This paper describes the basics of photocatalysis on semiconductors, mainly on TiO2 and the application of photocatalytic processes for water purification from organic and inorganic matter as well as metal removal introduced in order to improve the photocatalytic action of titanium dioxide. The photocatalytic activity of anatase phases of nanocrystalline TiO2 for the degradation of different substances under UV light irradiation. The higher phtocatalytic activity was obtained in anatase phase of TiO2. In the present investigation, result indicates that removal of dye methylene blue(MB) and metal chromium Cr (VI) has been studied by considering influent concentration, loading of photocatalyst, pH and contact time as operating variables. The percentage removal of dye MB and Cr(VI) increase with increase in contact time. The optimum contact time was fixed at 180 minutes for TiO2. The results of this study reveal that the dyes could be removed by semiconducting nanomaterials assisted photoatalytic degradation. The kinetics study of experimental data were analyzed using the pseudo first order kinetics of Lagergren and Pseudo second order model to determine adsorption rate constant. The semiconducting nano materials was charecterised by EDX, XRD and SEM for determining the contents and the size of particles.
