Ion exchange of 85Sr, 134Cs and 57Co in sodium titanosilicate and the effect of crystallinity on selectivity

The uptake of 85Sr, 134Cs and 57Co on a framework sodium titanosilicate of an ideal formula Na2Ti2O3(SiO4) · 2H2O was investigated. Samples of varying crystallinity were synthesized and this effect on cation affinity was studied. The material exhibited high affinity for cesium in slightly acidic to alkaline solutions, but potassium and the presence of sodium at high pH interfered significantly with selective 134Cs uptake. The weakly acidic exchanger took up 85Sr and 57Co efficiently above neutral pH in 0.1 M NaNO3. The crystallinity of the material proved to be an important factor in efficient removal of 85Sr from calcium bearing effluents. The semi-crystalline titanosilicates had a high affinity for 85Sr over Ca2+ at neutral pH. The affinity for cesium in the presence of potassium was improved as well in samples of lower crystallinity.