Electric Field-Enhanced Ion Rejection Rate in Freeze Desalination

YX Wang and BL Huang and ZG Li, CHEMPHYSCHEM, 25 (2024).

DOI: 10.1002/cphc.202400397

Freeze desalination is an appealing method for seawater desalination through freezing seawater. The percentage of ions in the liquid phase, which is termed ion rejection rate, is a critical factor affecting the performance of freeze desalination. Improving the ion rejection rate is an important topic for freeze desalination. In this work, we investigate the effects of electric fields on the ion rejection rate during the freezing of seawater through molecular dynamics simulations. It is found that the ion rejection rate increases with increasing electric field strength. The enhanced ion rejection rate is due to the reduction of the energy barrier at the ice-water interface caused by the electric field, which affects the orientation of water molecules and ion-water interactions. However, the electric field hinders the ice growth rate, which affects the productivity of freeze desalination. Nevertheless, the finding in this work offers a new idea to improve the ion rejection rate. Practically, a trade-off needs to be found to optimize the overall performance of freeze desalination. Ions tend to stay in the liquid phase during the freezing of seawater, which is termed ion rejection. This phenomenon can be used to desalinate seawater, for which the ion rejection rate is an important index. Practically, a high ion rejection rate is desired. In this work, we propose a method to enhance the ion rejection rate using external electric fields. image

Return to Publications page