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运用Cerius2软件中能量最小化和分子动力(moleculardynamics,MD)模块研究了钠蒙脱石的水化膨胀性能和层间结构特征。计算结果表明:当蒙脱石粘土中的水含量从0增加到300mg/g时,平衡时蒙脱石的层间距d001值也随之增大,并且和实验数据吻合良好。通过对含有一、二、三层水分子钠蒙脱石的MD模拟可以看出,Na+在所有水化物中和四面体电荷位置成内层配位作用,而和八面体电荷位置成外层配位作用的Na+只在一层水化物中位置比较固定,在二层和三层水化物中逐渐向层中其它方向扩散。对所有3种水合物自扩散系数的计算结果说明:层间阳离子和水分子的活动性比水溶液中的低。Na-O,O-O和H-O的径向分布函数分析表明层间水分子的结构和水中水分子的结构不同。
The hydration swelling behavior and interlayer structure of sodium montmorillonite were studied using the energy minimization and molecular dynamics (MD) module of Cerius2 software. The calculated results show that when the water content in montmorillonite clay increases from 0 to 300 mg / g, the d001 value of montmorillonite interlayer spacing increases at equilibrium, and it is in good agreement with the experimental data. It can be seen from the MD simulation of one, two and three water molecules Na-montmorillonite that Na + neutralizes tetrahedral charge sites in all hydrates and forms an inner coordination layer with the octahedral charge sites in the outer layer The role of the role of Na + only in a layer of hydrates in the relatively fixed position, in the two and three layers of hydration gradually spread to other layers. Calculations of the self-diffusion coefficients for all three hydrates show that interlayer cations and water molecules are less active than aqueous solutions. The radial distribution function analysis of Na-O, O-O and H-O shows that the structure of water molecules in water layer is different from that of water molecules in water.