Photocatalytic Reduction Of Hexavalent Chromium Research Articles

Photocatalytic reduction of hexavalent chromium in aqueous solution over titania pillared zirconium phosphate and titanium phosphate under solar radiation

The photo-reduction of hexavalent chromium was carried out varying different parameters such as pH, titania loading on zirconium phosphate (ZrP) and titanium phosphate (TiP), initial substrate concentration, irradiation time and catalyst dose. The reduction rate of chromium was favorable under acidic pH than in the alkaline pH. The dissolved oxygen imparts the minimum effect on the reduction of Cr(VI) as oxygen competes with the hexavalent chromium for the electron in the acidic solutions. Hexavalent chromium was completely reduced over titania pillared ZrP and TiP under solar radiation. This process of photo-reduction follows approximately pseudo first-order kinetics.

Photocatalytic reduction of hexavalent chromium in aqueous solution over sulphate modified titania

Samples of different crystal forms and sizes of unmodified and sulphate modified TiO 2 were prepared by varying pH, source and concentration of sulphate ion and by activating at different temperatures. Samples prepared at lower pH exhibit more surface area than that of higher pH. The percentage of photocatalytic reduction of Cr(VI) under solar radiation is higher at low pH and decreases with rise in pH of suspension. Presence of sacrificial electron donor such as EDTA enhances the photocatalytic reduction whereas presence of oxygen reduces it. Photocatalytic reduction of hexavalent chromium depends on surface area, the crystal form and particle size of TiO 2. Samples containing mixtures of anatase and rutile phases exhibit highest activity for reduction of hexavalent chromium than that of single phases.