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Formation, compositions, and properties of hydroxy-A1- and hydroxy-Mg-montmorillonite

G. W. Brindley and Chih-Chun Kao
Formation, compositions, and properties of hydroxy-A1- and hydroxy-Mg-montmorillonite
Clays and Clay Minerals (December 1980) 28 (6): 435-443


Hydroxy-Al- and hydroxy-Mg-montmorillonite were prepared by treating dispersed Na-montmorillonite with aluminum and magnesium nitrate solutions and titrating with NaOH solutions so that the OH/Al ratio varied from zero to 3.0 and the OH/Mg ratio from zero to 2.0. External precipitation of Al and Mg hydroxides was observed when the OH/M ratios (M = metal) approached 3 and 2, respectively. From chemical analyses of the initial Na-montmorillonite and the hydroxy-metal montmorillonites, structural formulae were derived by assuming that the silicate layer compositions remained unchanged. Prior to the addition of NaOH, the average interlayer material approximated in composition to [Al(OH) (sub 2) ] (super +) and [Mg(OH)] (super +) . With additions of NaOH the interlayer compositions moved progressively towards Al(OH) (sub 3) and Mg(OH) (sub 2) . When the hydroxy interlayers approached completion, external precipitation was observed. X-ray powder diffraction data showed that the hydroxy-Mg products have less tendency to swell in ethylene glycol and water, and greater thermal stability than the hydroxy-Al products. Initially, when the average interlayer compositions were near Al(OH) (sub 2) and Mg(OH), swelling followed more nearly the normal behavior.

ISSN: 0009-8604
Serial Title: Clays and Clay Minerals
Serial Volume: 28
Serial Issue: 6
Title: Formation, compositions, and properties of hydroxy-A1- and hydroxy-Mg-montmorillonite
Affiliation: Pa. State Univ., University Park, PA, United States
Pages: 435-443
Published: 198012
Text Language: English
Summary Language: Russian
Summary Language: German
Summary Language: French
Publisher: Clay Minerals Society, Clarkson, NY, United States
References: 30
Accession Number: 1981-036148
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. tables
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
Update Code: 1981
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