On the enhanced catalytic activity of TiO2-supported layered compounds forCr(VI) photo-reduction

TiO2 supported layered compounds (SLCs) with different loading amounts of l ayered compound (LC) were prepared via impregnating TiO2 with a KOH solutio n and then calcining at high temperature. The photo-reduction of Cr(VI) cat alyzed by SLCs and LC was also examined. Results showed that LCs were obser ved in the surface of SLCs and they were generated by a solid-phase reactio n between KOH/K2CO3 and TiO2 at high temperature. At a solution pH of 1.0, the Cr(VI) photo-reduction showed 1/2 order kinetics in the presence or abs ence of TiO2. However, the Cr(VI) photo-reduction catalyzed by LC fitted ze ro order kinetics. In the presence of SLC with low loading amount of LC, th e Cr(VI) photo-reduction showed the same kinetics as that over TiO2. In con trast, the kinetics of Cr(VI) photo-reduction catalyzed by SLC with high lo ading amount of LC was similar to that by the unsupported LC. SLC with a ce rtain loading amount of LC exhibited enhanced catalytic activity for Cr(VI) photo-reduction. The enhanced catalytic activity was related to the electr on transfer between the support and the LC. (C) 2000 Published by Elsevier Science B.V.