The Preparation Of Doped TiO₂ Photocatalyst And Its Application In Treatment Of Dye Wastewater

Titanium dioxide is one of important semiconductor materials. It has always regarded as the most promising photocatalyst, dut to its several advantages, such as chemical stability, photo corrosion resistance, non-toxicity, low cost and so on. But it is a wide bandgap semiconductor (Eg=3.2eV), so it can only absorb UV and has a low utilization efficiency of solar energy. At the same time, its photo-induced carriers have a high recombination rate. These disadvantages of titanium dioxide limit its photocatalytic oxidation in practical applications. How to improve the photocatalytic activity of titanium dioxide is the key to apply the TiO2 photocatalyst.The main way is modification. That is by changing the particle structure and surface properties, expand the range of photoresponse, inhibit of photo-carrier recombination and increase the quantum efficiency to improve the stability and photocatalytic activity of photocatalytic material. Conventional methods are ion doping, noble metal deposition, coupling with narrow-bandgap, dye-sensitization,and so on. The most commonly used methord is doping. Due to its relatively low cost, easy control of material composition, and so on.Therefore doping is an important method for TiO2 to get visible light response activity.Three main areas of work were carried out in this thesis.1. Preparation, Characterization and Photocatalytic Activity of Boron-doped TiO2With the P123 as a template, tetraethyl titanate as the source of titanium, boric acid as the boron source, boron-doped TiO2 was synthesized at a certain temperature and humidity with evaporation induced self-assembly method. And then after drying and calxination, we get it. Its photocatalytic activity was tested through using methylene blue as the target pollutant. The results showed that the catalyst had a higher photocatalytic activity under visible light irradiattion. We also discussed the effect of the solvent, inhibitor (inhibiting the hydrolysis of tetraethyl titanate) and catalyst calcination temperature on the activity of the catalyst in the process of catalyst preparation.2. Preparation, Characterization and Photocatalytic activity of Co-doped mesoporous TiO2With P123 as a template, through evaporation induced self-assembly method, we prepared several groups of co-doped mesoporous TiO2 photocatalyst, including B-N, B-S, B-Ag, B-Ti3+, B-Co and B-Ce. The obtained photocatalysts were characterized by TEM, XRD, adsorption-desorption isotherm and UV-vis spectroscopy. Finally, the photocatalytic activity was tested through using methylene blue as the target pollutant. The results showed that all catalysts have a strong absorption under visible light. B-N co-doped mesoporous TiO2 photocatalyst shows the best among these codoped photocatalysts.3. Preparation, Characterization and Photocatalytic activity of doped TiO2 photocatalystWith mesoporous molecular sieve SBA-15 as a support, we successfully load of the titanium dioxide to the outer surface and pore surface of SBA-15 by impregnation method, then doped two non-metallic elements B and N into TiO2 We obtained co-doped mesoporous titanium dioxide with a high specific surface area was obtained. The photocatalytic activity was tested through using indigo carmine as the target pollutants. Experimental results show of that with this method, the obtained catalyst has a higher photocatalytic activity under visible light irradition.