部份层无序铝交联蒙脱土结构的研究

STRUCTURAL STUDY ON PARTIALLY DISORDERED LAYER LATTICE OF POLYOXYALUMINUM PILLARED MONTMORILLONITE

应用非完整晶体的XRD 衍射及阳离子交换量的测定等实验数据,得出了铝交联蒙脱土的三维结构模型.结构中Al(Ⅱ)多数以十三聚体形式进入层间,层间距为19.7(?),几率为0.65,少数以六聚体形式进入层间,层间距为15(?),几率为0.25,其余10%的层间仅为水分子.并给出了交联柱子在层间的分布与层单元之间的连接方式.目前通用的以Bragg 公式计算所得的d_(0001)值来表征交联浆脱土的层间距是不确切的.

The structure of pillared montmorillonite is partially disordered layer lattice.Its basal spacings can be expanded to many possible values with different probabili-ties depending on the type and structure of the pillars or the preparation conditions.If a formula describing the X-ray diffraction intensity of partially disordered layerlattice as a function of basal spacings and corresponding probabilities is computa-tionally simulated with the experimental XRD pattern,the basal spacings and prob-abilities can thus be obtained.In this work,two of the polyoxyaluminum pillaredmontmorillonite samples with Al_(13) as main pillars were prepared.The simulatedresults show that most of the basal spacings are expanded to 19.7(?) with a probabi-lity of 0.65 corresponding to Al_(13) as pillars;some of the basal spacings are 15(?)with a probability of 0.25 corresponding to Al_6 as the most possible pillaringspecies;the rest ones are 11(?) containing water molecules only in the interlamellarregion.The experimental results obtained from CEC,ICP etc.are used to calculatethe distribution of the pillars in the interlayer zone.Subsequently,a three-dimen-sional structural model is built up.The agreement of the pore-volume betweentheoretical calculation and experimental result verifies the rationality of the structuralmodel.Therefore,the basal spacing usually characterized by d_(001) which is calculatedfrom Bragg equation actually is not exact.