The kinetics of dehydration in Ca-montmorillonite: An in situ X-ray diffraction study

Helen J. Bray; Simon A.T. Redfern; Simon M. Clark

doi:10.1180/002646198548034

The kinetics of dehydration in Ca-montmorillonite: An in situ X-ray diffraction study

Helen J. Bray^*, Simon A.T. Redfern, Simon M. Clark

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

88 Citations (Scopus)

Abstract

The thermal dehydration of naturally occurring Ca-montmorillonite has been studied by in situ X-ray diffraction at temperatures between 60-120°C. The time-temperature-dependence of the position of the basal (001) reflection reveals that interlayer water loss on isothermal dehydration occurs in two stages. After an initial rapid decrease in interlayer spacing (on shock heating to an isothermal soak temperature) the reaction proceeds towards equilibrium more slowly. Furthermore, the width of the (001) reflection changes with time, reflecting transformation-dependent changes in homogeneity perpendicular to (001) with a maximum in peak width at the point where the rate of the reaction appears to change. This suggests that, as the interlayer spacing collapses, a local change is induced in the structure, affecting the means of movement of the water from the interlayer.

Original language	English
Pages (from-to)	647-656
Number of pages	10
Journal	Mineralogical Magazine
Volume	62
Issue number	5
DOIs	https://doi.org/10.1180/002646198548034
Publication status	Published - Oct 1998
Externally published	Yes

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title = "The kinetics of dehydration in Ca-montmorillonite: An in situ X-ray diffraction study",

abstract = "The thermal dehydration of naturally occurring Ca-montmorillonite has been studied by in situ X-ray diffraction at temperatures between 60-120°C. The time-temperature-dependence of the position of the basal (001) reflection reveals that interlayer water loss on isothermal dehydration occurs in two stages. After an initial rapid decrease in interlayer spacing (on shock heating to an isothermal soak temperature) the reaction proceeds towards equilibrium more slowly. Furthermore, the width of the (001) reflection changes with time, reflecting transformation-dependent changes in homogeneity perpendicular to (001) with a maximum in peak width at the point where the rate of the reaction appears to change. This suggests that, as the interlayer spacing collapses, a local change is induced in the structure, affecting the means of movement of the water from the interlayer.",

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year = "1998",

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AU - Redfern, Simon A.T.

AU - Clark, Simon M.

PY - 1998/10

Y1 - 1998/10

N2 - The thermal dehydration of naturally occurring Ca-montmorillonite has been studied by in situ X-ray diffraction at temperatures between 60-120°C. The time-temperature-dependence of the position of the basal (001) reflection reveals that interlayer water loss on isothermal dehydration occurs in two stages. After an initial rapid decrease in interlayer spacing (on shock heating to an isothermal soak temperature) the reaction proceeds towards equilibrium more slowly. Furthermore, the width of the (001) reflection changes with time, reflecting transformation-dependent changes in homogeneity perpendicular to (001) with a maximum in peak width at the point where the rate of the reaction appears to change. This suggests that, as the interlayer spacing collapses, a local change is induced in the structure, affecting the means of movement of the water from the interlayer.

AB - The thermal dehydration of naturally occurring Ca-montmorillonite has been studied by in situ X-ray diffraction at temperatures between 60-120°C. The time-temperature-dependence of the position of the basal (001) reflection reveals that interlayer water loss on isothermal dehydration occurs in two stages. After an initial rapid decrease in interlayer spacing (on shock heating to an isothermal soak temperature) the reaction proceeds towards equilibrium more slowly. Furthermore, the width of the (001) reflection changes with time, reflecting transformation-dependent changes in homogeneity perpendicular to (001) with a maximum in peak width at the point where the rate of the reaction appears to change. This suggests that, as the interlayer spacing collapses, a local change is induced in the structure, affecting the means of movement of the water from the interlayer.

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JO - Mineralogical Magazine

JF - Mineralogical Magazine

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ER -

The kinetics of dehydration in Ca-montmorillonite: An in situ X-ray diffraction study

Abstract

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