Photocatalysis; principles and some applications

It has been proven that the presence of catalysts enhances the rate of reactions. Also, the role of TiO2 as a photocatalyst in oxidation and photodecomposition has been studied. On the other hand, the discharge of the colored compounds in the environment causes considerable non-aesthetic pollution and serious health-risk factors. Since conventional wastewater treatment plants cannot degrade the majority of these pollutants, powerful methods for the decontamination of dyes wastewaters have received increasing attention over the past decade. In this work, the contents have been presented about the principles of photocatalysis process. In this regard, band theory has been mentioned that it is indicative of the main cause of the difference between conductive, semiconductor and insulator materials. In the following, the phenomena occurring due to the optical excitation effect of a semiconductor have been discussed. Also, the structure of some allotropes of TiO2 has been investigated. In the end, briefly, some applications of photocatalysis process, particularly in the removals of pollutants from wastewater have been expressed.