Electrophoresis of Porous Particles in a Concentrated alt-free Suspension
Date Issued
2009
Date
2009
Author(s)
Wu, Hsiao-Han
Abstract
In this study, we investigate numerically the electrokinetic phenomena of charged porous particle based on the pseudo-spectral method. The electrophoretic behavior of a concentrated dispersion of porous particles in a salt-free medium is analyzed theoretically. The counter-ion in solution comes from the charge-regulated surface of porous particle. We adopt respectively the Kuwabara’s unit cell model and solve the coupled electrokinetic equations those govern the electric field, the flow field and the ionic concentration field in these problems. In the results we found that, as the volume fraction and the surface charge of particle are small, the electrophoretic mobility increase with the charge linearly; however, when the charge exceeds a certain critical value, counter-ion condensation occurs and mobility will not change with the charge anymore. In addition, the mobility has local maximum due to relaxation effect. However, when the volume fraction is big, counter-ion condensation will decay as the surface charge increase. Meantime, relaxation effect still exists and lifts and postpones the mobility local maximum. In this study, we expand Ohshima’s approximate results in 2004. In addition, we compare our results with Nagasawa et al.’ which discuss the influence of polyelectrolyte’s concentration.
Subjects
electrophoresis
electrokinetic
porous particle
salt-free solution
counter-ion condensation
and relaxation effect.
Type
thesis
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