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Study on Photocatalytic Reduction of Cr(VI) by Fluorine-Doped TiO2

To enhance the photocatalytic performance of nanoTiO2 on Cr (VI) reduction, we have prepared fluorine-doped TiO2 photocatalyst (named as F-TiO2 hereinafter) via sol-gel method. N-doped TiO2 (N-TiO2) was also prepared for comparison. XRD, BET and UV-vis DRS were used to characterize and analyze these samples. The photocatalytic activity of different photocatalysts was evaluated by Cr (VI) reduction experiments. Effects of preparation conditions, reaction kinetics and catalyst lifetime were discussed in this paper. The experimental results showed that the best preparation conditions were as follows: ammonium fluoride used as F source, F/Ti=0.1, calcination temperature=500°C and calcination time=3h. The photocatalytic reduction process conformed the first-order kinetics, and the reaction rate constant of F-TiO2 was 4 times as large as that of virgin TiO2. Characterizations also proved that F doping improved the photocatalytic activity of TiO2.