Lattice site exclusion effect on the double layer interaction
Lattice site exclusion effect on the double layer interaction
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DOI：
10.1021/la020194r
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发表时间：
2002-06-25
期刊：
影响因子：
3.9
通讯作者：
Ruckenstein, E
中科院分区：
文献类型：
--
作者：
Manciu, M;Ruckenstein, E
提出了电解质溶液的晶格模型，该模型假设水合离子占据水晶格上的tau(i) （i = 1,2）个位点。离子“i”只有在它是“自由的”（它被水分子占据，而水分子不与离子水合）并且至少有（tau(i) - 1）个第一邻居是自由的情况下，晶格位点才能被离子“i”利用。该模型考虑了相邻位置占用概率之间的相关性，并用于计算双层相互作用的“排除体积”（晶格位置排除）效应。结果表明，与泊松-玻尔兹曼处理预测的厚度相比，在高表面电位下，在带电表面附近产生的双层厚度增加。然而，在低表面电位下，如果水合共离子大于水合反离子，则弥散双离子层可以被轻微压缩。离子的有限尺寸可以导致双层斥力的增加或甚至小幅度的减少。这种效应在很大程度上取决于两种离子的水化数。
A lattice model for an electrolyte solution is proposed, which assumes that the hydrated ion occupies tau(i) (i = 1, 2) sites on a water lattice. A lattice site is available to an ion "i" only if it is "free" (it is occupied by a water molecule, which does not hydrate an ion) and has also at least (tau(i) - 1) first-neighbors free. The model accounts for the correlations between the probabilities of occupancy of adjacent sites and is used to calculate the "excluded volume" (lattice site exclusion) effect on the double layer interactions. It is shown that at high surface potentials the thickness of the double layer generated near a charged surface is increased, when compared to that predicted by the Poisson-Boltzmann treatment. However, at low surface potentials, the diffuse double layer can be slightly compressed, if the hydrated co-ions are larger than the hydrated counterions. The finite sizes of the ions can lead to either an increase or even a small decrease of the double layer repulsion. The effect can be strongly dependent on the hydration numbers of the two species of ions.