Gibbs' dividing surface between a fixed-charge membrane and an electrolyte solution. Application to electrokinetic phenomena in charged pores
Gibbs' dividing surface between a fixed-charge membrane and an electrolyte solution. Application to electrokinetic phenomena in charged pores
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DOI：
10.1021/la980773p
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发表时间：
1999-09-14
期刊：
影响因子：
3.9
通讯作者：
Aguilella-Arzo, M
中科院分区：
文献类型：
--
作者：
Aguilella, VM;Pellicer, J;Aguilella-Arzo, M
两相边界的吉布斯模型包括用一个分界面替换有限界面区域，其中系统的属性逐渐变化，该分界面充当零体积的第三相，其中某些量值突然变化。这种热力学概念最近被应用于固定电荷膜和电解质溶液之间的平面界面。（1）抗衡离子随着距带电表面距离的不断减少被阶跃函数取代，因此扩散双层理想地由耗尽所有共离子的带电区域表示。这里分析了圆柱形几何形状，并通过提出稍微不同的离子浓度阶跃函数来重新审视平面情况。从溶液中离子的玻尔兹曼分布出发，获得了两种几何形状中带电界面和分界面之间距离的简单公式。为了将此模型应用于带电微孔膜，给出了由相同、平行和圆柱形孔组成的模型膜中 Onsager 唯象关系的一些系数 LU 的表达式。对吉布斯模型和经典空间电荷模型预测的均匀带电孔隙中的电导值和流动势值进行了比较。尽管模型固有的明显简化，但电导率具有良好的一致性，而流电势预测之间仅存在定性一致性。
The Gibbs model for the boundary between two phases consists of replacing the finite interfacial region, where the properties of the system change gradually, by a dividing surface which acts as a third phase of zero volume in which some magnitudes change abruptly. This thermodynamic concept was recently applied to a planar interface between a fixed charge membrane and an electrolyte solution.(1) The continuous decrease of counterions with the distance from the charged surface is replaced by a step function, so that the diffuse double layer is ideally represented by a charged region depleted of all co-ions. Here the cylindrical geometry is analyzed, and the planar case is revisited by proposing a slightly different step function for ion concentration. By starting from Boltzmann distributions of ions in solution, simple formulas are obtained for the distance between the charged interface and the dividing surface in both geometries. For the purpose of applying this model to charged, microporous membranes, expressions are given for some of the coefficients LU Of the Onsager phenomenological relations in a model membrane composed of identical, parallel, and cylindrical pores. A comparison is made between the Values for conductance and streaming potential in a homogeneously charged pore predicted by the Gibbs model and the classical space charge model. Despite the obvious simplifications inherent to the model, good agreement is found for conductivity, while only qualitative agreement is found between streaming potential predictions.