Enhancement of TiO2 photocatalytic redox ability by β-cyclodextrin in suspended solutions

The enhancement of p-cyclodextrin (CD) on TiO2 photocatalytic oxidation of dye and reduction of Cr(VI) in aqueous solutions were investigated in this paper. In the system of TiO2 photocatalytic decolorization of four azo dye solutions, the addition of 4 x 10(-4) Mol/L beta-CD increased the decolorization rates of 1 x 10(-4) mol/L dye by three to seven times in the solutions containing 0.8 g/L TiO2. On the other side, in the presence of beta-CD (1 x 10(-4) to 6 x 10(-4) mol/L), the TiO2 (0.8 g/L) photocatalytic reduction rates of 1.67 x 10(-4) mol/L Cr(VI) was enhanced by 12-17 times. The enhancement is dependent on the beta-CD concentrations, TiO2 dosage and initial pH values of the solutions. The mechanism is preliminarily proposed as the formation of complexes of beta-CD with the dyes and Cr(VI) anions on the TiO2 surface. (C) 2004 Published by Elsevier B.V.