Characterisation of pillared clays by neutron scattering

Pinnavaia, T. J.; Rainey, V.; Tzou, Ming-Shin; White, John W.

doi:10.1016/0304-5102(84)85081-6

Cited by 25 publications

(12 citation statements)

References 10 publications

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“…In the interlamellar space, the average surface area ,,A17 ,, ion is 9.8 nm 2 which is seven times that of Na +. If the average occupied by the ,,,13 interpillar distance taken from edge to edge is about 2-5 nm (Pinnavaia et al, 1984), the calculated "AI~" ion radius is 0.51 nm which is approximately the radius in the crystal state (0.55 nm) (Johansson et al, 1960), or 0.4 nm from the results reported by Pinnavaia et al (1984). In solution, the average spherical radius of the hydrated "^17+"rxlx3 ion is 1-26 nm (Bottero et al, 1982a).…”

Section: Discussionsupporting

confidence: 47%

“…The specific surface area of Al-clay can be 10 times that of pure Na-or Ca-montmorillonite and then the solid becomes a molecular sieve which has been studied for its catalytic properties Lahav & Shani, 1978;Occelli & Tindwa, 1983;Pinnavaia et al, 1984;Plee et al, 1985), and agricultural applications (Rengasamy & Oades, 1978;Oades, 1984). Often the interaction mechanisms at the molecular scale have not been described well because the nature of the AI species was not correctly known.…”

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confidence: 99%

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Interactions between hydroxy-aluminium species and homoionic Na- and Ca-montmorillonite particles, as manifested by ζ potential, suspension stability and X-ray diffraction

1988

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: The interactions between AllaO4(OH)24(H20)~ ~ and higher molecular weight hydroxy-Al species with homoionic Na-and Ca-montmorillonite have been studied by measuring adsorption of the hydroxy-Al on to the clay, turbidity of the resulting suspensions, electrokinetic potential, and d(001) basal spacing. The isolated "Alia" ions are adsorbed according to a cation-exchange process which causes flocculation of the tactoids at low concentrations. At higher concentrations, the adsorption of either isolated "All3" or/and higher molecular weight species is mainly responsible for the dispersion of clay particles with a net positive surface charge (~ ~ + 50 mV). Consequently, the tactoids are destroyed.

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Section: Discussionsupporting

confidence: 47%

mentioning

confidence: 99%

Interactions between hydroxy-aluminium species and homoionic Na- and Ca-montmorillonite particles, as manifested by ζ potential, suspension stability and X-ray diffraction

1988

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“…(Vaughan and Lussier, 1980;Occelli, 1983;Bergaya et al, 1991) has stimulated research not only for the synthesis of new PILCs, but also for their extensive microscopic characterization. A wide spectrum of analytical techniques, e.g., magic-angle spinning NMR (Plee et al, 1985;Tillak et aL, 1986), EPR (Harsh and Doner, 1984;Braddell et aL, 1987), neutron scattering (Pinnavaia et al, 1984), NMR and HzTPR (Bergaya et al, 1993) and M6ssbauer spectroscopy (Gangas et aL, 1985;Lee Woo et al, 1989;Petridis et al, 1989), has been used for unravelling the structure and the properties of these novel materials. However, in spite of the substantial advance made up to now in the synthesis and characterization of PILCs, the elucidation of additional aspects of the pillared structure (e.g., the diameter of the pillars) is of cardinal importance for understanding the role of their morphology in physicochemical processes occurring in the interlayer space, as well as developing applications,…”

Section: Introductionmentioning

confidence: 99%

Redox Treatment of an Fe/Al Pillared Montmorillonite. A Mössbauer Study

Bakas

Moukarika

Papaefthymiou

et al. 1994

Clays and clay miner.

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Abstract--Pillared structures with an interlayer opening of ~ 0.3 nm were obtained after successive heat treatments of the PILC precursor in reducing and oxidizing conditions. This precursor was prepared by reacting a Na+-montmorillonite with an intercalant containing A1 and Fe oxo-hydroxides (A1/Fe = 1). Powder X-ray diffraction, elemental analysis, 57Fe Mrssbauer spectroscopy, catalytic activity measurements and surface area data were used to characterize the samples. On the basis of M6ssbauer spectra taken at temperatures between 4.2 and 300 K, it is deduced that oxidizing steps produce A1 substituted maghemite which converts into A1 substituted magnetite upon reducing heat treatment. Firing the precursor in oxidizing atmosphere forms pillars of few nm in diameter. However, heating under reducing conditions yields pillars of smaller diameter. This later behaviour is maintained even after reheating the material in oxidizing atmosphere. From the temperature dependence of M6ssbauer spectra it is deduced that the diameter of the Fe oxide particles in the pillars is smaller than 10 nm.

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“…Montmorillonite (Mt), as a naturally occurring micro-and mesoporous material, is an ideal host for synthesizing heterostructures in terms of its unique combination of cation exchange, intercalation, and swelling properties (Pinnavaia, 1983). In the dry state, a Mt system can be described by three structural units and by the arrangement of these units in space (Neaman et al, 2003;.…”

Section: Introductionmentioning

confidence: 99%

“…This technique accurately determines the amount of nitrogen adsorbed on a solid material, and the isotherm obtained from adsorption measurements, combined with various computational models, can offer information on textural characteristics. Other techniques including 129 xenonnuclear magnetic resonance (Tsiao et al, 1998), transmission electron microscopy (TEM) (Groen et al, 2003), atomic force microscopy (AFM) (Occelli et al, 1994), X-ray diffraction (XRD) (He et al, 2006), and small-angle neutron scattering (Pinnavaia et al, 1984a) are also often used to complement the adsorption results and provide a more detailed picture of the porous and structural aspects of the materials under investigation.…”

Section: Introductionmentioning

confidence: 99%

A Critical Textural Evolution Study of Zerovalent Iron/Montmorillonite Nanosized Heterostructures Under Various Iron Loadings

Fan

Yuan

Bergaya

et al. 2011

Clays and clay miner.

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Abstract-Heterostructures formed by nanoparticles hybridized with porous hosts are of great potential in many practical applications such as catalysis, adsorption, and environmental remediation, based on their intrinsic properties. The objectives of this study were to synthesize zerovalent iron nanoparticles/ montmorillonite heterostructures and to investigate their textural evolution under different Fe loadings. Iron nanoparticles were hybridized with montmorillonite by impregnation of montmorillonite by ferric ions followed by chemical reduction with sodium borohydride in solution. These hybridized Fe nanoparticles were well dispersed on the montmorillonite surface, size adjustable, and resistant to oxidation under the protection of native Fe-oxide shells. The textural evolution of these heterostructures under various Fe loadings was investigated using nitrogen physisorption, X-ray diffraction, electron microscopy, and elemental analyses. As the Fe loadings increased, the total pore and mesopore volumes were almost unchanged; the total, micropore, and external surface areas as well as the micropore volume decreased; and the average pore diameter increased. These textural changes could be attributed to the filling of the interparticle pores of montmorillonite by a variable amount of Fe nanoparticles. In addition, with increasing Fe loadings, the mesoporous character was enhanced for these heterostructures. These fundamental results are important in understanding the structure of these heterostructures as well as in developing some novel applications in related fields.

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Characterisation of pillared clays by neutron scattering

Cited by 25 publications

References 10 publications

Interactions between hydroxy-aluminium species and homoionic Na- and Ca-montmorillonite particles, as manifested by ζ potential, suspension stability and X-ray diffraction

Interactions between hydroxy-aluminium species and homoionic Na- and Ca-montmorillonite particles, as manifested by ζ potential, suspension stability and X-ray diffraction

Redox Treatment of an Fe/Al Pillared Montmorillonite. A Mössbauer Study

A Critical Textural Evolution Study of Zerovalent Iron/Montmorillonite Nanosized Heterostructures Under Various Iron Loadings

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