytic oxidation technology is one of the most potential technologies in the treatment of printing and dyeing wastewater because of its mild reaction conditions and simple operation.Bismuth tungstate（Bi₂WO₆）has a unique layered structure and a good light response range,which can effectively degrade printing and dyeing wastewater.However,its application is restricted by the factors of low quantum yield,low light energy utilization rate and high photo-generated carrier recombination rate.In this paper,r GO/Bi₂WO₆ was prepared by hydrothermal method,and Ag/r GO/Bi₂WO₆composite photocatalytic material was prepared by the method of photoreduction supported Ag to improve the availability of visible light and the photocatalytic performance of Bi₂WO₆.The phase composition,surface characteristics and light absorption properties of the composite catalyst samples were characterized by XRD,SEM,FT-IR,XPS,N₂ physical adsorption desorption,UV-Vis diffuse reflectance spectroscopy and PL,and the photocatalytic performance of the composite catalyst was investigated using rhodamine B（RhB）as simulated wastewater.The main research contents and results are as follows:1.GO was synthesized by Hummers’method,and then r GO/Bi₂WO₆ composite photocatalyst was prepared by hydrothermal method and Bi₂WO₆ composite.The effects of preparation conditions on the r GO/Bi₂WO₆ composite catalyst were investigated by adjusting the complex mass ratio of r GO and Bi₂WO₆,hydrothermal time and p H of precursor solution.The results show that when the composite mass ratio is1.5%r GO/Bi₂WO₆,the hydrothermal time is 24 h,and the precursor p H is 1.42,the composite catalyst sample has the best light absorption performance,and the degradation efficiency of RhB can reach 91.73%.2.The Ag/rGO/Bi₂WO₆composite photocatalyst was prepared by photochemical reduction method with Ag loading.The effects of Ag loading and photoreduction time on the performance of the composite photocatalyst were investigated.The results show that when the composite mass ratio is 15%Ag/1.5%r GO/Bi₂WO₆ and the photoreduction time is 4 h,the degradation efficiency of RhB can reach 96.97%.3.15%Ag/1.5%r GO/Bi₂WO₆ composite photocatalyst was prepared under the optimal preparation conditions,and the effects of RhB process parameters on the degradation performance of the catalyst were investigated.The results show that when the initial concentration of RhB is 50 mg/L,the p H of the original RhB solution remains unchanged,and the dosage of catalyst is 0.1 g/100 m L,the degradation efficiency of RhB can reach the highest.4.Kinetics of photocatalytic degradation of RhB simulated wastewater by Bi₂WO₆,1.5%r GO/Bi₂WO₆ and 15%Ag/1.5%r GO/Bi₂WO₆ samples were studied.The capture experiment of active group showed that the hole（h⁺）was the main active molecule in the reaction,and illustrated the possible photocatalytic degradation mechanism.