Preparation, Characterization And Photocatalytic Properties Of Bismuth Tungstate Composite Photocatalysts

In recent years more and more people pay attention to water pollution problems and to seek an effective environmental governance approach has become the common goal of scholars. Photocatalytic technology of causing social broad attention has the advantages of cleaning, convenience and mildness. Among them, as one of the visible light response photocatalysts, Bi2WO6 has special phase structure, good physical and chemical properties. In terms of using visible light and photocatalytic degradation of pollutants, Bi2WO6 has shown a good prospect for the application. In this study, Bi2WO6 was modified to prepare composite photocatalysts. The photocatalytic performance of composite photocatalysts was evaluated through exploring degradation ability of ciprofloxacin.Bi2WO6 nano-material and Co0.5Zn0.5Fe2O4 magnetic matrix were prepared respectively through hydrothermal method and sol-gel method, and Co0.5Zn0.5Fe2O4/Bi2WO6 composite magnetic photocatalysts of different mass ratio were synthesized under the action of ultrasound. The crystal phase structure, morphologic structure and specific surface area of Co0.5Zn0.5Fe2O4/Bi2WO6 composite magnetic photocatalysts were analysed, the results shown that the main phase of Co0.5Zn0.5Fe2O4/Bi2WO6 composite magnetic photocatalyst was Bi2WO6, and its crystallinity increased. The study of photocatalytic degradation of ciprofloxacin showed that when the composite mass ratio was 1:8, photocatalyst dosage was 75 mg, solution concentration of ciprofloxacin was 10 mg · L-1, pH was 7, the degradation rate of ciprofloxacin of Co0.5Zn0.5Fe2O4/Bi2WO6 composite magnetic photocatalyst reached maximum which was 92.24% after photocatalytic reaction for 120 min under 500 W xenon lamp.The kaolin/Bi2WO6 composite photocatalysts of different mass ratio were synthesized using hydrothermal method. The crystal phase structure, morphologic structure and specific surface area of kaolin/Bi2WO6 composite photocatalysts were analysed, the results showed that kaolin/Bi2WO6 composite photocatalysts were self-assembly using nanosheets as a flower. The particle size of photocatalysts increased for adding kaolin. The photocatalytic properties of kaolin/Bi2WO6 composite photocatalysts were evaluated using ciprofloxacin as target contaminant, the results showed that when the mass ratio was 8wt%, the degradation effect of ciprofloxacin was the highest. In the process of photocatalytic reaction, photocatalyst dosage, initial concentration of ciprofloxacin and pH had influence on the degradation of ciprofloxacin. The degradation rate of ciprofloxacin of 8wt% kaolin/Bi2WO6 composite photocatalyst reached maximum which was 97.7% after photocatalytic reaction for 120 min under 500 W xenon lamp, under the-condition: photocatalyst dosage 50mg, solution concentration of ciprofloxacin 5 mg L-1 and pH 7. The comprehensive effects of photocatalyst degradation of ciprofloxacin of 8wt% kaolin/Bi2WO6 composite photocatalysts using the response surface method were studied, and obtained the optimal values of the various reaction conditions:photocatalyst dosage 60 mg, solution concentration of ciprofloxacin 6.5 mg · L-1 and pH 7.19.