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

Abstract The enhancement of β-cyclodextrin (CD) on TiO 2 photocatalytic oxidation of dye and reduction of Cr(VI) in aqueous solutions were investigated in this paper. In the system of TiO 2 photocatalytic decolorization of four azo dye solutions, the addition of 4 × 10 −4  mol/L β-CD increased the decolorization rates of 1 × 10 −4  mol/L dye by three to seven times in the solutions containing 0.8 g/L TiO 2 . On the other side, in the presence of β-CD (1 × 10 −4 to 6 × 10 −4  mol/L), the TiO 2 (0.8 g/L) photocatalytic reduction rates of 1.67 × 10 −4  mol/L Cr(VI) was enhanced by 12–17 times. The enhancement is dependent on the β-CD concentrations, TiO 2 dosage and initial pH values of the solutions. The mechanism is preliminarily proposed as the formation of complexes of β-CD with the dyes and Cr(VI) anions on the TiO 2 surface.