The significance of modeling electrodialysis desalination using multi-component saline water

This paper focuses on electrodialysis (ED) desalination modeling of standard seawater and brackish water as a multi-component and equivalent NaCl solutions. Experimentally validated two-dimensional models are developed based on ions separation through a cell pair of ED. Nernst-Planck equation is integrated with Navier-Stokes equations to carry out modeling using the COMSOL program. The results show that the multi-component model is important for the selected brackish water separation, while it is not significant for the investigated seawater. NaCl model predicts a little higher (~1%) current density than the standard multi-component seawater while that is lower (~14%) for a multi-component brackish water, indicating that the cell pair resistant of multi-component brackish water is different from that of equivalent NaCl solution. Ionic concentration and flux (total, migrative, and diffusive) profiles for the standard seawater (Na+, Cl−, Mg2+, SO42−, K+, Ca2+, F−, Br−, and HCO3−), a multi-component brackish water (Na+, Cl−, Mg2+, SO42−, K+, Ca2+, F−, NO3−, and HCO3−), and equivalent NaCl solutions are represented and compared. This study recommends that the NaCl model could be used for the seawater ED model, while the multi-component ED model is preferred for brackish water. Since ED systems are highly recommended for brackish water, the multi-component ED-model is needed.