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Influence of the electrical diffuse layer and microgeometry on the effective ionic diffusion coefficient in porous media
Author(s) -
Revil A.,
Darot M.,
Pezard P. A.
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl01809
Subject(s) - diffusion , porous medium , materials science , porosity , diffusion layer , ionic bonding , diffusion equation , matrix (chemical analysis) , effective diffusion coefficient , thermodynamics , layer (electronics) , composite material , ion , chemistry , physics , medicine , economy , organic chemistry , radiology , magnetic resonance imaging , economics , service (business)
This study models the effect of the electrical diffuse layer at the pore matrix interface on ionic diffusion processes in a porous medium in presence of a concentration gradient. We find that the equation D = D f /Fø usually used to compute in steady state conditions the effective diffusion coefficient, D , of a porous medium as a function of the salt diffusion coefficient, D f , the electrical formation factor, F , and the porosity, ø, should be replaced by: D = ( D f /Fø )ξ, in the presence of an electrical diffuse layer at the pore‐matrix interface. The correction factor, ξ arises from the cross‐coupling of ionic fluxes due to electroneutrality requirement.