Palygorskite Separation from Dodecylammonium-Treated Clays

G. Abudelgawad, B. E. Viani1 and J. B. Dixon
Faculty of Agriculture, Alfateh University, Tripoli, Libya
Department of Soil and Crop Sciences, Texas A&M University College Station, Texas 77843
1 Present address: Arco Oil and Gas Company, Exploration & Production Research, P.O. Box 2919, Dallas, Texas 75221.

Abstract: Three methods were investigated to separate palygorskite from mixtures of clay minerals in soils and sediments. The methods were based on the hydrophobic properties of a dodecylammonium-smectite complex and used the <0.2-µm fractions of reference palygorskites that contained smectite and sepiolite impurities. Palygorskite was separated from dodecylammonium-clay complexes by: (1) selective dispersion of palygorskite in H2O; (2) selective extraction of palygorskite by a water:decanol phase separation; and (3) selective extraction of palygorskite by a water: nitrobenzene phase separation. Whereas all three methods resulted in palygorskite separation, selective dispersion was the simplest and employed the more desirable reagents. Small amounts of relatively pure palygorskite in the <0.2-µm fractions were concentrated from palygorskite-containing clays from Texas, Saudi Arabia, and Libya as shown by X-ray powder diffraction and transmission electron microscopy data. A sepiolite impurity in the Georgia palygorskite was concentrated with the palygorskite. Hydrolysis of the dodecylammonium-smectite complex was suggested by the decrease in d-spacing of some samples after the extensive washing necessary for dispersion. An appreciable amount of the fibrous mineral was intimately associated with layer silicates and could not be separated.

Key Words: Dodecylammonium smectite • Hydrophobic properties • Mineral separation • Palygorskite • Sepiolite • Smectite

Clays and Clay Minerals; October 1985 v. 33; no. 5; p. 438-442; DOI: 10.1346/CCMN.1985.0330510
© 1985, The Clay Minerals Society
Clay Minerals Society (www.clays.org)