Study of photocatalytic oxidation of indigo carmine dye on Mn-supported TiO2

A detailed comparative investigation on the discoloration (adsorption) and mineralization (in the presence of UV irradiation) of indigo carmine (IC) dye over four photocatalysts TiO2-D (from Degussa), TiO2-SG (prepared with a sol-gel method), Mn/TiO2-imp (prepared with an impregnation method) and Mn/TiO2-SG (prepared with a sol-gel method) is presented. The experimental results show that Mn/TiO2-imp gives the highest photocatalytic activity. Whoever, the influence of pH, catalyst amount and time on the decolorization rate of IC on Mn/TiO2-imp was thoroughly discussed and correlated with ZPC of MnOx species, various exposed species of MnOx and surface properties. XRD, Fr-IR and N-2 adsorption measurements were used as characterization techniques over the calcined catalysts at 550 degrees C. Electric conductivity measurements by applying zeta potential technique provide an insight into the electric static situation of the particles at a given pH. (c) 2007 Elsevier B.V. All rights reserved.