Journal of Electroanalytical Chemistry, Vol.378, No.1-2, 111-116, 1994
A New Method for Determining Transport Numbers of Charged Membranes from Convective Diffusion Experiments
We present a new method for determining transport numbers of charged membranes from convective diffusion experiments. The development of concentration differences in the two bulk solutions due to the passage of an electric current (which is characteristic of conventional Hittorf methods in membrane systems) is avoided by using a convective flow opposed to the electric current. A theoretical modelling based on the Nernst-Planck equations gives both the membrane charge density and the transport number from the experimental data. The proposed method is suited for membranes porous enough to allow a hydrodynamic flow through and avoids the need for an accurate chemical analysis, since only conductometric determinations are required.