Due to biodiversity and reduced rainfall, water pollution is a major concern of the world’s population and so access to reliable water resources is a central issue in most countries. Thus there are many challenges today in the treatment of drinking water and industrial wastewater. Using sun power and photocatalytic methods are environmentally way to water treatment. Titanium oxide is the most important photocatalyst due to its properties and excellent stability in different environments. But because its band gap is relatively high, this material is only active in the UV region. Therefore doping of some compounds can be used to make it more active. In this study single phase, two phase and three phase doped TiO 2 by Copper, Nickel and Zinc were prepared by sol gel method. Phase, morphology, structure and band gap evaluation of prepared samples were studied by GIXRD, SEM, EDX and UV-Visible DRS analysis. Presence of TiO 2 with Anatase phase as well as presence of Cu, Ni and Zn elements in the coatings and reduction of band gap were confirmed by these analysis. Also the optical properties of the photocatalytic activity of coatings were evaluated by LSV, CA, OCP and MB degradation analysis. The results showed that the modified coatings with Cu, Ni and Zn showed better photocatalytic activity than pure TiO 2 coating. Water treatment tests were carried out to investigate the effect of photocatalytic coatings on industrial wastewater which results indicated that doped coatings with high production of radical hydroxyls as a strong oxidant to reduce organic containments and microorganisms performed much better than un doped TiO 2 coating. Tafel polarization and impedance tests were performed in dark and UV light conditions to evaluate the corrosion resistance of coatings. In dark condition the coatings showed better behavior due to the formation of oxide layers. So that the three phase doped TiO 2 film showed the best corrosion resistance. In addition under UV illumination due to the light absorption and more crossing current, corrosion resistance has decreased.
