Photocatalytic reduction of Cr(VI) in aqueous solutions by UV irradiation with the presence of titanium dioxide

The reduction of Cr(VI) in aqueous solution by UV/TiO2 reduction process wa s studied under various solution pH values, TiO2 dosages, light intensities , dissolved oxygen levels and other operating conditions. The reduction rat es of Cr(VI) by photocatalytic-induced elections were significantly higher for acidic solutions than those for alkaline solutions. Increasing the ligh t intensity would drastically increase the reduction rate of Cr(VI), but wa s ultimately influenced by the amount of TiO2 present in solutions. The pre sence of dissolved oxygen had minimum effect on the reduction of Cr(VI) by UV/TiO2 process in acidic solutions. The presence of ethanol might act as s cavenger for holes and promoted the photocatalytic reduction of Cr(VI) by e lectrons. The Cr(VI) adsorbed on the surface of TiO2 particles was observed to be photoreduced to Cr(III) almost completely. (C) 2000 Elsevier Science Ltd. All rights reserved.