Ionic transport in porous media for high zeta potentials

Ionic transport coefficients are numerically calculated in various porous media for high zeta potentials ζ by solving the Poisson–Boltzmann, the Stokes, and the convection–diffusion equations on the pore scale. Theoretical formulae for the simple case of a plane Poiseuille flow are derived in this limit. These formulae, when expressed in terms of the characteristic length Λ, provide an excellent estimate of the ionic transport coefficients whatever the porous medium and whatever the value of ζ.

For various porous media, the coefficients coupling the external macroscopic gradients and the macroscopic solute fluxes are shown to follow the semianalytical solution derived for a plane Poiseuille flow (solid lines).Figure optionsDownload as PowerPoint slide