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

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 25ºc. 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).