Photocatalytic Degradation of Aqueous Rhodamine 6G Using Supported TiO(2) Catalysts. A Model for the Removal of Organic Contaminants From Aqueous Samples

As a model for the removal of complex organic contaminants from industrial water effluents, the heterogeneous photocatalytic degradation of Rhodamin 6G was studied using TiO(2)-derived catalysts, incorporated in water as suspension as well as supported in raschig rings. UV and Visible light were tested for the photo-degradation process. TiO(2) catalysts were synthesized following acid synthesis methodology and compared against commercial TiO(2) catalyst samples (Degussa P25 and Anatase). The bandgap (E(g)) of the TiO(2) catalysts was determined, were values of 2.97 and 2.98 eV were obtained for the material obtained using acid and basic conditions, respectively, and 3.02 eV for Degussa P25 and 3.18 eV for anatase commercial TiO(2) samples. Raschig rings-supported TiO(2) catalysts display a good photocatalytic performance when compared to equivalent amounts of TiO(2) in aqueous suspension, even though a large surface area of TiO(2) material is lost upon support. This is particularly evident by taking into account that the characteristics (XRD, RD, Eg) and observed photodegradative performance of the synthesized catalysts are in good agreement with the commercial TiO(2) samples, and that the RH6G photodegradation differences observed with the light sources considered are minimal in the presence of TiO(2) catalysts. The presence of additives induce changes in the kinetics and efficiency of the TiO(2)-catalyzed photodegradation of Rh6G, particularly when white light is used in the process, pointing toward a complex phenomenon, however the stability of the supported photocatalytic systems is acceptable in the presence of the studied additives. In line with this, the magnitude of the chemical oxygen demand, indicates that, besides the different complex photophysical processes taking place, the endproducts of the considered photocatalytic systems appears to be similar.