Internal Surface of Clays and Constrained Chemical Reactions

Fripiat, J. J.

doi:10.1346/ccmn.1986.0340501

Cited by 27 publications

(12 citation statements)

References 24 publications

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“…Pillared layered clays (PILCs) constitute a novel class of microporous materials with a thermal stability up to about 700~ a surface area in the range of 200 to 500 m2/g and a pronounced Bronsted and Lewis acidity (Brindley and Sempels, 1977;Pinnavaia, 1983;Fripiat, 1986;Bergaya and Barrault, 1990). These materials result from a two-step modification of naturally occurring or synthetic swelling clay minerals, i.e., smecrites.…”

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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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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“…Phyllosilicate organic reactions have been extensively investigated generating information on different types of interactive mechanisms, such as the multivariable reactions involving silicate layers, inorganic cations, water, and organic molecules [18]. Therefore, many experimental routes have been proposed to explore solid/solid [19] and solid/liquid [20] interface reactions.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of modified vermiculite by interaction with aromatic heterocyclic amines

Fonseca

Cardoso

Wanderley

et al. 2006

Journal of Physics and Chemistry of Solids

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“…The different types of interaction have been classified as sorption, ion exchange and intercalation. These interactions may take place on both external and internal surfaces, or may be restricted to the external surface (Barshad 1952;Raman and Mortland 1969;Stutzmann and Siffert 1977;Lagaly and Witter 1982;Fripiat 1986;Lagaly 1987;Ruiz-Amil et al 1992). The present work is a contribution to the study of the interaction of organic molecules with layer silicates, in particular using vermiculite.…”

Section: Introductionmentioning

confidence: 99%

Interaction of Vermiculite with Aliphatic Amides (Formamide, Acetamide and Propionamide): Formation and Study of Interstratified Phases in the Transformation of Mg- to NH₄-Vermiculite

Ruíz-Conde

1997

Clays and clay miner.

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Abstract--The Mg-vermiculite from Santa Olalla has been treated with aliphatic amides--formamide (FM), acetamide (AM) and propionamide (PM)--in aqueous solution. These treatments produce the transformation towards NH4-vermiculite and interstratified NH:vermiculite-Mg-vermiculite phases. The NH 4-vermiculite, Mg-vermiculite and interstratified (mixed-layer)~phases have been identifed from basal X-ray diffraction (XRD) interval peaks between 10,3 _~ and 14,4 A, and confirmed by direct Fourier transform method, as well as by atomic absorption spectrometry (AAS), infrared (IR) spectroscopy and thermal analysis.According to their NH:vermiculite/Mg-vermiculite probability coefficients ratio (Pa/PB), and PAA, these interstratified phases can be divided into 3 categories: 1) If the Pa/Pn ratio is --> 7/3 and PAA ~" 0,7, there are interstratified phases with a strong tendency toward segregation (case of FM, AM and PM). Experimental evidence reported in the present work indicates that the mechanism of interaction of Mg-vermiculite with FM, AM and PM in an aqueous medium takes place by ion exchange of NH 4 between the layers. The hydrolysis of these aliphatic amides leads to the liberation of NHa + into the medium. It has been found that the NH4 § sorption depends on the physico-chemical characteristics of the particular aliphatic amide, and the transformation of Mg-vermiculite to interstratified and/or NH4-vermiculite phases depends on the amide concentration. These treatments allow one to control the formation of interstratified and NH4-vermiculite phases.

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Internal Surface of Clays and Constrained Chemical Reactions

Cited by 27 publications

References 24 publications

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

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

Synthesis of modified vermiculite by interaction with aromatic heterocyclic amines

Interaction of Vermiculite with Aliphatic Amides (Formamide, Acetamide and Propionamide): Formation and Study of Interstratified Phases in the Transformation of Mg- to NH₄-Vermiculite

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Internal Surface of Clays and Constrained Chemical Reactions

Cited by 27 publications

References 24 publications

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

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

Synthesis of modified vermiculite by interaction with aromatic heterocyclic amines

Interaction of Vermiculite with Aliphatic Amides (Formamide, Acetamide and Propionamide): Formation and Study of Interstratified Phases in the Transformation of Mg- to NH4-Vermiculite

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Interaction of Vermiculite with Aliphatic Amides (Formamide, Acetamide and Propionamide): Formation and Study of Interstratified Phases in the Transformation of Mg- to NH₄-Vermiculite