Photocatalytic reduction of Cr(VI) in aqueous titania suspensions exposed to concentrated solar radiation

Abstract

A laboratory scale parabolic trough collector has been tested for photocatalytic reaction application to wastewater treatment under different reaction conditions. The photocatalytic reduction of Cr(VI) to Cr(III), using TiO2 suspensions under solar irradiation, has been investigated. The influence of reaction conditions has been illustrated using an organic additive (citric acid) in varying doses and also by performing the reaction at different pH values and doses of TiO2. An attempt has also been made to investigate the reuse performance of the photocatalyst. The rate of reduction was found to increase steadily with increasing concentration of organic additive, TiO2 dose and decreasing pH. Complete reduction of Cr(VI) to Cr(III) was achieved in 2 h and very low catalyst concentration at pH 2. The reuse studies showed that the catalyst can be used 2–3 times for lower Cr(VI) concentrations.