Enhanced Oxidation of Azo Dye Using Ag-SiO2 Nanoparticle and Peroxydisulfate and Kinetic Study

Abstract

Present work investigates the capability of oxidative treatment process in the presence of nano silver doped on silicate particles for decolorization of a widely used azo dye, C.I. Direct Blue 129 (DB129) in water samples. Solutions with initial concentration of 20 mgL-1 of dye, within the range of generic concentration in textile wastewaters, were treated under ambient conditions of initial pH of 6.7 and temperature of 25º<em>c</em>. The operational parameters evaluation including dye and peroxydisulfate concentration, initial pH, nanoparticles dosage and reaction time was studied in an endeavor to reach the higher dye removal efficiency. Subsequently, a removal more than 90% of dye was attained by applying the optimal operational conditions as follow: 0.4 g of catalyst, 20 mgL^-1 of dye, 5 mM of peroxydisulfate and initial pH of 6.7 in 35 min. Moreover, kinetic study for various parameters in several conditions for treatment process was investigated. Pseudo- first-order reaction rate constants were calculated for the systems. The morphology and crystal structure of Ag-SiO₂ nanoparticles were characterized by means of Transmission Electron Microscope (TEM).