Surface Area Changes of a Vermiculite by Acid and Thermal Treatment

Juan de D. Lopez-Gonzalez1 and Jesus Cano-Ruiz
Laboratorios de Quimica Inorganica de la Universidad de Granada y Estacion Experimental del Zaidin, Granada, Spain
1 Present address: Department of Soils and Plant Nutrition, University of California at Berkeley.

Abstract: A vermiculite from Beni-Uxera, North Africa, was refluxed with HCl solutions of various concentrations to determine the effect of such a treatment on its surface area. The treated vermiculite was analyzed for “free” SiO2 and by x-ray diffraction, and the refluxing solutions were analyzed for the cations removed from the vermiculite. Surface areas were determined by means of adsorption isotherms of n-butane at 0°C.

The surface area of the acid-treated vermiculite increases with increase in concentration of the acid. Heating of the acid-treated samples or the natural samples decreases the surface area.

The increase in surface area by acid treatment is due to destruction of the vermiculite and its conversion to a “free” form of SiO2 which possesses a large surface area. x-Ray analysis indicated that this “free” SiO2 was not present in the interlayer positions of the crystal lattice of vermiculite.

Clays and Clay Minerals; 1957 v. 6; no. 1; p. 399-405; DOI: 10.1346/CCMN.1957.0060130
© 1957, The Clay Minerals Society
Clay Minerals Society (www.clays.org)