ABSTRACT To study the formation mechanism of hydration films, a lignite molecular model based on FTIR analysis was established. Both the positive and negative extreme values (±184.76 kJ/mol) of the electrostatic potential appear around oxygen-containing functional groups. Water molecules are mainly adsorbed near oxygen-containing functional groups. This paper studies the absorption of lignite for water molecules using MD simulation. With the addition of water molecules, the number of polar groups increases, and the electrostatic potential level of the system increases, causing an increase in the number of active sites. When the amount of water is inadequate for covering the surface of lignite, water molecules adsorb at active sites and places with lower z values. As the number of water molecules increase, the average length of hydrogen bonds between water molecules and that between lignite and water are close to the set values (1.97 and 1.8 Å, respectively). The short-range order structure of the interface has little effect on the average bond length of water molecules, but it reduces the average bond angle by 1°~2°. After a hydration film forms, the increase to the thickness of the hydration film is primarily attributed to hydrogen-bond interaction between water molecules.

中文翻译：

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褐煤结构简化模型吸水分子动力学模拟

摘要 为研究水化膜的形成机理，建立了基于红外光谱分析的褐煤分子模型。静电势的正负极值 (±184.76 kJ/mol) 均出现在含氧官能团周围。水分子主要吸附在含氧官能团附近。本文使用MD模拟研究了褐煤对水分子的吸收。随着水分子的加入，极性基团的数量增加，系统的静电势能级增加，导致活性位点的数量增加。当水量不足以覆盖褐煤表面时，水分子会吸附在活性位点和 z 值较低的地方。随着水分子数量的增加，水分子之间和褐煤与水之间的氢键平均长度接近设定值（分别为 1.97 和 1.8 Å）。界面的短程有序结构对水分子的平均键长影响不大，但使平均键角降低了1°~2°。水化膜形成后，水化膜厚度的增加主要归因于水分子之间的氢键相互作用。