The crystallization kinetics of sodalites grown by the hydrothermal transformation of kaolinite studied by ²⁹Si MAS NMR

authored by

J. Chr Buhl, W. Hoffmann, W. A. Buckermann, W. Müller-Warmuth

Abstract

The hydrothermal transformation of kaolinite to basic sodalite Na₈[AlSiO₄]₆ (OH · H₂O)₂ and hydroxoborate sodalite Na₈[AlSiO₄]₆ [B(OH)₄]₂ has been investigated at different temperatures (353 and 473 K). In the early stage of the reactions, the crystallization kinetics was studied by X-ray powder diffraction, thermogravimetry, IR spectroscopy and ²⁹Si MAS NMR spectroscopy. Besides the crystallization of the sodalites, no further intermediate phases were formed. MAS NMR of the ²⁹Si nucleus has been found to be a versatile tool to follow the progress of reactions from the signal ratio of the initial material and the crystallization product because the differences in chemical shifts result in well-separated signals. From these measurements, the growth rates of the sodalites could be determined quantitatively even for the very early stages of crystallization. It was found that sodium carbonate impurities in the NaOH solution used for the synthesis has an important influence on the reaction kinetics.

Organisation(s)

Institute of Mineralogy

External Organisation(s)

University of Münster

Type

Article

Journal

Solid State Nuclear Magnetic Resonance

Volume

9

Pages

121-128

No. of pages

8

ISSN

0926-2040

Publication date

12.1997

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Radiation, General Chemistry, Nuclear and High Energy Physics, Instrumentation

Electronic version(s)

https://doi.org/10.1016/S0926-2040(97)00052-0 (Access: Closed)