Electrophoretic mobility and electric conductivity of suspensions of charge-regulating colloidal spheres
Electrophoretic mobility and electric conductivity of suspensions of charge-regulating colloidal spheres
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DOI：
10.1021/la0115435
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发表时间：
2002-06-11
期刊：
影响因子：
3.9
通讯作者：
Ding, JM
中科院分区：
文献类型：
--
作者：
Keh, HJ;Ding, JM
本文对具有任意厚度电双层的球形电荷调节粒子单分散悬浮液的电泳性和电导性进行了分析研究。粒子表面离子基团的缔合/解离反应引起的电荷调节可用线性化调节模型来近似，该模型描述了表面电荷密度与表面电势之间的线性关系。采用单胞模型考虑了粒子间相互作用的影响，并允许相邻粒子的双层重叠。在假设系统只有轻微偏离平衡的情况下，将控制电势分布、离子浓度分布和单电池中粒子周围的电解质溶液中的流体流场的电动力学方程线性化。采用正则摄动法，以粒子的平衡表面势为小扰动参数，对线性化方程进行了求解。推导了电荷调节球的电泳率和悬浮液的电导率的闭合公式。结果表明，电荷调节效应对电泳迁移率和有效电导率的影响始于平衡表面电势的前级，这取决于悬浮液的调节特性，并且对单位电池外表面指定的电势的边界条件非常敏感。
An analytical study of electrophoresis and electric conduction in a monodisperse suspension of spherical charge-regulating particles with an arbitrary thickness of the electric double layers is presented. The charge regulation due to association/dissociation reactions of ionogenic functional groups on the particle surface is approximated by a linearized regulation model, which specifies a linear relationship between the surface charge density and the surface potential. The effects of particle interactions are taken into account by employing a unit cell model, and the overlap of the double layers of adjacent particles is allowed. The electrokinetic equations that govern the electric potential profile, the ionic concentration distributions, and the fluid flow field in the electrolyte solution surrounding the particle in a unit cell are linearized assuming that the system is only slightly distorted from equilibrium. Using a regular perturbation method, these linearized equations are solved with the equilibrium surface potential of the particle as the small perturbation parameter. Closed-form formulas for the electrophoretic mobility of the charge-regulating spheres and for the electric conductivity of the suspension are derived. Our results indicate that the charge regulation effects on the electrophoretic mobility and the effective conductivity appear starting from the leading order of the equilibrium surface potential, which depends on the regulation characteristics of the suspension, and are quite sensitive to the boundary condition for the electric potential specified at the outer surface of the unit cell.