Ionic Diffusion Dynamics

Osmotic Pressure and Diffusion of Ions in Charged Nanopores.


The transport of ions and water in nanopores is of interest for a number of natural and technological processes. Due to their practically identical long straight cylindrical pores, nanoporous track-etched membranes are suitable materials for investigation of its mechanisms. This communication reports on simultaneous measurements of osmotic pressure and salt diffusion with a 24 nm pore track-etched membrane.

Due to the use of dilute electrolyte solutions (1−4 mM KCl and LiCl), this pore size was commensurate with the Debye screening length. Advanced interpretation of experimental results using a full version of the space-charge model has revealed that osmotic pressure and salt diffusion can be quantitatively correlated with electrostatic interactions of ions with charged nanopore walls. The surface-charge density is shown to increase with electrolyte concentration in agreement with the mechanism of deprotonation of weakly acidic surface groups.Moreover, a lack of significant surface-charge dependence on the kind of cation (K+ or Li+) demonstrates that binding of salt counterions does not play a major role in this system.


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Full Article:

Osmotic Pressure and Diffusion of Ions in Charged Nanopores

Supporting Documents:

  1. Time-resolved pressure-induced electric potential in nanoporous membranes: measurement and mechanistic interpretation
  2. Evaporation-driven electrokinetic energy conversion: critical review, parametric analysis and perspectives