Visible photocatalytic activity of metal ion doped and undoped nano ZnO for the degradation of Acidal Navy Blue 3BR

Abstract

Metal (Mn, Cu, Co) doped and undoped Nano ZnO, prepared by chemical precipitation method and calcined at 300oC was characterized by XRD, FE-SEM, FT-IR, DRS and TEM. These photo catalysts can be effectively degrade organic contaminants using visible light irradiation. Doping reduces the intra granular resistance and recombination of the photo generated electron–hole pairs. The photo activity of undoped and doped ZnO powders was evaluated by monitoring the photo-decolourization of the aqueous solutions of Acidal Navy Blue 3BR (ANB 3BR) dye under visible irradiation. The disappearance of dye molecules followed pseudo-first-order kinetics. The effect of various parameters namely, pH of the medium, catalyst loading, initial dye concentration and kinetics of photo degradation of ANB 3BR was investigated. The rate of degradation was found to be strongly influenced by all above mentioned parameters. The reduction in the chemical oxygen demand (COD) of the decolorized aqueous samples revealed a possibility of complete destruction of the organic molecules along with colour removal. Experimental data were analyzed by model equations such as Langmuir and Freundlich isotherms and it was found that the Langmuir isotherm model best fitted the adsorption data. The results showed that the doped (Mn, Cu, Co) percentage (0.25, 0.5, 0.75, 1, 1.5%) were successfully doped into the ZnO and that manganese and copper-doping reduced the photo catalytic activity of ZnO, Co doped ZnO increase the photo catalytic activity.1%, 0.75%, 0.75% of Mn, Cu, Co doped in ZnO can be used in photo catalytic experiments.