Investigation of Structure, Performance and Application of Photoreactors Based on Titanium Dioxide

Photocatalyst is made of combination of two words; photo as the light and catalyst. Among the materials with photocatalytic properties, titanium dioxide (TiO2) is more interested due to wide band gap, non-toxic properties, light and chemical stability, easy to access and relatively low cost. In recent years, the use of TiO2 for water treatment, air purification and hydrogen generation has been widely reported, either as a powder in slurry systems or immobilized to various supports. Beyond that, the by-products during these processes appear to be non- toxic. Chemical vapor deposition, Physical vapor deposition, Sol-gel and Hydrothermal processes are some examples of methods employed to obtain TiO2 films supported in inert surfaces. One of advantage on the application of immobilized catalyst is the fact that it can be re-used for several treatment cycles while keeping its stability. Photoreactors depends on application of photocatalyst, have several categories such as: Slurry, Fluidized bed, Fixed bed, Optical fibers and Photoelectrochemical reactors. Among these categories, generally the slurry reactors have the highest efficiency but imply a post-filteration step to retain the photocatalyst. Monolithic fixed bed reactors in comparison with other reactors show better performance in all aspects. Therefore, the purpose of this article is to study structure and performance of listed photoreactors and present the results of some new researches.