Abstract: The effect of fluoride ion on the photocatalytic degradation of sulforhodamine B (SRB) on P25 and TiO2/bentonite under UV light irradiation was studied. The results of UV-Vis spectra detection showed that lower pH value lead to higher photodegradation rate in the absense of fluoride ion. And if pH value is fixed, the more the fluoride ion concentration, the faster the reaction rate will be. On TiO2/bentonite catalyst, when fluoride ion concentration reaches a definite value, its reaction rate will not change. The effect of fluoride ion on the production of H2O2 on P25 is different fromthat on TiO2/bentonite. Superoxide radical and hydroxyl radical were detected by electron paramagnetic resonance (EPR) technique. The effects of fluoride ion on these two systems are different. These phenomena may be caused by the special structures of TiO2/bentonite, which is a pillared structure with a large BET surface area and a particle size of about 57.9 nm by XRD and TEM. TiO2/bentonite catalyst was used for 11 cycles continuously, and its photocatalytic reactivity was stable. This phenomenon shows that TiO2/bentonite catalysts are easier to be separated from a dispersion systemand their stability is good. It is a promising catalyst.

Key words: TiO2/bentonite catalysts, Sulforhodamine B, UV light irradiation, Fluoride ion