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

• Published in: Desalination 2020-12, Vol.496, p.114347, Article 114347
• Main Authors: Generous, Muhammad M., Qasem, Naef A.A., Zubair, Syed M.
• Format: Article
• Language: English
• Subjects: Brackish water; Electrodialysis desalination; Equivalent NaCl; Multi-component; Standard seawater; Two-dimensional CFD model
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2020.114347

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. •Two-dimensional electrodialysis modeling of seawater and brackish water is carried out.•The validated models involve both as multi-components and equivalent NaCl solutions.•NaCl model predicts a 14% lower current density than the multi-component brackish water.•Almost the same current density is predicted by both the models for the selected seawater.•The results show that the multi-component model is very important for brackish water.