Determination of Ionic Diffusion Coefficients in Ion?Exchange Membranes: Strong Electrolytes and Sulfates with Dissociation Equilibria

Ionic diffusion coefficients in the membrane are needed for modelling of ion transport ion-exchange membranes (IEMs) with Nernst-Planck equation. We have determined ionic Na+, OH?, H+, Cl?, SO42?, NaSO4?, and HSO4? from experiments dilute NaCl, NaOH, HCl, Na2SO4, H2SO4 solutions through IEMs conductivity measured these solutions, using electrochemical impedance spectroscopy. The order fluxes across anion-exchange is found to be as H2SO4>HCl>NaCl>Na2SO4>NaOH, whereas cation-exchange it was NaOH>NaCl>Na2SO4?H2SO4. Special attention given sulfates because partial dissociation bisulfate which makes use Nernst-Hartley equation, that is, splitting electrolyte coefficient into its contributions, impossible. expression taking account equilibrium has been derived corresponding Fick equation integrated. In addition, sulfates, finite element simulations COMSOL Multiphysics, applying a homogeneous model, were done give estimates their coefficients. This work offers convenient approach finding various ions inside IEMs.