We determine the macroscopic transport properties of isotropic
microporous media by volume-averaging the local Nernst-Planck and
Navier-Stokes equations in nonisothermal conditions. In such media, the
excess of charge that counterbalances the charge deficiency of the
surface of the minerals is partitioned between the Gouy-Chapman layer
and the Stem layer. The Stem layer of sorbed counterions is attached to
the solid phase, while the Gouy-Chapman diffuse layer is assumed to have
a thickness comparable to the size of the pores. Rather than using
Poisson-Boltzmarm distributions to describe the ionic concentrations in
the pore space of the medium, we rely on Donnan distributions obtained
by equating the chemical potentials of the water molecules and ions
between a reservoir of ions and the pore space of the medium. The
macroscopic Maxwell equations and the macroscopic linear constitutive
transport equations are derived in the vicinity of equilibrium, assuming
that the porous material is deformable. In the vicinity of thermodynamic
equilibrium, the cross-coupling phenomena of the macroscopic
constitutive equations of transport follow Onsager reciprocity. In
addition, all the material properties entering the constitutive
equations depend only on two textural properties, the permeability and
the electrical formation factor. (c) 2006 Elsevier Inc. All rights
reserved.