Diffusiophoresis of Concentrated Suspensions of Spherical Particles with Distinct Ionic Diffusion Velocities
Resource
The Journal of Physical Chemistry B 111 (10): 2533-2539
Journal
The Journal of Physical Chemistry B
Journal Volume
111
Journal Issue
10
Pages
2533-2539
Date Issued
2007
Date
2007
Author(s)
Abstract
The diffusiophoresis of a concentrated spherical dispersion of colloidal particles subject to a small electrolyte gradient is analyzed theoretically for an arbitrary zeta potential and double layer thickness. In particular, the influence of the difference in the diffusivities of cations and anions is discussed. A unit cell model is used to simulate a spherical dispersion, and a pseudospectral method is adopted to solve the equations governing the phenomenon under consideration. We show that, as in the case of an infinitely dilute dispersion, when the diffusivities of cations and anions are different, the diffusiophoretic mobility is no longer an even function of the zeta potential or double layer thickness. In contrast to the case of identical diffusivity of cations and anions, a local electric field is induced in the present case due to an unbalanced charge distribution between higher and lower concentration regions. Depending upon the direction of this induced electric field, the diffusiophoretic mobility can be larger or smaller than that for the case of identical diffusivity. The diffusiophoretic mobility is influenced mainly by the induced electric field arising from the difference in the ionic diffusivities, the concentration gradient, and the effect of double layer polarization.
Type
journal article
File(s)![Thumbnail Image]()
Loading...
Name
33.pdf
Size
239.19 KB
Format
Adobe PDF
Checksum
(MD5):4a93c22d6375baefe87872a2193867ef