Determination of Surface Areas of Mineral Powders by Adsorption Calorimetry1

Kenneth V. Ticknor and Preet P. S. Saluja
Atomic Energy of Canada Limited, Whiteshell Nuclear Research Establishment Pinawa, Manitoba R0E 1L0, Canada
1 Issued as Atomic Energy of Canada Limited publication, AECL-9925.

Abstract: Adsorption calorimetry was used to develop a method for determining the surface area of low-surface-area materials (< 1 m2/g), which required no pretreatment of the surface, such as outgassing at elevated temperatures. The method involved flowing heptane through a small amount of sample (0.15 to 1.0 g) in the flow cell of a commercial microcalorimeter. When thermal equilibrium was reached at the powder-heptane interface, pure heptane was replaced with a heptane carrier-solution containing 0.6 volume % n-butanol (n-BuOH) as the preferential adsorbate. The integral enthalpy of preferential saturation adsorption, ΔHsat, of n-BuOH on the surface was found to be a function of the BET surface area of the sample. An empirical relationship between ΔHsat, and BET surface area was determined over a surface area range of about three orders of magnitude (0.095 to 81 m2/g) by performing adsorption experiments on five α-alumina standard reference powders. The technique was applied to the determination of surface areas of untreated rock and mineral powders.

Key Words: Adsorption calorimetry • α-Alumina • n-Butanol • Fracture-filling minerals • Surface area

Clays and Clay Minerals; August 1990 v. 38; no. 4; p. 437-441; DOI: 10.1346/CCMN.1990.0380413
© 1990, The Clay Minerals Society
Clay Minerals Society (www.clays.org)