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Thermal analysis of pyridine-treated sepiolite and palygorskite

Published online by Cambridge University Press:  09 July 2018

U. Shuali
Affiliation:
Israel Institute for Biological Research, Ness Ziona, 70450, Israel
S. Yariv
Affiliation:
Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
M. Steinberg
Affiliation:
Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel
M. Müller-Vonmoos
Affiliation:
Laboratory for Clay Mineralogy, Institute of Foundation Engineering and Soil Mechanics, Federal Institute of Technology, Sonneggstrasse 5, CH 8092 Zurich, Switzerland
G. Kahr
Affiliation:
Laboratory for Clay Mineralogy, Institute of Foundation Engineering and Soil Mechanics, Federal Institute of Technology, Sonneggstrasse 5, CH 8092 Zurich, Switzerland
A. Rub
Affiliation:
Laboratory for Clay Mineralogy, Institute of Foundation Engineering and Soil Mechanics, Federal Institute of Technology, Sonneggstrasse 5, CH 8092 Zurich, Switzerland

Abstract

The thermal behaviour of sepiolite and palygorskite treated with pyridine (Py) was investigated by DTA, TG, DTG and EGA (by MS) under a flow of air and inert gases (N2 or Ar). The thermal analysis showed that the organic base was adsorbed by the clays, penetrating into the clay pores and replacing zeolitic and bound water. Its presence in the pores shifted the dehydroxylation peak to temperatures higher than the corresponding peak in the untreated clays. Under N2 and Ar, thermal desorption of Py from sepiolite was observed at 260 and 650°C whereas for palygorskite only traces of Py were detected in the evolved gases. In addition to desorption, reactions of pyrolysis and condensation to coke were detected by the evolution of ammonia, methane and hydrogen, respectively. In air, oxidation of the organic matter led to the appearance of exothermic peaks. The profile of the DTA curve and the temperatures of the most intense exothermic peaks were determined by the rate of the carbon oxidation.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1991

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