Ion exchange in zeolites. Part 4.—Hydrolysis and trace 134Cs+ exchange in K- and Na-mordenite

Abstract

Trace ¹³⁴Cs⁺ exchange and concurrent hydrolysis (H₃O⁺ exchange from water) have been studied in Na-mordenite and K-mordenite with special emphasis on prediction of these equilibria. The predictions were generally good, or adequate, in higher and intermediate total ion concentrations, but deviated markedly from observations in dilute solutions. For trace ¹³⁴Cs⁺ equilibria, these deviations arose largely from the association of ¹³⁴Cs⁺ ions with a colloidal suspension in the solution phase. The particle size of the suspension was very small: it was possible that a considerable fraction of it was below 3 nm. In addition to binary Cs⁺–Na⁺ and Cs⁺–K⁺ exchanges, trace ¹³⁴Cs⁺ exchange in the ternary system Cs⁺–Na⁺–K⁺ was investigated and the methods for the prediction of the ternary equilibria discussed.