Influence of the Nb content and microstructure of sitinakite-type crystalline silicotitanates (CSTs) on their Sr2+ and Cs+ sorption properties

Radioactive wastewater contaminated with 137Cs and 90Sr are produced at different stages of the nuclear fuel cycle. Transferring these radionuclides to a stable solid matrix is crucial for safe management long-term storage. Sitinakite Crystalline silicotitanates (CSTs) among most selective mineral ion exchangers Cs and/or Sr depending on pH medium CST chemical composition (Nb doping). To better understand how their microstructure affects sorption properties, CSTs morphologies (consisting submicronic micronic particles) Nb contents (from 0% 25%) were synthesized characterized in terms Sr2+ Cs+ properties moderately basic pH. The Sr2+/Na+ Cs+/Na+ equilibrium exchange diagrams obtained highlight presence two kind sites selectivities capacities. first, site, highly less pH, was attributed “tunnel” structure. second one, Cs, seems be surface site. Although doping found promote hinder alkaline accessibility selectivity depend more strongly CSTs. Results indicate that crystalline, particles, fewer structural defects, Sr, but larger specific areas (greater number sites) afforded by particles associated