Ionic flows through a single homogeneous membrane : A thermodynamic analysis.

The Kedem-Katchalsky equation for the flow of a mono-monovalent salt through a highly charged permselective membrane is given as a first order expansion of a single integral of the Kirkwood-Bearman-Spiegler equations. The integration is performed under the assumption that the partial frictional coefficientsζ ij are concentration independent. Conditions for the validity of the expansion are presented. A close relationship to the Goldman equation is demonstrated. If impermeable salts are present in the bathing solutions, the Kedem-Katchalskypractical parameters ω, σ, and τ1 may be ill-defined. Nevertheless, an ionic flow equation of similar form, but of significant difference, can be derived for this situation. The Kedem-Katchalsky equation for salt flow is a special case of this more general equation.