A simple statistical mechanical approach to the free energy of the electric double layer including the excluded volume effect
A simple statistical mechanical approach to the free energy of the electric double layer including the excluded volume effect
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DOI：
10.1051/jp2:1996193
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发表时间：
1996-04-01
期刊：
影响因子：
--
通讯作者：
Iglic, A
中科院分区：
文献类型：
--
作者：
KraljIglic, V;Iglic, A
应用简单的分析统计力学方法来推导单个双电层的自由能表达式。通过平均静电场来考虑静电相互作用，而通过排除体积效应来考虑构成电解质溶液的颗粒的有限尺寸。将计算出的一价电解质的自由能与通过泊松-玻尔兹曼理论获得的相应自由能进行比较。结果表明，排除的体积效应显着增加了静电场的能量，而熵贡献的相应降低则不太明显。由于熵的贡献大于静电场的能量，并且对两种贡献的影响部分抵消，因此泊松-玻尔兹曼理论获得的自由能对于排除体积效应是一个很好的近似。
A simple analytic statistical mechanical approach is applied to derive an expression for the free energy of a single electric double layer. Electrostatic interactions are considered by means of the mean electrostatic field while the finite size of particles constituting the electrolyte solution is considered by including the excluded volume effect. The calculated free energy of an univalent electrolyte is compared to the corresponding free energy obtained by the Poisson-Boltzmann theory. It is shown that the excluded volume effect considerably increases the energy of the electrostatic field while the corresponding decrease of the entropic contribution is less pronounced. As the entropic contribution is larger than the energy of the electrostatic field and as the effects on both contributions partially cancel, the free energy obtained by the Poisson-Boltzmann theory is an excellent approximation regarding to the excluded volume effect.