Effect of a charged boundary on electrophoresis: A sphere at an arbitrary position in a spherical cavity
Resource
Journal of Colloid and Interface Science 310 (1): 281-291
Journal
Journal of Colloid and Interface Science
Journal Volume
310
Journal Issue
1
Pages
281-291
Date Issued
2007
Date
2007
Author(s)
Abstract
The effect of the presence of a charged boundary on the electrophoretic behavior of a particle is investigated by considering a sphere at an arbitrary position in a spherical cavity under conditions of low surface potential and weak applied electric field. Previous analyses are modified by using a more realistic electrostatic force formula and several interesting results, which are not reported in the literature, are observed. We show that the qualitative behavior of a particle depends largely on its position, its size relative to that of a cavity, and the thickness of the electric double layer. In general, the presence of a cavity has the effect of increasing the conventional hydrodynamic drag on a particle through a nonslip condition on the former. Also, a decrease in the thickness of the double layer surrounding a sphere has the effect of increasing the electrostatic force acting on its surface so that its mobility increases. However, this may not be the case when an uncharged particle in placed in a positively charged cavity, where the electroosmotic flow plays a role; for example, the mobility can exhibit a local maximum and the direction of electrophoresis can change. © 2007 Elsevier Inc. All rights reserved.
Type
journal article
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