Chiang Chia C, Keh Huan J
Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan.
Electrophoresis. 2015 Dec;36(24):3002-8. doi: 10.1002/elps.201500316.
The transient electrophoretic response of a homogeneous suspension of spherical particles to the step application of an electric field is analyzed. The electric double layer encompassing each particle is assumed to be thin but finite, and the effect of dynamic electroosmosis within it is incorporated. The momentum equation for the fluid outside the double layers is solved through the use of a unit cell model. Closed-form formulas for the time-evolving electrophoretic and settling velocities of the particles in the Laplace transform are obtained in terms of the electrokinetic radius, relative mass density, and volume fraction of the particles. The time scale for the development of electrophoresis and sedimentation is significantly smaller for a suspension with a higher particle volume fraction or a smaller particle-to-fluid density ratio, and the electrophoretic mobility at any instant increases with an increase in the electrokinetic particle radius. The transient electrophoretic mobility is a decreasing function of the particle volume fraction if the particle-to-fluid density ratio is relatively small, but it may increase with an increase in the particle volume fraction if this density ratio is relatively large. The particle interaction effect in a suspension on the transient electrophoresis is much weaker than that on the transient sedimentation of the particles.
分析了球形颗粒均匀悬浮液对电场阶跃施加的瞬态电泳响应。假设围绕每个颗粒的双电层薄但有限，并考虑其中动态电渗的影响。通过使用单胞模型求解双电层外流体的动量方程。根据电动半径、相对质量密度和颗粒体积分数，得到了拉普拉斯变换中颗粒随时间变化的电泳速度和沉降速度的闭式公式。对于颗粒体积分数较高或颗粒与流体密度比更小的悬浮液，电泳和沉降发展的时间尺度显著更小，并且在任何时刻的电泳迁移率都随电动颗粒半径的增加而增加。如果颗粒与流体密度比相对较小，瞬态电泳迁移率是颗粒体积分数的递减函数，但如果该密度比相对较大，它可能随颗粒体积分数的增加而增加。悬浮液中颗粒间相互作用对瞬态电泳的影响远弱于对颗粒瞬态沉降的影响。
