Electrophoresis of a Colloidal Sphere in a Spherical Cavity with Arbitrary Zeta Potential Distributions and Arbitrary Double-Layer Thickness

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• 作者：Huan J. Keh ; Tzu H. Hsieh
• 刊名：Langmuir
• 出版年：2008
• 出版时间：January 15, 2008
• 年：2008
• 卷：24
• 期：2
• 页码：390 - 398
• 全文大小：169K
• 年卷期：v.24,no.2(January 15, 2008)
• ISSN：1520-5827

文摘

The electrophoretic motion of a dielectric sphere situated at the center of a spherical cavity with an arbitrarythickness of the electric double layers adjacent to the particle and cavity surfaces is analyzed at the quasisteady statewhen the zeta potentials associated with the solid surfaces are arbitrarily nonuniform. Through the use of the multipoleexpansions of the zeta potentials and the linearized Poisson-Boltzmann equation, the equilibrium double-layer potentialdistribution and its perturbation caused by the applied electric field are separately solved. The modified Stokesequations governing the fluid velocity field are dealt with using a generalized reciprocal theorem, and explicit formulasfor the electrophoretic and angular velocities of the particle valid for all values of the particle-to-cavity size ratio areobtained. To apply these formulas, one only has to calculate the monopole, dipole, and quadrupole moments of thezeta potential distributions at the particle and cavity surfaces. In some limiting cases, our result reduces to the analyticalsolutions available in the literature. In general, the boundary effect on the electrophoretic motion of the particle isa qualitatively and quantitatively sensible function of the thickness of the electric double layers relative to the radiusof the cavity.