Internal Surface Area of Wyoming Bentonite from Swelling Relationships

D. H. Fink
U.S. Water Conservation Laboratory, USDA-ARS, Phoenix, Arizona 85040, U.S.A.

Abstract: The internal surface area of Na-Wyoming bentonite was determined for linearly swelling pastes, using a physically based equation which describes such swelling. Information required is simply the linear relationship between interplatelet spacing, determined by X-ray powder diffraction, vs total water content determined gravimetrically. However, before the three-unknown parameter equation can be so applied, that portion of external-pore water, which normally increases linearly commensurately as interstitial water increases, must be decreased to zero. This was accomplished by adding dilute quantities of NaCl salt to the clay-paste system to decrease the attractive forces between positive-edge and negative-face sites, and stirring vigorously to further destroy the card-house structure and align the clay platelets.

Clays and Clay Minerals; July 1977 v. 25; no. 3; p. 196-200; DOI: 10.1346/CCMN.1977.0250304
© 1977, The Clay Minerals Society
Clay Minerals Society (www.clays.org)