This paper discusses the little-known fact that Donnan’s equilibrium criteria established over 100 years ago neglected coupling between ion concentrations and osmotic pressure. Such can be treated based on general thermodynamic considerations including solvent equilibrium, leading to a membrane potential consists of not only classical Donnan term but also an additional due pressure, existence e...

The recently developed modified Donnan (mD) model provides a simple and useful description of the electrical double layer in microporous carbon electrodes, suitable for incorporation in porous electrode theory. By postulating an attractive excess chemical potential for each ion in the micropores that is inversely proportional to the total ion concentration, we show that experimental data for ca...

We present a method that enables the direct simulation of Donnan equilibria. The method is based on a grand-canonical Monte Carlo scheme that properly accounts for the unequal partitioning of small ions on the two sides of a semipermeable membrane, and can be used to determine the Donnan electrochemical potential, osmotic pressure, and other system properties. Positive and negative ions are con...

We establish an appropriate thermodynamic framework for determining the optimal genome length in electrostatically driven viral encapsidation. Importantly, our analysis includes the electrostatic potential due to the Donnan equilibrium, which arises from the semipermeable nature of the viral capsid, i.e., permeable to small mobile ions but impermeable to charged macromolecules. Because most mac...

We measured the activity of Ca2+, Na+, K+, and Cl- with ion-selective electrodes after equilibrium dialysis of solutions with different albumin concentrations. The calculated Donnan ratio was the same for all ions in the same solution and increased with the albumin concentration, as predicted by the Donnan theory. The Donnan distribution ratio for Ca2+ was similar, as determined with instrument...

Limitations have been detected in a recently published method for macroion valence determination by an ultracentrifugal procedure for quantifying the Donnan distribution of small ions in macroion solutions dialyzed against buffer supplemented with chromate as an indicator ion. The limitation reflects an implicit assumption that sedimentation velocity affords an unequivocal means of separating e...

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