Synthesis and Photocatalytic Capability of Cr-TiO2 Film

A TiO₂ catalyst doped by Cr was prepared by the sol-gel method and characterized by UV-2550 and FS. The results revealed that the Cr⁶⁺-doped TiO₂ film had the higher photocatalytic activity than pure TiO₂ film. Introduction Semiconductor photocatalysts, mainly TiO₂, have attracted much attention in last decade because of their potential application in the removal of many organic and inorganic pollutants in air or water. Many studies have been carried out on the application and modification of TiO₂, and various photocatalytic reactors have been investigated according to respective application demands for the purification of air and water. In the water and wastewater treatment field, slurry reactor is the most common device because of its high specific surface area and good dispersion. However, the use of TiO₂ slurry reactor is still limited mainly due to difficult separation of TiO₂ particles from treated water. To overcome the problem, Titania beads, TiO₂ based thin film, fiberglass loaded with titania, and encapsulated titania within a zeolite framework have been prepared and used in fixed bed. However, the activity of TiO₂ photocatalyst is reduced to a considerable extent by these immobilization techniques because the effective surface area of photocatalysts is decreased considerably. The aim of this study is to obtain a magnetically separable photocatalyst, which is stable and easy to be prepared. In the work, Cr as magnetic cores was prepared by liquid catalytic phase transfer method at low temperature, and magnetically separable TiO₂-Cr photocatalysts were synthesized. Their physicochemical properties and photocatalytic activity for degradation of methyl orange in water were investigated.