Cation Retention By Montmorillonite in Constrained Environments.

The retention of cations on montmorillonite was studied in constrained and non-constrained environments. Montmorillonite clay minerals were placed in a stainless steel column to limit the expansion of the interlayers. In contrast, montmorillonite clay minerals were suspended in solution for free expansion of the interlayers. The Na⁺, Ca²⁺, Mg²⁺ ions were the dominant native cations present in the montmorillonite clay mineral. The amount of Cs⁺ added were the same as native Na⁺ present in the montmorillonite clay minerals. At equilibrium, the adsorption of Cs⁺ is significantly higher than Na⁺ both in column and suspension. The adsorption of Cs⁺ in suspension is significantly higher than in column, while the adsorption of Na⁺, Ca²⁺ and Mg²⁺ in suspension were significantly lower than in column. Our research showed that retention of cations on montmorillonite was influenced by cation species and the physical dimensions of the montmorillonite interlayers.