Photocatalytic Degradation and COD Removal for Indigo Carmine Dye Using aqueous Suspension of Zinc Oxide

This paper reports on photocatalytic decolorization of a hazardous indigo carmine dye solution. The photocatalytic decolorization was carried out in the presence of the catalyst ZnO. The effect of catalyst dose, pH and initial dye concentration on the degradation process has been assessed. The aqueous dye solution was degraded in a photochemical reactor in the presence of UV light (365nm) along with suspended ZnO particles. 100 ml of dye solution (25ppm) was subjected to degradation under UV light. Different concentrations of ZnO photocatalyst (0.25, 0.50, 0.75, 1.0, and 1.25 g/L), different pH values (4, 7, 9 and 11) and different concentrations of indigo carmine dye (5, 10, 25, 50, 100 ppm) were employed for the present study. The decolorization rate of the hydrolysed dye solution was higher than that of the unhydrolysed dye solution.The chemical oxygen demand (COD) reduction at optimum conditions was examined. The decolorization of the dye was confirmed from the disappearance of peak at 608 nm.