Electrochemical characterization of positively and negatively charged membranes is performed
by analyzing membrane potential values on the basis of the Teorell–Meyer–Sievers (TMS)
model. This analysis allows the separate estimation of Donnan (interfacial effects) and diffusion
(differences in ions transport through the membrane) contributions, and it permits the evaluation
of the membrane’s effective fixed charge concentration and the transport number of the ions in the
membrane. Typical ion-exchange commercial membranes (AMX, Ionics or Nafion) are analyzed,
though other experimental and commercial membranes, which are derived from different materials
and have diverse structures (dense, swollen or nanoporous structures), are also considered. Moreover,
for some membranes, changes associated with different modifications and other effects (concentration
gradient or level, solution stirring, etc.) are also analyzed.