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Theoretical and numerical analysis is made for electrophoresis of charged colloids for a
generalized situation in which the particle is considered to be polarizable and the surface
exhibits hydrophobicity. The dielectric polarization of the particle creates a nonlinear dependence
of the electrophoretic velocity on the applied electric field, and the surface hydrophobicity
amplifies the fluid convection in the Debye layer. Thus, a linear analysis is no longer applicable
for this situation. The present analysis is based on the numerical solution of the nonlinear
electrokinetic equations based on the Navier-Stokes-Nernst-Planck-Poisson equations coupled with
the Laplace equation for the electric field within the dielectric particle. The hydrophobicity of
the particle may influence its electric polarization by enhancing the convective transport of ions.
The nonlinear effects, such as double-layer polarization and relaxation, are also influenced by the
hydrophobicity of the particle surface. The electrophoresis of a soft particle with pH-regulated
polyelectrolyte layer will be introduced.
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