Phase IV Simulant Testing of Monosodium Titanate Adsorption Kinetics

Testing examined the extent and rate of strontium, plutonium, neptunium, and uranium removal from a 5.6 M Na solution by adsorption onto monosodium titanate (MST) at 0.2 and 0.4 g/L. Previously, Phase IV tests determined removal characteristics with solutions at 4.5M and 7.5M Na concentrations. These latest tests evaluated removal at the Na concentration expected for the Non-elutable Ion Exchange (N-IX) and Caustic Side Solvent Extraction (CSSE) flowsheets. Results indicated decreased sorbate removal from a 5.6M Na solution compared to a 4.5M Na solution. Strontium and plutonium removal produced equilibrium concentrations below Z-area feed limits under certain conditions, which indicated that the isotopic distribution of strontium and plutonium must be considered in design for feed blending strategies. Neptunium removal did not achieve the Z-Area limit at either MST concentration although the addition of 0.4 g/L MST nearly achieved the limit. The results indicated that strontium and plutonium removal rates decrease with increased sodium concentration (i.e., ionic strength). Neptunium and uranium removal proved lower from the 5.6M Na solution than the 7.5M Na solutions. These results provide additional data for sizing continuously stirred tank reactors for the Small Tank Tetraphenylborate (STTB) process and processing tanks for a strontium and alpha removalmore » unit operation in the CSSE and N-IX processes.« less