STRUCTURAL MODEL OF A113-PILLARED MONTMORILLONITE

Abstract--Alumina-pillared montmorillonite is prepared by intercalation of polyoxyhydroxy aluminum cations (Al~3 v+) of a natural montmorillonite from Dimitrovgrad, Bulgaria. Transmission electron micros-copy, powder X-ray diffraction, energy dispersive X-ray spectroscopy, and surface area (BET) methods are used to study the untreated and pillared forms of the monmlorillonite. A structural model involving deformed Al~3 pillars is proposed. Four pillar types are derived and these pillars are uniformly distributed over the interlayer-cation positions of montmorillonite. Calculated electron diffraction patterns were sim-ulated using the multi-slice method. The structural model explains the increased ordering along the c axis of the pillared form compared with the untreated montmorillonite. The model explains the structure of a pillared montmorillonite with different distributions of the pillars in the interlayer. The proposed model is consistent with the observed ata