ζ-Potential (ZP) is among key physical properties characterizing the behavior of nanoparticles in colloidal solutions. Despite many attempts to calculate and neatly interpret the ZP, a full understanding of various factors influencing its values has not been achieved yet, even for standard metal oxides, particularly when considering high ionic concentrations and the effect of temperature. This contribution extends our recent work [Předota, M. Langmuir 2016, 32, 10189−10198], where we suggested a direct approach to calculate the ZP from nonequilibrium molecular dynamics (NEMD) simulations. Here, we investigate NaCl, RbCl, CaCl₂, SrCl₂, and Na₂C₂O₄ aqueous solutions interacting with TiO₂ and SiO₂ surfaces and show contrasting ZP behaviors of these metal oxides, elucidated by theoretical insights gained by molecular simulations. We show that both surface-specific and ion-specific properties play a key role in the observed electrokinetics. Additionally, we explore the concentration and temperature influence on the ZP of selected systems and discuss the measurement of the ZP of systems with surfaces and ions modeled using scaled partial charges. Our results agree well with available experimental data and capture all key ZP features predicted by theory or revealed by experiments and advance the microscopic description of solid/liquid interfaces, promoting further applications of the suggested NEMD approach.

中文翻译：

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通过分子模拟确定Zeta电位

ζ电位（ZP）是表征纳米粒子在胶体溶液中行为的关键物理特性之一。尽管进行了许多计算和巧妙地解释ZP的尝试，但对于标准ZP氧化物，尤其是在考虑高离子浓度和温度影响时，甚至尚未完全了解影响ZP值的各种因素。这项贡献扩展了我们最近的工作[M.Předota 朗缪尔 2016， 32，10189-10198]，其中我们提出了一个直接的方法来计算从非平衡分子动力学（NEMD）模拟的ZP。在这里，我们研究与TiO ₂和SiO ₂相互作用的NaCl，RbCl，CaCl ₂，SrCl ₂和Na ₂ C ₂ O ₄水溶液。表面，并显示出这些金属氧化物的ZP行为对比，分子模拟获得的理论见解阐明了这一点。我们表明，表面特异性和离子特异性都在观察到的动力学中起着关键作用。此外，我们探讨了浓度和温度对所选系统ZP的影响，并讨论了使用比例缩放的局部电荷模拟表面和离子的系统ZP的测量。我们的结果与可用的实验数据非常吻合，并捕获了理论预测或实验揭示的所有关键ZP功能，并推进了固/液界面的微观描述，从而促进了建议的NEMD方法的进一步应用。