فهرست نشریات علمی دسترسی آزاد ایران

This study aims to evaluate the photocatalytic activity of a SiO₂/ZnO nanocomposite (where the surface characterized by using XRD , EDX and SEM techniques) for the degradation of organic pollutants, using Congo red dye as a model contaminant. Photocatalytic experiments were conducted using an aqueous solution containing 0.15 g of the nanocomposite per 100 mL of a 10 mg/L Congo red solution, under UV light irradiation.The influence of several operational parameters on the photocatalytic degradation efficiency was systematically investigated, including: Effect of catalyst dosage, a concentration of 0.15 g/100 mL was found to be effective, effect of initial dye concentration, various concentrations were tested, with 10 mg/L determined to be optimal, Effect of Initial pH of the solution, The photocatalytic performance was evaluated at different pH levels, with the best degradation observed at pH 8, Effect of addition of hydrogen peroxide (H₂O₂), the effect of H₂O₂ as an oxidizing agent was assessed to enhance the degradation efficiency, Effect of light intensity ,the effect of varying UV light intensity on the degradation process was examined and, Effect of reaction temperature, the influence of temperature on the photocatalytic reaction rate was analyzed. Kinetic and thermodynamic studies were carried out to understand the mechanism of degradation. The activation energy and other thermodynamic parameters were calculated using the Arrhenius and Eyring equations. The results were as follows: Activation Energy (Ea)= 38.61 kJ·mol-1,Enthalpy of Activation (ΔH°) = 31.06 kJ·mol-1,Entropy of Activation (ΔS°)=  –0.14842 kJ·mol-1·K-1and Gibbs Free Energy of Activation (ΔG°) =  - 44.19 kJ·mol-1.The degradation process was monitored using UV-Visible spectrophotometry to assess the concentration of the dye before and after irradiation.