Photocatalytic Oxidation of Pollutant Dyes in Wastewater by TiO2 and ZnO nano-materials – A Mini-review

In recent years, photocatalytico oxidation processes with ultra violet (UV) radiation and semiconductor photocatalyst like titanium dioxide (TiO2) and zinc oxide (ZnO) have gained immense research interest as an effective wastewater purification method because of its efficacy in decomposing and mineralising the hazardous organic pollutants as well as the opportunity of utilizing the solar UV and visible spectrum. A comprehensive review of the UV assisted heterogeneous photocatalytic oxidation process is conducted with a border perspective into the photocatalytic reaction mechanism involved, different form of TiO2 and ZnO catalysts, effective application towards waste water treatment by immobilized on surface or as suspension. Photocatalytic decomposition with ZnO and TiO2 catalysts is mainly applied for treating organic contaminants dyes in wastewater because of their ability to attain fully mineralization of the organic contaminants under mild reaction conditions such as ambient pressure and temperature. One hundred and eighty seven published papers are reviewed and summarized here with the center of attention being on the photocatalytic oxidation of organic dyes present in waste water effluent. Most recently, photocatalytic degradation of oraganic molecules using TiO2 and ZnO have been studied extensively due to the degradation of persistent organic pollutants, PAH (Polycyclic Aromatic Hydrocarbons) dyes and other organic chemicals which are known to be endocrine disruptors. Treatment of wastewater in a titanium and zinc dioxide suspended reactor has been widely used due to its simplicity and enhanced photodegradation efficiency.