State Key Laboratory of Oil and Gas Reservoir Geology and Exploration, School of Petroleum Engineering, Southwest Petroleum University, Chengdu 610500, China.
J Mol Model. 2013 Apr;19(4):1875-81. doi: 10.1007/s00894-012-1748-x. Epub 2013 Jan 17.
Density functional theory calculations were performed to investigate the adsorption and hydration of an ammonium ion (NH4(+)) confined in the interlayer space of montmorillonites (MMT). NH4(+) is trapped in the six-oxygen-ring on the internal surface and forms a strong binding with the surface O atoms. The hydration of NH4(+) is affected significantly by the surface. Water molecules prefer the surface sites, and do not bind with the NH4(+) unless enough water molecules are supplied. Moreover, the water molecules involved in NH4(+) hydration tend to bind with the surface simultaneously. The hydration energy increases with the intercalated water molecules, in contrast to that in gas phase. In addition, the hydration leads to the extension of MMT basal spacing.
采用密度泛函理论计算研究了铵离子（NH4(+））在蒙脱石夹层空间中的吸附和水合作用。NH4(+)被捕获在内部表面的六氧环上，并与表面 O 原子形成强结合。表面对 NH4(+)的水合作用有显著影响。水分子优先占据表面位，除非提供足够多的水分子，否则不会与 NH4(+)结合。此外，参与 NH4(+)水合作用的水分子往往同时与表面结合。与气相相比，水合能随嵌入水分子的增加而增加。此外，水合作用导致蒙脱石层间距的扩展。
