Diffusioosmosis of nonelectrolyte solutions in a fibrous medium
Resource
Colloids and Surfaces A: Physicochemical and Engineering Aspects 221 (1-3): 175-183
Journal
Colloids and Surfaces A: Physicochemical and Engineering Aspects
Journal Issue
221
Pages
175-183
Date Issued
2003
Date
2003
Author(s)
Wei, Yeu K.
Abstract
The steady diffusioosmotic flow of a fluid solution of an uncharged solute in the fibrous porous medium constructed by a homogeneous array of parallel circular cylinders is analytically studied. The imposed solute concentration gradient is constant and can be oriented arbitrarily with respect to the axes of the cylinders. The range of the interaction between the solute molecules and the cylinder surfaces is assumed to be small relative to the radius of the cylinders and to the gap thickness between two neighboring cylinders, but the effect of polarization of the mobile solute in the thin diffuse layer surrounding each cylinder caused by the strong adsorption of the solute is taken into account. Through the use of a unit cell model, the appropriate equations of conservation of mass and momentum are solved for each cell, in which a cylinder is envisaged to be surrounded by a coaxial shell of the fluid solution. Analytical expressions for the diffusioosmotic velocity of the bulk fluid as functions of the porosity of the ordered array of cylinders are obtained for various cases. Comparisons of the results of the cell model with different conditions at the outer boundary of the cell are made. In the limit of maximum porosity, these results can be interpreted as the diffusiophoretic velocity of an isolated circular cylinder caused by the imposed solute concentration gradient. © 2003 Elsevier Science B.V. All rights reserved.
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journal article
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