INORGANIC ION EXCHANGE MATERIALS FOR THE REMOVAL OF STRONTIUM FROM SIMULATED HANFORD TANK WASTES

摘要

Both the sodium nonatitanate, NaTi, and the sodium titanosilicate, NaTS, were highly efficient at removing strontium from NCAW, with greater than 99.9 percent of the total strontium removed by both materials in batch experiments. Column studies confirmed the high affinity of both of these materials, particularly NaTS, for strontium in the presence of high alkalinity and high concentrations of inert salts. However, column blockage proved to be a problem due to precipitation of salts within both the column and the tubing which may cause problems in the application of these materials on a plant scale. All materials performed poorly in removing strontium from 101SY-Cs5 due to the presence of high concentrations of complexants and K_ds in batch experiments were reduced from >200,000 mL/g for NCAW to <250 mL/g for the 101SY-Cs5. All of the column experiments showed almost immediate breakthrough of strontium except for a sample of sodium nonatitanate provided by AlliedSignal which did not reach 50 percent breakthrough until nearly 125 BVs. This materials contains essentially the same nonatitanate as the pelletised A&M titanate and its superior performance must therefore be a result of an improved pelletising procedure or the incorporation of less inorganic binder. The potassium pharmacosiderite, KTS-Ph, did not perform as well as either NaTS or NaTi in any of the waste simulants. This material has, however, been found to be more suitable for the removal of strontium and caesium from groundwaters and other process wastes with a lower total ionic strength.