Time-dependent 2-D model for transport of species analysis in electrodialysis: Concentration profiles and fluxes

Electrodialysis (ED) is a separation process that uses an electric field to selectively transport ions through ion exchange membranes. To further advance the technology and bring it to an industrial scale, modeling ED and associated research on transport phenomena have become critical. Nowadays, most of the models present in literature are semi-empirical, which imply a large experimental campaign to properly predict the performance of ED systems. Contrary, a few models are based on Computational Fluid Dynamics to couple the hydrodynamics inside the stack and Nernst-Planck equations to model properly the ED performance. This work aims to provide further understanding of the transport of species in ED focused in the analysis of concentration profiles and fluxes, by building a 2-D computational time-dependent model. Moreover, the analysis of the concentration profiles was conducted at several positions within the stack, revealing that the ion concentration values varied depending on the location. In addition, simulations were contrasted with experimental data from a lab-scale unit. Theoretical data showed a reasonable agreement with experiments, with some discrepancies attributed to the presence of water transport.