Clays and Clay Minerals, Vol. 56, No. 3, 322–337, 2008.
Loading...
Authors
Decarreau, Alain
Petit, Sabine
Martin, Francois
Farges, Francois
Vieillard, Philippe
Joussein, Emmanuel
Issue Date
2008
Type
Article
Language
Keywords
Periodicals , Geology , Clay Synthesis , FTIR Spectroscopy , High-charge Nontronite , Mossbauer Spectroscopy , XAFS
Alternative Title
Hydrothermal Synthesis, Between 75 And 150ºc, Of High-charge, Ferric Nontronites.
Abstract
High-charge nontronites were synthesized at 75, 90, 100, 110, 125, and 150ºC from a silicoferrous starting gel with Si2FeNa2O6.nH2O composition. This gel was oxidized in contact with air and then hydrothermally treated, for a period of 4 weeks, under equilibrium water pressure. The synthesized nontronites were similar to each other, regardless of the synthesis temperature. Their structural formula, obtained from chemical analysis, X-ray diffraction (XRD), and Fourier transform infrared (FTIR), Mo¨ssbauer, and X-ray absorption fine structure spectroscopies is: (Si3.25Fe3+ 0.75)Fe2 3+O10(OH)2Na0.75. A strictly ferric end-member of the nontronite series was therefore synthesized for the first time. The uncommon chemistry of the synthesized nontronites, notably the high level of Fe-for-Si substitution, induced particular XRD, FTIR, and differential thermal analysis-thermogravimetric analysis data. The ethylene glycol expandability of the synthetic nontronites was linked to their crystallinity and depended on the nature of the interlayer cation, moving from smectite to vermiculite-like behavior. As the synthesis temperature increased, the crystallinity of the synthesized clays increased. The nontronite obtained at 150ºC had the ‘best crystallinity’, which cannot be improved by increasing synthesis time or temperature.
Description
Clays and Clay Minerals, Vol. 56, No. 3, 322–337, 2008. Hydrothermal Synthesis, Between 75 And 150ºc, Of High-charge, Ferric Nontronites. Alain Decarreau; Sabine Petit; Francois Martin; Francois Farges; Philippe Vieillard; Emmanuel Joussein. DOI: 10.1346/CCMN.2008.0560303.Copyright © 2008, The Clay Minerals Society.
Citation
Clays and Clay Minerals, Vol. 56, No. 3, 322–337, 2008.
Publisher
The Clay Minerals Society
License
Copyright © 2006-2018, The Clay Minerals Society