A New Step-based Photoreactor for Degradation of Acid Dye using N-TiO2-P25-coated Ceramic Foam under Visible Light

Abstract

In the present study, a new step-based photoreactor was presented to investigate the degradation of Acid Red 73 under visible light irradiation. Four N-TiO₂-coated alumina foams prepared by the modified sol-gel process were arranged in each step as photocatalyst. The experimental design methodology was employed to assess the interaction between the operational parameters in the step-based photoreactor. The effect of the initial dye concentration and the dipping time of the support on degradation efficiency is highly significant. The optimal values were found to be a flow rate of 587.96 mL/min, an initial dye concentration of 5.82 mg/L, an H₂O₂ concentration of 1.26 mg/L and the dipping time of 43 min. The 94% reduction in the chemical oxygen demand (COD) value indicated the effective mineralization of organic reactants of the solution. The kinetics analysis shows that the photocatalytic removal of Acid Red 73 in such photoreactor follows a first-order model. It was also shown that the proposed modified photoreactor could improve the degradation efficiency compared to the conventional step photoreactor. Results indicate that there is a potential to develop thin film coatings integrated into this new step-based photoreactor, allowing an effective photocatalytic process.