Pillared clay studies pillar sizes

The Fe-B nanocomposite was synthesized by the so-called pillaring technique using layered bentonite clay as the starting material. The detailed procedures were described in our previous study [4]. X-ray diffraction (XRD) analysis revealed that the Fe-B nanocomposite mainly consists of Fc203 (hematite) and Si02 (quartz). The bulk Fe concentration of the Fe-B nanocomposite measured by a JOEL X-ray Reflective Fluorescence spectrometer (Model JSX 3201Z) is 31.8%. The Fe surface atomic concentration of Fe-B nanocomposite determined by an X-ray photoelectron spectrometer (Model PHI5600) is 12.25 (at%). The BET specific surface area is 280 m /g. The particle size determined by a transmission electron microscope (JOEL 2010) is from 20 to 200 nm. 

The relatively small size of the pillars and the relatively low long-range ordering of intercalated clays exclude many surface and crystallographic techniques as suitable means of characterization. The present study is the first attempt to obtain interatomic distances in these systems from EXAFS data. Our results clearly show the utility of this method for local structural analysis of these clay materials. The interatomic distances obtained for chromia-pillared montmorillonite suggest similarities between the structure of the pillars and the structure of Cr203 (22). This result is in agreement... 

Nanoporous materials like zeolites and related materials, mesoporous molecular sieves, clays, pillared clays, the majority of silica, alumina, active carbons, titanium dioxides, magnesium oxides, carbon nanotubes and metal-organic frameworks are the most widely studied and applied adsorbents. In the case of crystalline and ordered nanoporous materials such as zeolites and related materials, and mesoporous molecular sieves, their categorization as nanoporous materials are not debated. However, in the case of amorphous porous materials, they possess bigger pores together with pores sized less than 100 nm. Nevertheless, in the majority of cases, the nanoporous component is the most important part of the porosity. 

The description that we have given of most of the anionic clays corresponds to PLS. The intercalates of other lamellar compounds (graphites, clays, phosphates, phosphonates, oxides, oxy-halides, and chalcogenides) have been intensively studied for their pillaring properties. The primary reason for this interest is the possibility of engineering the pore sizes and distribution during the pillaring process. 

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