Adsorption of large ions from an electrolyte solution: a modified Poisson-Boltzmann equation
Adsorption of large ions from an electrolyte solution: a modified Poisson-Boltzmann equation
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DOI：
10.1016/s0013-4686(00)00576-4
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发表时间：
2000-11-01
影响因子：
6.6
通讯作者：
Orland, H
中科院分区：
文献类型：
--
作者：
Borukhov, I;Andelman, D;Orland, H
从理论上研究了电解质溶液靠近带电表面的行为。提出了一个修正的泊松-玻尔兹曼方程，该方程除考虑静电相互作用外，还考虑了离子所排除的体积。在晶格气体形式中，修正泊松-玻尔兹曼方程可以由配分函数的平均场近似得到。在另一种现象学方法中，通过将溶剂分子的熵包括在自由能中，可以推导出相同的方程。为了可视化空间斥力的影响，我们讨论了一个简单的单，高电荷，平面的例子。这种情况类似于最近的大离子在带电单层上的吸附实验。空间效应重要性的一个简单标准是用表面电荷密度和离子的大小来表示的。结果表明，当这些影响很重要时，在地表附近会形成一个饱和层。得到了表面离子浓度与表面电荷密度的关系式。(C) 2000 Elsevier Science Ltd.版权所有。
The behavior of electrolyte solutions close to a charged surface is studied theoretically. A modified Poisson-Boltzmann equation that takes into account the volume excluded by the ions in addition to the electrostatic interactions is presented. In a formal lattice gas formalism the modified Poisson-Boltzmann equation can be obtained from a mean-field approximation of the partition function. In an alternative phenomenological approach, the same equation can be derived by including the entropy of the solvent molecules in the free energy. In order to visualize the effect of steric repulsion, a simple case of a single, highly charged, flat surface is discussed. This situation resembles recent adsorption experiments of large ions onto a charged monolayer. A simple criterion for the importance of the steric effects is expressed in terms of the surface charge density and the size of the ions. It is shown that when these effects are important a saturated layer is formed near the surface. A modified Grahame equation relating the ion concentration at the surface to the surface charge density is obtained. (C) 2000 Elsevier Science Ltd. All rights reserved.