摘要
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。
Hydration swelling and the interlayer structure properties of Na-montmorillonite were modeled with the energy minimizing and molecular dynamics （MI）） module of Cerius^2. The results indicate that when water content in montmorillonite clay is increased from 0 to 300 mg/g. the layer spacing after equilibration increases with the water content, which is consistent with data from previous experiments. The MD simulation of Na-montmorillonite with one-, two-and three-layer H2O shows the inner-sphere complexes of Na^＋ have tetrahedral charge substitution sites in all hydrates, but outer sphere complexes haveoctahedral chargc suhstitution sites that are comparatively fixed only in one layer hydrate, whereas Na^＋ begins to diffuse towards another direction in two-and thre-layer hydrates. The results of calculated self-diffusion coefficients for all three hydrates indicate that water and cation mobilities in the interlayer remain lower than those observed in bulk solution, Radial distribution functions of Na-O, O-O and H-O analysis illustrate that the molecular structure of interlayer water is different from the bulk solution.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2005年第8期996-1001,共6页
Journal of The Chinese Ceramic Society
基金
国家自然科学基金(40002009
40372073)
山西省自然科学基金(981026)资助项目。
关键词
钠蒙脱石能量最小化
分子动力学
自扩散系数
径向分布函数
sodium-montmorillonite
energy minimizing
molecular dynamics
self-diffusion coefficiem
radial distribution function
