Photocatalytic deactivation of commercial TiO2 samples during simultaneous photoreduction of Cr(VI) and photooxidation of salicylic acid

TiO2 Degussa P25 and Hombikat UV-100 photocatalysts have been widely characterized. Certain structural and morphological differences have been found. Photocatalytic behaviour has been studied for Cr(VI) reduction and for salicylic acid oxidation, in photoreactions with single and mixed substrates. In the photoreaction with mixed substrates, higher conversion values have been found in comparison to those observed for single substrates. However, clear deactivation process can be noticed. This photocatalytic deactivation is higher for Degussa P25 photocatalyst than for Hombikat UV-100 and can be explained in terms of the surface features exhibited for both TiO2 during the photoprocesses. (C) 2001 Elsevier Science B.V. All rights reserved.