Clays and Clay Minerals, Vol. 57, No. 2, 139–149, 2009
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Authors
Fischer, Hakon
Weidler, Peter G.
Grobety, Bernard
Luster, Jorg
Gehring, Andreas U.
Issue Date
2009
Type
Article
Language
Keywords
Periodicals , Geology , Cu(II) , DSC , EPR , Hectorite , Hydrothermal Treatment , TG , XRD
Alternative Title
The Transformation Of Synthetic Hectorite In The Presence Of Cu(ii)
Abstract
The influence of Cu(II) on the hydrothermal and thermal transformations of a synthetic hectorite was investigated by a combined approach using mainly X-ray diffraction, thermal analyses, and electron paramagnetic resonance spectroscopy. The presence of Cu(II) during hydrothermal treatment increased the crystallite size. Copper (II) was both structure-bound and associated with the inner surfaces of the particles. Upon heating, structural destabilization of the hectorite began at ~400ºC as indicated by the formation of free radicals. Between 600 and 700ºC, the hectorite converted to enstatite, and in the presence of Cu(II), to enstatite and richterite. The formation of richterite as an additional conversion product is explained by the creation of structural weakness due to structure-bound Cu(II) in F-containing hectorite. Our results suggest that traces of Cu(II), typical of natural environments, may influence the conversion products in high-temperature geochemical systems.
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Citation
Clays and Clay Minerals, Vol. 57, No. 2, 139–149, 2009
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