Osmosis in a minimal model system

Thomas W. Lion*, Rosalind J. Allen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Osmosis is one of the most important physical phenomena in living and soft matter systems. While the thermodynamics of osmosis is well understood, the underlying microscopic dynamical mechanisms remain the subject of discussion. Unravelling these mechanisms is a prerequisite for understanding osmosis in non-equilibrium systems. Here, we investigate the microscopic basis of osmosis, in a system at equilibrium, using molecular dynamics simulations of a minimal model in which repulsive solute and solvent particles differ only in their interactions with an external potential. For this system, we can derive a simple virial-like relation for the osmotic pressure. Our simulations support an intuitive picture in which the solvent concentration gradient, at osmotic equilibrium, arises from the balance between an outward force, caused by the increased total density in the solution, and an inward diffusive flux caused by the decreased solvent density in the solution. While more complex effects may occur in other osmotic systems, our results suggest that they are not required for a minimal picture of the dynamic mechanisms underlying osmosis. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4770271]

Original languageEnglish
Article number244911
Number of pages9
JournalThe Journal of Chemical Physics
Volume137
Issue number24
DOIs
Publication statusPublished - 28 Dec 2012

Keywords

  • OSMOTIC-PRESSURE
  • SOLVENT TENSION
  • COMPUTER-SIMULATION
  • REVERSE-OSMOSIS
  • ION-TRANSPORT
  • FORUM
  • DIFFUSION
  • WATER
  • SIZE

Fingerprint

Dive into the research topics of 'Osmosis in a minimal model system'. Together they form a unique fingerprint.

Cite this