Performance evaluation of gas-sparged photocatalytic reactor for dye wastewater treatment: Parametric optimization and cost analysis

Abstract

Synthetic dyes, such as methyl violet, are widely used in industrial processes and are resistant to conventional wastewater treatment methods due to their complex molecular structure, toxicity, and persistence in aquatic environments. These pollutants pose significant risks to human health and ecosystems, creating an urgent need for advanced treatment technologies. Developing an efficient, cost-effective, and scalable solution for complete dye degradation remains a critical challenge in wastewater management. This study investigates the performance of a gas-sparging-assisted UV/TiO 2 photocatalytic system for the efficient degradation of methyl violet dye in aqueous solutions. The system was optimized using Response Surface Methodology (RSM) for five critical parameters: reaction time, pH, initial dye concentration, catalyst load, and gas velocity. Optimal conditions of 13.6 min reaction time, pH 7, 10.5 mg/L dye concentration, 0.66 g/L catalyst loading, and 1.17 cm/s gas velocity achieved a maximum dye removal efficiency of 91.58 %. Comparative analysis with UV photolysis revealed superior performance of UV/TiO 2 photocatalysis, attaining 90.2 % removal in 14 min versus 77.1 % removal in 35 min for photolysis, with significantly reduced energy consumption (0.177 kWh vs. 0.886 kWh) and operating costs ($0.107 vs. $0.483 per gram of dye removed). The enhanced efficiency of UV/TiO 2 photocatalysis is attributed to the generation of reactive oxygen species (ROS) and improved mass transfer facilitated by gas sparging. The findings demonstrate the potential of gas sparging-assisted UV/TiO 2 photocatalysis as a cost-effective and scalable solution for industrial wastewater treatment, offering higher efficiency, reduced operational costs, and eco-friendly processing.