Electrodialysis to concentrate high-salinity solutions: The matching relation between cation- and anion-exchange membranes

The effect of the matching relation between the cation and anion exchange membranes on the electrodialysis (ED) concentration performance was investigated through evaluating the salt flux, water flux, the flux ratio of salt to water and the salt content of the ED concentrate. Results indicate that the water uptake of the cation exchange membrane (CEM) is a key factor for the ED concentration performance when the ion exchange capacity of CEM has a feasible value; while for the anion exchange membrane (AEM), the ion permeability maybe is more important compared with the ion exchange capacity and the water uptake for the ED concentration performance. Besides, CEM has a greater significance for the ED concentration performance compared with AEM when both membranes have a relatively high ion permeability.