Related Experiment Video
Updated: Jun 15, 2026
11:55
Membrane Transport Processes Analyzed by a Highly Parallel Nanopore Chip System at Single Protein Resolution
Published on: August 16, 2016
Ion Rejection by Nanoporous Membranes in Pressure-Driven Molecular Dynamics Simulations
1Sandia National Laboratories, MS 1415 and 0895, Albuquerque, NM 87185, USA.
Journal of Computational and Theoretical Nanoscience
|March 12, 2010
Summary
Molecular dynamics simulations show that nanopores can partially reject chloride ions (Cl(-)) from saltwater solutions. Ion permeation is driven by water flux, influenced by ion-pairing and pore charge.
Area of Science:
- Physical Chemistry
- Materials Science
- Nanotechnology
Background:
- Nanopore technology is crucial for filtration and separation processes.
- Understanding ion transport through nanopores is key for desalination and biological applications.
- Molecular dynamics simulations provide atomistic insights into complex fluid behavior at the nanoscale.
Purpose of the Study:
- To investigate chloride ion (Cl(-)) rejection in a dipole-lined nanopore using pressure-driven non-equilibrium molecular dynamics (MD) simulations.
- To elucidate the mechanisms governing ion permeation and rejection in nanopores under varying conditions.
- To explore the impact of pore lining charges and water flux on ion transport.
Main Methods:
- Non-equilibrium molecular dynamics (MD) simulations were employed.
- A 1.0 M NaCl electrolyte was driven through a 12 Å diameter dipole-lined nanopore.
- Potential of Mean Force (PMF) calculations were used to determine energy barriers for ion permeation.
Main Results:
- Partial Cl(-) rejection (70-80%) was achieved at ~68 atm pressure.
- Ion rejection ratio decreased with increasing water flux.
- A 6.4 kcal/mol energy barrier for Cl(-) permeation was observed, with permeation driven by water flux.
- Na(+)-Cl(-) ion-pairing within the pore significantly influenced Cl(-) permeation.
- Negatively charged pores also showed significant Cl(-) permeation under pressure.
Conclusions:
- Nanopore performance in ion rejection is sensitive to water flux and pore characteristics.
- Dynamical effects, including water flux and ion-pairing, play a critical role in overcoming energy barriers for ion permeation.
- Tailoring nanopore surface chemistry and applying sufficient pressure are potential strategies for controlling ion transport.
Related Concept Videos
02:40Osmosis and Osmotic Pressure of Solutions
A number of natural and synthetic materials exhibit selective permeation, meaning that only molecules or ions of a certain size, shape, polarity, charge, and so forth, are capable of passing through (permeating) the material. Biological cell membranes provide elegant examples of selective permeation in nature, while dialysis tubing used to remove metabolic wastes from blood is a more simplistic technological example. Regardless of how they may be fabricated, these materials are generally...
01:26Osmotic Pressure
Osmosis is a process where solvent molecules move toward a solution through a semipermeable membrane. As the solution dilutes due to the entry of solvent, it expands. This expansion increases the hydrostatic pressure of the solution. When the hydrostatic pressure equals the osmotic pressure, osmosis stops.Osmotic pressure, denoted by Π, is the minimum pressure needed to prevent the solvent from passing into the solution by osmosis. The van 't Hoff equation calculates the osmotic pressure of an...