Effect of charged boundary on electrophoresis: Sphere in spherical cavity at arbitrary potential and double-layer thickness.
The boundary effect on electrophoresis is investigated by considering a spherical particle at an arbitrary position in a spherical cavity. Our previous analysis is extended to the case where the effect of double-layer polarization can be significant. Also, the effect of a charged boundary, which yields an electroosmotic flow and a pressure gradient, thereby making the problem under consideration more complicated, is investigated. The influences of the level of the surface potential, the thickness of double layer, the relative size of a sphere, and its position in a cavity on the electrophoretic behavior of the sphere are discussed. Some results that are of practical significance are observed. For example, if a positively charged sphere is placed in an uncharged cavity, its mobility may have a local minimum as the thickness of the double layer varies. If an uncharged sphere is placed in a positively charged cavity, the mobility may have a local minimum as the position of the sphere varies. Also, if the size of a sphere is fixed, its mobility may have a local minimum as the size of a cavity varies. These provide useful information for the design of an electrophoresis apparatus.
Hsu
Jyh-Ping
JP
Department of Chemical Engineering, National Taiwan University, Taipei, 10617 Taiwan.
Chen
Zheng-Syun
ZS
Ku
Ming-Hong
MH
Yeh
Li-Hsien
LH
D000465:Algorithms; D053841:Electroosmosis / Q000379:methods*; D004586:Electrophoresis / Q000379:methods*; D008962:Models, Theoretical