Photocatalytic degradation of methyl orange and toluidine blue using advanced oxidation method

Abstract

Dyes being a major pollutant of water worldwide needs special attention to be effectively degraded. The photochemical technique among the applied treatment methods is considered to be the most valuable technique involving oxidative degradation processes. In this study catalytic oxidation of toluidine blue and methyl orange dyes was studied under UV light irradiation using un-doped and metal-doped TiO2. For doping 1% of Co, Ni and Zn were added to pure titania. Characterization of un-doped and metal-doped TiO2 catalysts were carried out using energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and X-ray diffraction (XRD). EDX studies show the presence of doped metals in the composition of doped titania. SEM and XRD analysis revealed that titania is in dispersed form as well as also forms agglomerates and exhibits anatase phase, respectively. Initial dye concentrations, pH and time effects were investigated to determine optimum conditions for maximum dye degradation. An increase in degradation was observed with increase in light exposure and catalyst amount. An efficient degradation of methyl orange and toluidine blue dyes up to 96% and 98% took place at pH 2 and 11, respectively with doped titania. In the absence of light source up to 3%, 5%, 7% and 10% of dye solution was adsorbed on simple and Co, Ni and Zn doped titania respectively. The doped titania proved to be an efficient photocatalyst for dye removal from aqueous samples as compared to simple titania.