Studies on a synthetic sitinakite-type silicotitanate cation exchanger: Part 1: Measurement of cation exchange diffusion coefficients

A commercially available synthetic silicotitanate (IONSIV® IE-911), with a sitinakite-like structure, is a candidate material for the remediation of aqueous nuclear waste streams. These streams are often complex in their cation composition. This work investigates the effect of the presence of Na, K, Mg, Ca and Ba on the rates of removal of Cs and Sr radioisotopes as cations of importance in aqueous nuclear waste streams. Results are compiled as isotopic diffusion coefficients, and by analysis of changes in pH with time, observed as the systems reach equilibrium. This kinetic treatment provides necessary data for use in the modelling of plant performance and for the accurate determination of distribution coefficients which will be the subject of the second part in this series.