Comparison of organic and inorganic ion exchangers for the batch contact removal of cesium and strontium from simulated and actual Hanford 241-AW-101 DSSF tank waste

This report describes the evaluation of seven ion exchange materials (sodium nonatitanate (NaTi), CS-100, resorcinol-formaldehyde (R-F), SuperLig reg-sign 644, IONSIV reg-sign IE-910, IE-911, and TIE-96) for pretreatment of actual and simulated Hanford tank waste. The data can be applied to the development and evaluation of pretreatment process flowsheets. Cs and Sr batch distributions ratios (Kd) column distribution ratios (λ= Kd x ρb), and decontamination factors (DF) are compared as a function of supernate:exchanger phase ratio, solution composition, and multiple sequential contacts. The actual double shell slurry feed (DSSF) waste used was a volume composite from tanks 101-AW (70%), 106-AP (20%) and 102-AP (10%) diluted to 4.96 ± 0.19 M sodium with an initial Na/Cs ratio of 78,000. Simulant tests were conducted at waste dilutions ranging from 7 to 0.2 M Na, over a wide range of Na/Cs mole ratios (50 to 500,000). For all materials, the cesium λ values increased with Na/Cs ratio (decreasing cesium concentration) and decrease with increasing sodium concentration. Cs λ values varied from 2 to 6.0E+04 with the following order over most solution conditions: IE-910 ∼ IE-911 > SL-644 ∼ R-F > TIE-96 > CS-100. There was general agreement between the Cs λ results obtained with the simulant and actual waste. All materials had an affinity for strontium with the NaTi providing the greatest removal followed by IE-911, IE-910, and TIE-96. The organic exchangers exhibited relatively low affinities and would not be useful for strontium removal. The actual waste strontium λ results were significantly lower than those obtained during simulant testing and are likely due to higher levels of organic materials or nonradioactive strontium in the actual waste solution. These data suggest that future testing will be necessary to address the issue of significant metals uptake