Research On The Preparation And Its Degradation To Organic Pollutants In Water Under Lighting With Bi₂WO₆ Hollow Spheres Photocatalyst

The degradation of the organic pollutants in wastewater has been a difficulty in traditional technology of the treatment to wastewater. Recent years, the rising of nanotechnology can well solve the problem.Among nano photocatalyst , the nano Bi₂WO₆ a is widely concerned about for its potential photocatalytic activity.In this thesis, Bi₂WO₆ hollow spheres were successfully prepared by using carbon microspheres as templates under ultrasonic-assisted method. The Bi₂WO₆ hollow spheres photocatalyst were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM). The results showed that the Bi₂WO₆ exhibited hollow spheres structure with extremely good photocatalytic activity to the degradation of dyes wastewater under UV light irradiation or solar light. Through the The investigation of the decolourization efficiency and the TOC removal efficiencies(MB wastewater under UV-light; Rhodamine B under solar light), the Bi₂WO₆ hollow spheres photocatalyst'Significant catalytic performance in visible light was found.1. The preparation of Bi₂WO₆ hollow spheres: using carbon microspheres as templates, controlling the reaction ratio of Bi(NO₃)₃·5H₂O to carbon microspheres and the calcination temperature of the the precursor, the best preparing conditions were found at the weight ratio of 20:1 and the calcination temperature at 500℃. By changing the amount of Bi(NO3)3?5H2O to control the ratio of Bi3+ and the carbon microspheres, the relationship of reactant ratio and the structure of the product was investigated. By changing the calcination temperature of the the brown precursor, the effect of the different temperature to the structure of the product was researched.2. The characterization of Bi₂WO₆ hollow spheres photocatalyst: The crystal structure of as-prepared Bi₂WO₆ hollow spheres was analyzed by X-Ray diffraction (XRD). The morphology and dimensions of Bi₂WO₆ was observed by SEM (JSM-6301, Japan) and The transmission electron microscope (TEM)(JEM-100SX,Japan). The XRD patterns obtained show ed Bi₂WO₆ hollow spheres were in accordance with the russellite structure of Bi₂WO₆,the best Preparation conditions of Bi₂WO₆ hollow spheres is that keep the weight of Bi(NO₃)₃·5H₂O and the carbon microspheres at 20:1 and the calcination temperature of the the precursor is 500℃.3. Photocatalytic activity of Bi₂WO₆ hollow spheres under UV-light: The photocatalytic activity of the as-prepared Bi₂WO₆ hollow spheres was evaluated by the degradation of MB dye wastewater under the UV-light All experiments were carried out in a photo-reaction apparatus as reported in our previous studies. At the reaction time of 80 min, the decolourization efficiency of MB wastewater achieved 78.6% while the TOC removal efficiencies is 64.3%4. Photocatalytic activity of Bi₂WO₆ hollow spheres under solar light: Using Rhodamine B as a contaminant, the photocatalytic activity of Bi₂WO₆ hollow spheres under solar light was performed. The initial reaction mixture was 200 mL of 200 mg/L Rhodamine B solution containing 1 g Bi₂WO₆ hollow spheres. after 144 min irradiation, the decolorization of Rhodamine B was 84.3% and the TOC removal efficiencies 81.9%. The results indicate that The Bi₂WO₆ hollow spheres photocatalyst as-prepared have good photocatalytic activity to dyes wastewater and can use the solar light better which is good for the practical application.