Related Experiment Video
Updated: Jul 10, 2025
08:01
Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand
Published on: September 8, 2016
8.4K
Shear-Enhanced Ion Rejection during Seawater Freezing
Yixiang Wang1, Dachuang Shi1, Gongze Liu1
1Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong.
The Journal of Physical Chemistry. B
|November 24, 2023
Summary
External shear enhances ion rejection during freeze desalination. Molecular dynamics simulations and experiments show increased shear rates improve ion separation by disrupting hydration shells and reducing the energy barrier at the ice-water interface.
Area of Science:
- Water Desalination
- Materials Science
- Physical Chemistry
Background:
- Freeze desalination relies on ion rejection from freezing seawater.
- Improving ion rejection is crucial for efficient desalination performance.
Purpose of the Study:
- To investigate the enhancement of ion rejection rate using external shear.
- To elucidate the underlying mechanisms through molecular dynamics (MD) simulations and experimental validation.
Main Methods:
- Molecular dynamics (MD) simulations were employed to model ion behavior under shear.
- Experimental freeze desalination was conducted to validate simulation findings.
- Analysis focused on ion mobility and energy barriers at the ice-water interface.
Main Results:
- Ion rejection rate increased with increasing shear rate in MD simulations.
- Shear disrupts hydration bonds between ions and water molecules.
- Increased ion mobility and reduced interface energy barrier facilitate ion diffusion away from ice.
Conclusions:
- External shear is an effective method to enhance ion rejection in freeze desalination.
- MD simulations provide mechanistic insights into shear-induced ion rejection.
- Findings offer a pathway for optimizing freeze desalination processes through external parameter control.
More Related Videos
Related Concept Videos
01:17Ion Exchange
595
Ion exchange chromatography separates charged molecules from a solution by reversibly exchanging them with mobile, or 'active', ions associated with the oppositely charged stationary phase. This method can be used to separate ions, soften and deionize water, and purify solutions. The polymers comprising the ion-exchange column are high-molecular-weight and chemically stable polymers, crosslinked to be porous and essentially insoluble. They are also functionalized with either acidic or...
595
01:09Ion-Exchange Chromatography
536
Ion-exchange chromatography, or IEC, is a technique for separating ions based on their affinity for the stationary phase. The stationary phase is a cross-linked polymer resin with covalently attached ionic functional groups. The functional groups can be either positively charged (cation exchangers) or negatively charged (anion exchangers). A cation exchanger consists of a polymeric anion and active cations, while an anion exchanger is a polymeric cation with active anions. The choice of...
536
01:12Ionic Strength: Overview
1.4K
The ionic strength of a solution is a quantitative way of expressing the total electrolyte concentration of a solution. This concept was first introduced in 1921 by two American physical chemists, Gilbert N. Lewis and Merle Randall, while describing the activity coefficient of strong electrolytes. During the calculation of ionic strength (I or μ), all the cations and anions are considered. However, the concentration (c) of an ion with a greater charge number (z) has a greater contribution...
1.4K
01:19Ionic Strength: Effects on Chemical Equilibria
1.5K
The addition of an inert ionic compound increases the solubility of a sparingly soluble salt. For example, adding potassium nitrate to a saturated solution of calcium sulfate significantly enhances the solubility of calcium sulfate. Le Châtelier's principle cannot predict this shift in the equilibrium. Instead, this could be explained in terms of changes in the effective concentration of the ions in solution in the presence of added inert salt.
In this solution, the primary...
In this solution, the primary...
1.5K
03:13Intermolecular Forces
58.5K
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen...
58.5K
01:09Colloidal precipitates
593
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
593