Study Of The Preparation Of Bi₃TiNbO₉ And Its Potocatalytic Property

Photocatalytic oxidation technology is one of important methods used for dye effluent treatment, which has a lot of advantages, such as high efficiency, energy saving, no second contamination and so on. The synthesis and application of photocatalyst is the key of photocatalytic oxidation technology, and the researchers have being searching new photocatalysts with high-activity and low costs.In this work, Bi₃TiNbO₉(BTN) was synthesized by solid-state reaction. The obtained samples were characterized by X-ray diffraction (XRD), scan electron microscopy (SEM), and so on. The single-phase Bi₃TiNbO₉ sample was synthesized successfully at lower temperature (800℃) for 2h .The compound Bi₃TiNbO₉ assumed an Orthorhombic Aurivillius structure with space group Pccn (56) . The La₂O₃-doped Bi₃TiNbO₉ was characterized as well and the doping agent did not change the structure of Bi₃TiNbO₉.The photocatalytic activities of Bi₃TiNbO₉ samples prepared were evaluated by the photodegradation of azo dye 4BS on these catalysts. The effects of some experimental conditions (such as synthetic temperature, catalyst dosage, initial concentration of 4BS solution) on photocatalytic reactions were studied. It can be found that the sample Bi₃TiNbO₉, which was prepared at 800℃ for 2h, showed the highest photocatalystic activity and the degradation rate of 4BS on it was 92.8% after120min under UV irradiation when the initial 4BS concentration was 30 mg/L. The as-prepared samples also showed high photocatalytic activity the photodegradation of acid red G and methyl orange. The La-doping Bi₃TiNbO₉ was studied as well. Experimental results indicated that La-doping could enhances the photocatalytic activity of Bi₃TiNbO₉. But the photocatalytic activity of the catalyst Bi₃TiNbO₉ decreases with icreasing the content of La in it.Finally, the mechanisms on the photocatalytic degradation of 4BS by catalysts were analyzed by infrared analysis (IR) and ultraviolet-visible light analysis (UV-Vis). The degradation of azo dye 4BS on the catalyst Bi₃TiNbO₉ did not owe to the adsorption action, but the photocatalytic oxidation under the UV irradiation. Most of the azo and condensed nucleus structure of 4BS dye could be destroyed by...