水分子在水化蒙脱石表面脱附行为的第一性原理研究

使用密度泛函理论计算研究了水分子在蒙脱石(MMT)表面的脱附作用.水分子在MMT表面的脱附受到配衡离子(Li~+,Na~+,或K~+),MMT表面和吸附水分子的共同作用.通过势能面扫描得到了脱附水分子在MMT表面脱附的能量路径.通过对脱附水分子能量路径的分析发现:水分子在MMT表面的脱附能垒受到配衡离子种类的影响,半径较小的配衡离子具有较大的脱附能垒.此外,吸附水的存在能降低脱附水分子的脱附能垒,使脱附过程容易触发.

First-principles study of water desorption on hydrated montmorillonite surface

The desorption of water on montmorillonite (MMT) sutface is investigated by means of density functional theory calculations. Desorption water interacted with counterion (Li+, Na+, or K+), MMT surface , and surrounding water absorbed on counterion. The energy path was obtained through potential energy surface (PES) scanning. Our calculations reveal that water desorption on MMT surface is greatly influenced by counterions, which with larger radii have greater energy barrier. Moreover, the existence of surrounded adsorption water reduces the energy barrier, makes water desorption on MMT surface much easier.