Huang Hsin Y, Keh Huan J
Department of Chemical Engineering, National Taiwan University , Taipei 10617, Taiwan, Republic of China.
J Phys Chem B. 2015 Feb 5;119(5):2040-50. doi: 10.1021/jp510448x. Epub 2015 Jan 23.
An analysis of the diffusiophoretic motion in a suspension of charged porous spheres in an electrolytic solution with a macroscopic concentration gradient is presented. Each porous particle can be a solvent-permeable and ion-penetrable charged floc or polyelectrolyte molecule, in which the densities of the fixed charges and frictional segments are constant, surrounded by an arbitrary electric double layer. The multiparticle interaction effects are considered through the use of a unit cell model, which allows the overlap of adjacent double layers. The differential equations governing the electric potential, ionic concentration, and fluid velocity distributions inside and outside the porous particle in a unit cell are linearized by assuming that the system is only slightly deviated from equilibrium and then solved as power expansions in its dimensionless fixed-charge density. A closed-form expression for the diffusiophoretic velocity of the porous particle correct to the second order of the fixed charge density is obtained from a balance between the electrostatic and hydrodynamic forces acting on it. Detailed comparisons of the results for the multiparticle diffusiophoresis obtained from the cell model with various boundary conditions are made. The effect of particle interactions on the diffusiophoresis, which is a linear combination of electrophoresis and chemiphoresis, can be significant and complicated in typical situations. Although the electrophoretic mobility of the particles decreases with an increase in the particle volume fraction, their chemiphoretic mobility is not necessarily a monotonic function of it.
本文对存在宏观浓度梯度的电解质溶液中带电多孔球体悬浮液的扩散泳动进行了分析。每个多孔颗粒可以是溶剂可渗透且离子可穿透的带电絮凝物或聚电解质分子，其中固定电荷和摩擦片段的密度是恒定的，周围环绕着任意的双电层。通过使用单胞模型考虑多粒子相互作用效应，该模型允许相邻双电层重叠。通过假设系统仅略微偏离平衡，对控制单胞中多孔颗粒内外电势、离子浓度和流体速度分布的微分方程进行线性化，然后作为其无量纲固定电荷密度的幂级数展开求解。通过作用在多孔颗粒上的静电力和流体动力之间的平衡，得到了固定电荷密度二阶精度的多孔颗粒扩散泳速度的闭式表达式。对从具有各种边界条件的单胞模型得到的多粒子扩散泳结果进行了详细比较。在典型情况下，粒子相互作用对扩散泳的影响（扩散泳是电泳和化学泳的线性组合）可能是显著且复杂的。尽管粒子的电泳迁移率随粒子体积分数的增加而降低，但其化学泳迁移率不一定是其单调函数。
