Water pollution has a major impact on the natural ecological balance and is also considered a threat to human health. Synthetic paints are used extensively in various fields such as ceramics, plastics, textiles, paper, printing, cosmetics, medicine and leather due to their low cost. Textile wastes containing carcinogenic dyes, toxic heavy metals, phenolic compounds and other chemicals are dangerous ecological factors that cause water pollution. Every year, one of these pollutants discharges about 100 tons of dyestuff from factories to water resources or the environment. Therefore, the removal of dyes from waste water is necessary for aquatic life and humanity. Many different strategies have been developed for the solution. Coagulation, flocculation, membrane filtration, adsorption and especially photocatalysis are methods used for water pollution problems. Semiconductor photocatalysis as a "green" technology is one of the most effective ways to solve this kind of pollution problem. For wastewater treatment, the improvement of efficient performance and low cost visible light powered photocatalysts are gaining much attention.
