Visible Light Active Fe-doped TiO2 for the Oxidation of Arsenite to Arsenate in Drinking Water

Abstract

The aim of this work was to study photocatalysts based on Titania doped with Fe, active in the presence of visible light and effective in the oxidation of As(III) to As(V). Fe-doped TiO2 photocatatysts were prepared using sol-gel method and characterized by different techniques, such as XRD, UV-Vis DRS and Raman spectroscopy. Photocatalytic experiments were carried out using a cylindrical photoreactor irradiated with a strip of visible-LEDs (nominal power: 10W) with emission in the range 400 - 600 nm. Aqueous samples containing 6 mg L-1 of As(III) were used in photocatalytic experiments. Chemical-physical characterization results evidenced that the doping of TiO2 with Fe induced a decrease of band gap value from 3.2 eV to 2.9 eV, thus making the photocatalyst active under visible light. Consistently with the characterization results, the semiconductor Fe-doped TiO2 exhibited good photoactivity in the visible light driven tests: the complete oxidation of As(III) to As(V) took place after only 30 min of irradiation in distilled water and after 60 min in drinking water.