Comparison of Membrane Permeation Models

Abstract

The main purpose of a membrane permeation equation is the reliable prediction of the behavior of membrane separation systems. An optimum permeation model preferably uses no system-related properties, but rather physical and thermodynamic data, because then a larger predictive capability is achieved with minimum experimental effort. In the IT-based equations the phenomenological coefficients, which are system-related, must be determined experimentally. These coefficients were found to be dependent on concentration and composition, probably due to the fact that the Onsager relations, applied in the derivation of the IT-membrane equations, are not valid. As a consequence, it is problematic to find empirical correlations for the prediction of the coefficients and, if so, then only at the expense of laborious effort.