Chapter 1.4 Measurement techniques of transport through membranes

Abstract Membrane model-independent relationships (e.g., phenomenological relationships of the thermodynamics of irreversible processes, Kedem—Katchalsky and Schlogl relationships, non-linear relationship of Kedem and Spiegler) and membrane model-dependent relationships (e.g., solution—diffusion model, fine porous membrane models such as combined viscous flow and frictional model, fixed charge and fine-porous membrane model) for transport of matter across synthetic membranes are compiled. Subsequently, the experimental determination of equilibrium properties such as membrane water content, fixed charge concentration and exchange isotherm, partition coefficients of solutes (absorption isotherm), and membrane swelling, is discussed since the equilibrium data are required for the evaluation of transport parameters from membrane model-dependent relationships. Finally, experimental methods for the determination of transport coefficients from dialysis—osmosis and hyperfiltration experiments are summarized placing emphasis on the determination and interpretation of membrane potential measurements. The characterization of hollow fibers and composite membrane systems by means of hyperfiltration experiments is also considered.