Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia.
Langmuir. 2010 May 4;26(9):6430-6. doi: 10.1021/la9041265.
Surface potentials of alkali earth nitrates at a mica surface are calculated using a modified Poisson-Boltzmann approach that includes nonelectrostatic ion-surface dispersion interactions. New ab initio dynamic polarizabilities are used to determine dispersion interactions. A hydration model describing the hydration shell of cations is presented. Excellent agreement with experiment is achieved, including charge reversal at high electrolyte concentration without the need for site binding models. This suggests that specific ionic dispersion forces provide the mechanism for ion surface binding. An asymptotic surface potential is found in the limit of very high concentration. A Hofmeister series is predicted according to the strength of charge reversal, with Mg > Ca > Sr > Ba. The ion-surface dispersion adsorption energies of hydrated ions appear to explain the apparent repulsive secondary hydration forces observed experimentally between mica surfaces when taken with a surface hydration layer.
利用一种改进的泊松-玻尔兹曼方法，包括非静电离子-表面色散相互作用，计算了碱土硝酸盐在云母表面的表面电势。使用新的从头算动态极化率来确定色散相互作用。提出了一种描述阳离子水合壳的水合模型。实验结果吻合得非常好，包括在高电解质浓度下的电荷反转，而无需使用位绑定模型。这表明特定的离子色散力提供了离子表面结合的机制。在非常高的浓度极限下发现了渐近表面电势。根据电荷反转的强度预测了一个赫斯迈耶序列，其中 Mg > Ca > Sr > Ba。当与表面水合层一起考虑时，水合离子的离子-表面色散吸附能似乎可以解释实验中观察到的云母表面之间明显的二次水合排斥力。
