A simple model for semipermeable membrane: Donnan equilibrium

TL;DR

This paper presents a theoretical model for macroions in electrolyte solutions separated by a semipermeable membrane, accounting for membrane thickness, surface charge, and particle correlations, with predictions matching experimental osmotic pressure data.

Contribution

It introduces a comprehensive model that explicitly includes electrostatic and size correlations, considering membrane thickness and surface charge effects.

Findings

The model accurately predicts osmotic pressure aligning with experimental data.

Macroion adsorption on the membrane surface is quantitatively analyzed.

Electrostatic and size correlations significantly influence membrane behavior.

Abstract

We study a model for macroions in an electrolyte solution confined by a semipermeable membrane. The membrane finite thickness is considered and both membrane surfaces are uniformly charged. The model explicitly includes electrostatic and size particles correlations. Our study is focused on the adsorption of macroions on the membrane surface and on the osmotic pressure. The theoretical prediction for the osmotic pressure shows a good agreement with experimental results.