Preparation And Photocatalytic Property Of Opal Supported Nano-TiO₂

Opal is a kind of rare mineral, currently found in Heilongjiang province and Xinjiangprovince, which has a character of high porosity, strong adsorption, good resistance to heat.There will provide a new way to utilize opal using it as a support of nano-TiO₂.In this paper, dilute acid solution was used to activate opal, then with Ti(OBu)4aspresursor, the activated opal as support, a series of different calcination temperature,different TiO₂loading on opal photocatalysts were synthesized by using a facile sol-gelmethod. The activation experiments showed the pretreated sample is more suitable forloading TiO₂. The as-obtained photocatalysts were characterized with Fourier transforminfrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET),Transmission electron microscope (TEM), Scanning electron microscope (SEM) materialanalysis instruments. FT-IR graph indicte that the vibration of Ti-O-Ti appeared in thephotocatalysts. The XRD spectrum show the calcination temperature has an importantinfluence on the crystal transform and the grain size of nano-TiO₂. The TEM images showthe nano-TiO₂are loaded on the surface of opal uniformly. The BET show the specificsurface area and pore volume significantly decreased due to the loading of nano-TiO₂.The methylene blue solution and xenon lamp were used as a pollutant model and theUV light source respectively, the removal effect for the methylene blue of thephotocatalysts were investigated. Calcination temperature, TiO₂loading, oxidant dosage,pH and other factors on the photocatalytic activity were mainly studied in this paper, thebest ratio of every factor to the photocatalytic activity were given in the end. The studyshowed that the prepared photocatalysts have the advantage of the strong adsorption andthe high photocatalytic activity, and have the good property to the removal of themethylene blue.