Cation exchange, interlayer spacing, and water content of MX-80 bentonite in high molar saline solutions

Cation exchange equilibria, interlayer spacing, and water content were determined for the Na-bentonite MX-80 equilibrated with 11 5.9 N model solutions. The model solutions were constant in K and Ca content and varied with respect to Na and Mg content. Analysis of cation exchange equilibria indicated the sorption of univalent chloro complexes of the type MCl + (M=Mg, Ca), the proportion in relation to sorbed Mg 2+ or Ca 2+ decreasing with increasing solution content of Mg in relation to Na. Interlayer spacing and total water content of compacted bentonite samples increased with increasing Mg content. Absolute numbers for pore water and interlayer water content still need to be confirmed by additional experiments.