Photocatalytic Degradation of Methylene Blue Dye Using Silica Oxide Nanoparticles as a Catalyst

The present research deals with the development a fast and low-cost method for removing color dye from water using nanosized semiconductors SiO2 as photocatalyst. The studies of kinetic photocatalytic degradation were carried out on an aqueous solution of soluble methylene blue dye, which contained SiO2 nanoparticles and under an ultraviolet light source. Different parameters affecting the process have been studied: catalyst concentration, dye concentration, temperature, and pH of solution. The color variation was detected at three absorption bands (662, 293, and 243 nm). It was found that the dye completely degraded in 90 s, using 10 g/L SiO2 nanoparticles at 25 °C and pH 1.5 and 11.0. The adsorption of the dye well-fitted pseudo-second-order kinetic models. The Langmuir-Hinshelwood model was acquired to analyze the photocatalytic degradation process. A possible molecular mechanism for photocatalytic degradation of the dye by SiO2 nanoparticles is also given.