Removal of methylene blue from aqueous solution using nano-TiO2/UV process: Optimization by response surface methodology

This work describes the photocatalytic removal of methylene blue from aqueous solution by titanium dioxide nanoparticles under ultraviolet irradiation in a batch system. The effect of operational parameters such as irradiation time, nano titanium dioxide dosage, pH and initial methylene blue concentration were analyzed and optimized by response surface methodology in the nano titanium dioxide/ultraviolet irradiation process. As results, the predicted values were best fitted with the experimental data R^2 0.9736. The maximum removal efficiency was in the following conditions: irradiation time of 31.5 min, nano titanium dioxide dosage of 1.19 g L^-1, pH of 7.8 and initial methylene blue concentration of 4.5 mg L^-1. Under the optimized status, the removal yield was obtained more than 80. Carrying out the experiment under this optimum condition resulted in the same removal efficiency, which indicated the success and suitability of the central composite design model for the optimization of the process.