Salt permeation through an ionic membrane and a test of onsager reciprocity

Abstract

The salt permeation fluxes through a cation exchange membrane have been measured for NaBr, CsBr and SrBr₂ as functions of concentration. The data were obtained from determinations of forward and back fluxes by using radio-tracers.

The results have been combined with other transport properties of the same membrane to evaluate the salt conductance coefficient.

Eight independent items of transport data are now available on this membrane and it has become possible to test two of the three Onsager reciprocal relations between cross coefficients. The relations are found to be obeyed within the limits set by experimental uncertainties. These observations are taken to mean that the scheme devised for studying and interpreting membrane behaviour through linear non-equilibrium thermodynamics has been correctly carried out within the region where the linear approximation is valid.