An Assessment of Inorganic Ion-Exchange Materials for the Removal of Strontium from Simulated Hanford Tank Wastes

Abstract

Several inorganic ion-exchange materials were evaluated for the removal of strontium from two simulated Hanford tank wastes (NCAW and 101SY-Cs5) using static batch experiments. Sodium titanium silicate, Na2Ti2O3SiO4·2H2O(NaTS), was the best material in NCAW with a K d of 2.7 × 105 mL/g at a volume-to-mass ratio of 200:1. In the 101SY-Cs5 simulant, strontium extraction was more difficult due to the presence of complexants and consequently K ds were greatly reduced. Sodium nonatitanate, NaTi, performed best in the presence of these complexants and gave a K d of 295 mL/g, though none of the materials performed particularly well. Pellets suitable for column studies were synthesized and the ion exchangers evaluated in column studies. Breakthrough curves correlated well with the K ds obtained from batch experiments with the sodium titanium silicate performing best in NCAW and a pelletized form of sodium nonatitanate performing best in 101SY-Cs5. Both the sodium titanate and the sodium titanosilicate performed better than IONSIV IE-911, a commercially available ion exchanger, in the NCAW simulant, and consequently could be used for the removal of 90Sr from highly alkaline tank wastes.