An assessment of inorganic ion-exchange materials for the removal of strontium from simulated hanford tank wastes

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. 2H(2)O ( NaTS), was the best material in NCAW with a K-d of 2.7 X 10(5) mL/g at a vo lume-to-mass ratio of 200:1. In the 101SY-Cs5 simulant, strontium extractio n was more difficult due to the presence of complexants and consequently K( d)s 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 th e materials performed particularly well. Pellets suitable for column studie s were synthesized and the ion exchangers evaluated in column studies. Brea kthrough curves correlated well with the Kds Obtained from batch experiment s with the sodium titanium silicate performing best in NCAW and a pelletize d 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 consequ ently could be used for the removal of Sr-90 from highly alkaline tank wast es.