Enhancing Ion Rejection Rate Using High-Purity Ice Layer in Vibration-Assisted Freeze Desalination

Most freezing desalination technologies suffer from low ion rejection rates and require multiple freezing cycles to produce drinking water. For vibration-assisted freeze desalination developed previously, two freezing cycles are needed to achieve potable water generation. To further enhance the ion rejection rate to produce drinking water through single freezing cycle, we propose a method where an initial high-purity ice layer is formed by controlling the surface temperature. Experiments and molecular dynamics (MD) simulations show that this high-purity ice layer can enhance the ion rejection rate in the ice formed at the later stage and potable water can be produced through one freezing cycle. Furthermore, the ice growth rate is also improved, reaching 4.7 kg/m²/h. The underlying mechanisms are explored through MD simulations using the energy barrier for ion migration across the ice-water interface, molecular structure of the high-purity ice layer, and the stability of the hydrogen bonds at the interface.