CFD modeling for optimal electrodialysis: Valorizing reject brine and carbon dioxide for sustainable solutions

Abstract

This study uses computational fluid dynamics (CFD) to model the electrodialysis (ED) process for treating saline water and capturing CO2 to form valuable products such as NaHCO3 and HCl. The ED process involves six chambers, with membranes arranged in a specific pattern to collect NaHCO3 and HCl solutions in different chambers. A 2D stationary and isothermal CFD model was developed using COMSOL to analyze the transfer of ions in the multichambered rectangular ED process. The model was developed by coupling the Nernst–Planck equation with the Navier–Stokes equation; It was then numerically solved using the finite element method. The model was found to predict concentration profiles, ionic flux profiles, electrolyte potential variations, and the velocity distribution. Using a CFD model, the impact of velocity and applied potential on flux and concentration distributions were investigated. The study also investigated how limiting current densities are affected by velocity, applied potential, and geometrical parameters. To validate the 2D model, the variation in limiting current density at different Reynolds numbers was compared with the experimental data. The proposed methodology is a valuable tool for optimizing the multichambered ED process for combined waste treatment. In addition, the results of this study provide important insights into the multichambered ED process, offering opportunities for further research and development.