Pillaring Processes of Smectites with and Without Tetrahedral Substitution

Plee, D.; Gatineau, L.; Fripiat, J. J.

doi:10.1346/ccmn.1987.0350201

Cited by 138 publications

(76 citation statements)

References 11 publications

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“…Farmer et al (1991aFarmer et al ( , 1991b found that saponite-and nontronite-like structures developed from aluminosilicate precipitates digested at 20~176 in solutions containing Mg and Fe ions, respectively. On the other hand, beidellite has been synthesized from aluminosilicate gel in NaOH solutions at 300~176 (Plee et al, 1987;Schutz et al, 1987). Kloprogge et al (1990) carried out hydrothermal synthesis of beidellite from aluminosilicate gel in NaOH solutions with a pH range from 7.5 to 13.5 at a temperature of 350~ They reported that the most highly crystallized beidellite was obtained at 350~ 1 kbar, 5 days of reaction, and a pH of 10 in the starting solution.…”

Section: Introductionmentioning

confidence: 99%

Formation of Allophane and Beidellite during Hydrothermal Alteration of Volcanic Glass Below 200°C

Kawano

Tomita

1992

Clays and clay miner.

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Abstract--Experimental alteration of volcanic glass has been carried out in distilled water at 200~ and 150~ The formation and transformation processes ofalterution products have been examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), infrared absorption analysis, and X-ray photoelectron spectroscopy. SEM and TEM clearly show that amorphous aluminum-silicate coatings with allophane particles precipitate on the surface of volcanic glass during the earliest alteration stage. Noncrystalline flaky and/or fibrous materials are formed from the allophane aggregates and from the amorphous coatings as new reaction products. The flaky and/or fibrous materials curl inward and transform into 100-500 nm circular smectite. The A1/Si atomic ratio of 1.09 for allophane decreases progressively to 0.65 for smectite through 0.86 for noncrystalline transitional material. The smectite has d(06) spacing of 1.497 /~ and consists mainly of Si, A1, and small amounts of Fe, Ca, and Na.

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Section: Introductionmentioning

confidence: 99%

Formation of Allophane and Beidellite during Hydrothermal Alteration of Volcanic Glass Below 200°C

Kawano

Tomita

1992

Clays and clay miner.

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“…However, the disadvantage of organic pillars is the low thermostability and the resulting collapse of the pillared clay structure. The use of inorganic compounds, such as A1 (Brindley & Sempels, 1977;Lahav et al, 1978;Plee et al, 1987;Schutz et al, 1987), and Zr (Vaughan et al, 1979; * Present address: TNO-TPD-TU Delft, Dept. of Inorganic Materials Chemistry, PO Box 595, 5600 AN Eindhoyen, The Netherlands.…”

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The Effect of Thermal Treatment on the Properties of Hydroxy-Al and Hydroxy-Ga Pillared Montmorillonite and Beidellite

et al. 1994

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A B S T R A C T :The pillaring process of montmorillonite and beidellite with A1 and Ga polymers has been studied using XRD, IR, 27A1, 71Ga, and 29Si MAS NMR, TGA, TEM, N2 adsorption and chemical analyses.The A1 adsorption maximum for montmorillonite is close to 5.5 mEq A1/g clay, whereas the maximum for Ga is higher. Basal spacings of both Ga-and Al-pillared clays vary between 16.7 and 18.8 ~,. Freeze-drying of pillared products followed by calcination yielded more regular pillared structures. Pillaring montmorillonite increased the BET surface area from 35 m2/g to 350 m2/g mainly by the creation of micropores <20 • in diameter. The Al-pillared clays are thermally stable to ~700~ Calcination of pillared montmorillonite liberates protons from the pillar, which diffuse into the clay sheet, lowering the thermal stability. In pillared beidellite, mainly silanol groups are formed by breaking Si-O-AI bonds. No reaction is observed between pillars and montmorillonite upon calcination, whereas in pillared beidellite a structural transformation links the pillar to inverted tetrahedra of the tetrahedral sheet. The basal spacing of Ga-pillared montmorillonite collapses to 9.5/~ at 350~ due to the Ga polymer decomposing to Ga 3+ cations.

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“…The best understood pillared clays (PILCs) are those in which Al oxide pillars act as molecular-sized props permanently separating the silicate layers of the clay, and the structure of these materials has been investigated using 27A1 and 29Si solid state MAS NMR (Tennakoon et al, 1986;Plee et al, 1985Plee et al, , 1987. If, however, the pillars are formed of Fe oxide instead of A1 oxide, interesting and novel magnetic properties may be expected (Gangas et al, 1985) and M6ssbauer spectroscopy can be utilized to obtain structural information.…”

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Preparation and characterization of iron oxide pillared montmorillonite

et al. 1988

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A B S T RA C T : Pillared smectites in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties. Several possible routes by which such materials might be made have been investigated, namely intercalation of hydroxy-Fe(III) polycations, mixed hydroxy-Fe(III)/Al polycations, phenanthroline-Fe(II) cations, and trinuclear Fe(III) acetato cations into Na-montmorillonite. Only the last of these yielded a pillared clay (PILC) on calcination. The products have been characterized using X-ray powder diffraction and 57Fe M6ssbauer spectroscopy. The precursor Fe-PILC has a d-spacing of 21 A and expands to 23 A on solvation with glycol. The calcined Fe-PILC has a d-spacing of 19 A (gallery height 9.4 A) and does not expand with glycol, confirming cross-linking of the layers. From M6ssbauer spectra at 4.2 K it is estimated that there are of the order of some hundred Fe atoms per pillar.Pillared or cross-linked smectites, in which the interlayer is converted into a two dimensional zeolite-like structure, have recently attracted much interest because of their catalytic and molecular sieving properties (Pinnavaia, 1983;Barrer, 1986). The best understood pillared clays (PILCs) are those in which Al oxide pillars act as molecular-sized props permanently separating the silicate layers of the clay, and the structure of these materials has been investigated using 27A1 and 29Si solid state MAS NMR (Tennakoon et al., 1986;Plee et al., 1985Plee et al., , 1987. If, however, the pillars are formed of Fe oxide instead of A1 oxide, interesting and novel magnetic properties may be expected (Gangas et al., 1985) and M6ssbauer spectroscopy can be utilized to obtain structural information.Metal oxide pillared clays are normally the product of a two step process. The first step is one of cation exchange in which the simple interlayer cation of a smectite (usually Na +) is replaced by a large complex cation. The second step consists of a heat treatment which crosslinks the silicate layers. In this paper, the terms precursor-PILC and calcined-PILC are used in order to make a clear distinction between the products obtained after each step.The complex cation which is used in the preparation of A1-PILCs is the Keggin-like ion [AllaO4(OH)24(H20)12] 7+ (Baes & Mesmer, 1976). In this study we have investigated the PILC-forming potential of a number of large Fe cations which can occupy the exchange sites in smectite interlayers. These are hydroxy-Fe(III) polycations, mixed hydroxy-Fe(III)/Al cations, phenanthroline-Fe(II) complexes and trinuclear Fe(III) carboxylate complexes. CHARACTERISTICS OF METAL OXIDE PILLARED CLAYSIntercalation of complex cations into a smectite followed by heat treatment may, or may not, result in the formation of a PILC. The following three criteria have been used to identify 9 1988 The Mineralogical Society

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Pillaring Processes of Smectites with and Without Tetrahedral Substitution

Cited by 138 publications

References 11 publications

Formation of Allophane and Beidellite during Hydrothermal Alteration of Volcanic Glass Below 200°C

Formation of Allophane and Beidellite during Hydrothermal Alteration of Volcanic Glass Below 200°C

The Effect of Thermal Treatment on the Properties of Hydroxy-Al and Hydroxy-Ga Pillared Montmorillonite and Beidellite

Preparation and characterization of iron oxide pillared montmorillonite

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