Preparation Of H₃PW₁₂O₄₀-TiO₂/SiO₂ And Study On Degradation Of Rhodamine B Solution

The efficient treatment of wastewater from dyestuff industry has important practical applications. Because of the simpleness and low energy consumption, the techinic of degrading wastewater from dyestuff industry by photocatalytic way has become the hotspot. The key of this is how to prepare efficient photocatalyst.In this paper, H₃PW₁₂O₄₀-TiO₂/SiO₂ catalysts are prepared by impregnation method, with the silica gel acting as the supporter of the catalysts. The structure of the catalysts was also determined by IR,TG-DTA,XRD and XPS. TiO₂ in the catalysts exist as the type of anatase and the phosphotungstic acid still keep the elementary framework of the Keggin structure. In addition, the bonding action exists between TiO₂ and the phosphotungstic acid.The photocatalytic activity of catalyst and the effect of some factors such as composite, dosage and the repeated times of catalyst, intensity of light, temperature and degradation environment on degradation ratio are investigated in the paper. Comparison of catalytic activities was also drawn between H₃PW₁₂O₄₀-TiO₂/SiO₂ and TiO₂/SiO₂ under the same conditions.The results show that the high degradation ratio is obtained in ultrasonic/ ultraviolet radiation/catalyst circumstances, and the optimal composition of catalyst is 4g H₃PW₁₂O₄₀ on 11g SiO₂. The best intensity of light is 15 cm and the optimal dosage of the catalyst is 0.2 g. And it is also found that there is little influence of temperature on the degradation of rhodamine B, as there was just a little increase of degradation radio with time bying. What's more, the catalyst is repeated for 6 times after simple treatment, but the degradation radio still gets to 95.65%. Compared with TiO₂ alone, H₃PW₁₂O₄₀-TiO₂ can obviously improve the ultrasonic and photocatalytic degradation ratio of rhodamine B. Because H₃PW₁₂O₄₀, which is a more active electron supporter, effectively complete the electron transfer from TiO₂ catalyst surface to O₂ molecule, so a part of electron cavity compound is restrained, and then the concentration of·OH in the solution increases. As a consequence, the degradation ratio of rhodamine B is effectively improved.