EFFECT OF DIELECTRIC SATURATION ON DISJOINING PRESSURE IN THIN-FILMS OF AQUEOUS-ELECTROLYTES
EFFECT OF DIELECTRIC SATURATION ON DISJOINING PRESSURE IN THIN-FILMS OF AQUEOUS-ELECTROLYTES
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DOI：
10.1006/jcis.1994.1241
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发表时间：
1994-07-01
影响因子：
9.9
通讯作者：
SHARMA, MM
中科院分区：
文献类型：
--
作者：
BASU, S;SHARMA, MM
提出了一种理论来量化两个电荷调节表面之间的水性电解质薄膜中的静电力。泊松-玻尔兹曼方程，由 Gur 等人修改。 (J. Colloid Interface Sci. 64, 326 (1978)) 包括离子水合自由能的影响，对重叠双层进行数值求解。结果表明，介电常数随着电场的增加而降低，双层离子的水合自由能增加，从而产生额外的排斥力。这些“水合”力与膜厚度呈指数或幂律关系，具体取决于双层中的介电饱和程度。所获得的结果与 Pashley (J. Colloid Interface Sci. 80, 153 (1981)) 在低电解质浓度和 pH 条件下的实验数据非常吻合。在较高的浓度和 pH 值下，该模型提供了与实验观察结果的定性一致性。结论是，高电荷界面附近双层的介电饱和可能在电解质薄膜的静电相互作用中发挥重要作用。 (C) 1994 年学术出版社
A theory is presented to quantify the electrostatic forces in thin aqueous electrolyte films between two charge regulating surfaces. The Poisson-Boltzmann equation, as modified by Gur et al. (J. Colloid Interface Sci. 64, 326 (1978)) to include the effects of hydration free energy of ions, is numerically solved for overlapping double layers. It is shown that the reduction in dielectric constant with increasing electric field increases the hydration free energy of the ions in the double layer, giving rise to an additional repulsive force. These ''hydration'' forces follow an exponential or a power-law relation with film thickness depending upon the degree of dielectric saturation in the double layer. The results obtained agree remarkably well with the experimental data of Pashley (J. Colloid Interface Sci. 80, 153 (1981)) at low electrolyte concentration and pH. At higher concentration and pH, the model provides qualitative agreement with experimental observations. It is concluded that dielectric saturation of the double layer near highly charged interfaces may play an important role in electrostatic interactions in thin electrolyte films. (C) 1994 Academic Press, Inc.