Institute of Molecular Modeling and Simulation , University of Natural Resources and Life Sciences , Muthgasse 18 , 1190 Vienna , Austria.
Institute of Soil Research , University of Natural Resources and Life Sciences , Peter-Jordan-Straße 82 , 1190 Vienna , Austria.
Langmuir. 2019 Nov 26;35(47):15086-15099. doi: 10.1021/acs.langmuir.9b02945. Epub 2019 Nov 12.
Computational models of clay minerals and their interactions with the surrounding medium are highly valuable to study adsorption processes at an atomistic resolution, which may be relevant in different areas such as chromatography, environmental chemistry, and so forth. In this work, we analyzed the effect of the treatment of long-range interactions on the polarization of kaolinite-water interfacial systems in terms of structural, electric and dynamic properties, and hydrogen bonds. When using conventional three-dimensional (3D) Ewald summation, water molecules were more structured on the alumina interface of the kaolinite compared to simulations, in which the periodicity perpendicular to the plane was effectively removed. By applying an external electric field to the latter simulations, we were able to reproduce results obtained with the 3D Ewald summation. We proved that the induced polarization promotes adsorption processes of polar and charged species from aqueous solutions using a glyphosate molecule (widely used herbicide) as a particular example. The polarization phenomena raised from the simulation setup should be accounted for carefully in simulations of adsorption processes, which involve periodic images of polar interfaces. An inappropriate treatment of long-range electrostatic interactions can easily lead to artifacts and/or erroneous results.
粘土矿物及其与周围介质相互作用的计算模型对于在原子分辨率水平上研究吸附过程非常有价值，这些过程可能与色谱学、环境化学等不同领域相关。在这项工作中，我们分析了处理远程相互作用对高岭石-水界面系统极化的影响，包括结构、电性和动力学特性以及氢键。在使用传统的三维（3D）Ewald 求和时，与模拟中有效去除垂直于平面的周期性的情况相比，水分子在高岭石的氧化铝界面上更具结构。通过对后者的模拟施加外部电场，我们能够重现使用三维 Ewald 求和获得的结果。我们证明了诱导极化可以促进水溶液中极性和带电物质的吸附过程，以草甘膦分子（广泛使用的除草剂）为例。在涉及极性界面周期性图像的吸附过程模拟中，应该仔细考虑模拟设置中出现的极化现象。如果远程静电相互作用处理不当，很容易导致伪影和/或错误的结果。
