Cation-Exchange Reactions of Siliceous and Aluminous Phillipsites

Yasuhiro Shibue1
Department of Earth Science and Astronomy, College of General Education, University of Tokyo, Komaba, Meguro-ku, Tokyo 153, Japan
1 Present address: Geological Institute, Faculty of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan.

Abstract: Exchange isotherms for the pairs Na-K and Na-Ca were measured by use of 0.1 N solutions at 5°, 35°, and 70°C in phillipsite from Tecopa, California (3.63 Al/32 oxygen unit cell), and Oki Islands, Shimane Prefecture, Japan (6.31 Al/32 oxygen unit cell). All isotherms except those for Na-Ca at 5°C were reversible. Free energy was evaluated for all reversible exchanges. The thermodynamic affinity sequences were K > Na > Ca in both phillipsites. The selectivity for K in competition with Na and that for Na competing with Ca became larger at the lower temperatures. The siliceous phillipsite preferred the larger cation more strongly for the Na-K system, and Na more strongly for the Na-Ca system than the aluminous phillipsite.

Key Words: Cation exchange • Cation selectivity • Chemical composition • Phillipsite • Zeolite

Clays and Clay Minerals; October 1981 v. 29; no. 5; p. 397-402; DOI: 10.1346/CCMN.1981.0290509
© 1981, The Clay Minerals Society
Clay Minerals Society (www.clays.org)