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Reexamination of the Kinetics of the Thermal Desorption of Dimethylsulfoxide and N-Methyl Formamide from a Greensplatt Kaolin

Published online by Cambridge University Press:  02 April 2024

Christopher Breen  and
Sean Lynch
Christopher Breen*
Affiliation:
School of Chemical Sciences, National Institute for Higher Education, Glasnevin, Dublin 9, Ireland
Sean Lynch
Affiliation:
School of Chemical Sciences, National Institute for Higher Education, Glasnevin, Dublin 9, Ireland
*
1Current address: Chemistry Department, Sheffield City Polytechnic, Pond Street, Sheffield S1 1WB, United Kingdom.
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Abstract

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The kinetics of the thermal decomposition of the kaolin: dimethylsulfoxide (kaolin: DMSO) and the kaolin: N-methylformarnide (kaolin: NMF) intercalates have been reexamined. Two different sample sizes (2 mg and 8 mg) and grain-size distributions (<45 μm and 45–63 μm were investigated using isothermal and dynamic gravimetry in the temperature range 100°–200oC. All sample configurations for the kaolin: DMSO intercalate (2 mg, <45 μm; 2 mg, 45–63 μm; 8 mg, <45 μm; 8 mg, 45–63 μm) followed the rate law -ln(1 - α) = kt to a value for α, the reaction fraction complete, of.6, yielding activation energies and standard deviations at the 99% confidence level of 85.5 ± 3.79 and 71.75 ± 8.75 kJ/mole for the isothermal and dynamic runs, respectively. The kaolin: NMF intercalate (2 mg, <45 μm) also followed the same rate law for α <.8, with activation energies and standard deviations at the 99% confidence level of 89 ± 5.05 and 79.25 ± 6.47 kj/mole for the isothermal and dynamic studies, respectively. In solution the rate law -ln(1 - α) = kt is known as first-order kinetics, but here it appears to represent the non-instantaneous nucleation of uniformly sized particles, followed by the inward movement of a reaction interface.

Keywords

Activation energyDesorptionDimethylsulfoxideKaoliniteN-methyl formamideThermal treatment
Type
Research Article
Information
Clays and Clay Minerals , Volume 36 , Issue 1 , February 1988 , pp. 19 - 24
Copyright
Copyright © 1988, The Clay Minerals Society

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