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Hydrothermal Formation of a Kaolinite-Like Product from Noncrystalline Aluminosilicate Gels

Published online by Cambridge University Press:  01 July 2024

C. R. De Kimpe ,
H. Kodama  and
R. Rivard
C. R. De Kimpe
Affiliation:
Agriculture Canada, Research Station, 2560, boul. Hochelaga, Ste-Foy, Québec, Canada GlV 2J3
H. Kodama
Affiliation:
Agriculture Canada, CBRI, Central Experimental Farm, Ottawa, Ontario, Canada K1A 0C6
R. Rivard
Affiliation:
Agriculture Canada, Research Station, 2560, boul. Hochelaga, Ste-Foy, Québec, Canada GlV 2J3
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Abstract

Noncrystalline aluminosilicate gels with Al2O3/(Al2O3 + SiO2) weight ratios from 0.3 to 0.5 were reacted in 0.1 N KOH at temperatures varying from 125° to 175°C. The pH of the solutions dropped sharply with increasing gel:solution ratios, indicating that the coordination number of Al in the products changed from IV to VI. The degree of hydrolysis appeared to be higher with KOH than with NaOH. X-ray powder diffraction and infrared spectroscopy showed that disordered kaolinite was the only crystalline product formed. Thermal data and surface area measurements indicated that the kaolinite was formed by a condensation process.

Резюме

Резюме

Некристаллические кремнеалюминиевые жели с весовыми номерами Аl2O3/(Аl2O3 + SiO2) от 0,3 до 0,5 реагировали в 0,1 N растворе КОН в диапазоне температур 125°–175°С. Величина pH растворов уменьшалась быстрее, если соотношение желе/раствор увеличивалось, указывая на то, что координационное число алюминия в продуктах изменилось от IV до VI. Степень гидролиза являлась выше для КОН, чем для NaOH. Порошковая рентгеновская дифракция и инфракрасная спектроскопия показали, что только неупорядоченный каолинит формировался как кристаллический продукт. Данные по термоанализу и измерению площади поверхности показали, что каолинит образовывался путём процесса конденсации. [Е.С.]

Resümee

Resümee

Nichtkristalline Aluminosilikat-Gele mit Al2O3/(Al2O3 + SiO2)-Gewichtsverhältnissen von 0,3 bis 0,5 wurden in 0,1 N KOH bei Temperaturen von 125° bis 175°C zur Reaktion gebracht. Der pH-Wert der Lösungen nahm mit zunehmenden Gel/Lösung-Verhältnissen sehr stark ab. Dies deutet darauf hin, daß sich die Koordinationszahl von Aluminium in den Produkten von IV nach VI änderte. Der Hydrolysegrad schien bei KOH höher zu sein als bei NaOH. Röntgenpulverdiffraktometrie und Infrarotspektroskopie zeigten, daß ein ungeordneter Kaolinit das einzige kristalline Produkt war. Thermische Daten und Oberflächenmesungen deuteten darauf hin, daß der Kaolinit durch einen Kondensationsprozeß gebildet wurde. [U.W.]

Résumé

Résumé

Des aluminosilicates non cristallins, de rapport moléculaire Al2O3/(Al2O3 + SiO2) variant de 0,3 à 0,5, ont été traités en présence de KOH 0,1 N à des températures de 125° à 175°C. La forte diminution du pH des solutions pour des rapports gebsolution croissants indique un changement du nombre de co-ordination de l'aluminium de IV à VI dans les produits de réaction. L'hydrolyse des gels est plus prononcée en présence de KOH que dans NaOH. La diffraction des rayons-X et la spectroscopie infrarouge ont permis d'identifier une kaolinite peu ordonnée comme seul produit de réaction cristallin. L'analyse thermique et les mesures de surface spécifique ont montré qu'un mécanisme de condensation était à l'origine de la cristallisation de la kaolinite.

Keywords

AluminosilicateGelInfrared spectroscopyKaoliniteSynthesisX-ray powder diffraction
Type
Research Article
Information
Clays and Clay Minerals , Volume 29 , Issue 6 , December 1981 , pp. 446 - 450
Copyright
Copyright © 1981, The Clay Minerals Society

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Footnotes

1

Contribution 181 Research Station, Ste-Foy and 1230 CBRI, Ottawa, Canada

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