Pair Interaction in Electrophoresis of Charged Porous Particles Moving along Their Centerline
|關鍵字:||電泳現象;多孔膠體粒子;粒子間交互作用;極化效應;電雙層重疊;擬譜方法;electrophoresis;charged porous particles;particle interactions;polarization effect;double-layer overlap;pseudo-spectral method||公開日期:||2012||摘要:||本研究以數值方法探討兩顆帶電多孔粒子間相互作用對電泳動度的影響,其中包含電雙層極化效應和電雙層重疊,且電雙層厚度和多孔粒子帶電量可任意。在外加弱電場假設下,高度耦合的電動力學方程組如電位、離子濃度和流場方程式將以微擾法線性化,並以 Chebyshev 擬譜方法求解線性化後的電動力學方程組。
Electrophoresis of two charged porous spheres moving along their line of centers is investigated theoretically, where overlapping and polarization effect of electric double layers are both taken into account. The thickness of electric double layer and fixed charge density of porous spheres are arbitrary. The coupling equations of electric potential, ion concentration, and flow field are linearized by assuming that the external electric field is weak. A pseudo-spectral method based on Chebyshev polynomials is applied to numerically solve the resulting electrokinetic equations. To clarify the effect of particle interactions on the electrophoretic mobility, the effects of key parameters are examined such as the double layer thickness, fixed charge density, friction coefficient of porous particles, and surface distance between particles. The most curial finding, besides the non-zero interactions between identical particles, is that particle mobility decreases as double layer of two particles touched due to the polarization effect on the role of electric interactions. More interesting findings is that particle mobility may lower than that of the single one when high double layer overlapping is consideration. These findings was not investigated in the corresponding studies of two particle interactions where overlapping of electric double layers or polarization effect is neglected, indicating the importance of these two factors. Particle interactions between two charged porous particles can be used to describe homogeneous concentrated suspensions of polyelectrolyte in a fundamental aspect of colloid science.
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