Hydrothermal Formation of a Kaolinite-Like Product from Noncrystalline Aluminosilicate Gels1

C. R. De Kimpe2, H. Kodama3 and R. Rivard2
1 Contribution 181 Research Station, Ste-Foy and 1230 CBRI, Ottawa.
2 Agriculture Canada, Research Station, 2560, boul. Hochelaga Ste-Foy, Québec, Canada GlV 2J3.
3 Agriculture Canada, CBRI, Central Experimental Farm, Ottawa, Ontario, Canada K1A 0C6.

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.

Key Words: Aluminosilicate • Gel • Infrared spectroscopy • Kaolinite • Synthesis • X-ray powder diffraction

Clays and Clay Minerals; December 1981 v. 29; no. 6; p. 446-450; DOI: 10.1346/CCMN.1981.0290605
© 1981, The Clay Minerals Society
Clay Minerals Society (www.clays.org)