Abstract
The hydrothermal transformation of kaolinite to basic sodalite Na 8[AlSiO 4] 6 (OH · H 2O) 2 and hydroxoborate sodalite Na 8[AlSiO 4] 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.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
