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  • Author or Editor: T. Tranter x
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Abstract  

A novel approach to preparing granular sorbents for the separation of actinides has been developed, where the extractant is directly immobilized in an inert matrix. This allows substantially higher extractant loadings in the sorbent than for conventional extraction chromatography resins. This approach utilizes polyacrylonitrile (PAN) as the inert matrix material. The well-known actinide extractant octyl (phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) has been loaded into sorbent granules at extractant loadings from 20 to 33 wt.% CMPO. The porosity of the PAN matrix allows the active material to have rapid and complete access to the solution containing the impurities, resulting in improved kinetics and higher sorption capacities. Sorbents containing CMPO were prepared using PAN as a binding matrix, and tested against commercially available actinide extraction chromatography resins. Direct comparative batch contact tests performed with TRU-ResinÒ and CMPO-PAN using an INEEL tank waste simulant, resulting in distribution coefficient (K d) values for Am approximately 2-90 times higher for CMPO-PAN than for TRU-Resin. Batch distribution coefficient (K d) values for Pu were approximately 60-150 times higher for CMPO-PAN than for the TRU-Resin. Acid dependency curves were generated for Am and Pu with CMPO-PAN over a concentration range of 1 mM to 5M HNO3.

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Abstract  

A cloud point extraction method followed by inductively coupled plasma-mass spectrometry (ICP-MS) has been developed for the detection of trivalent lanthanides (Ln(III)) in aqueous samples. Ammonium pyrrolodinedithiocarbamate (APDC) was used as the chelating ligand with 2 wt% Triton X-114 as the surfactant. Various experimental parameters were investigated and the extraction efficiency, distribution ratios and concentration factors for the extraction of lanthanum (La), neodymium (Nd), europium (Eu) and thulium (Tm) were determined.

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Abstract  

Ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) composite sorbents have been evaluated for the removal of cesium from Idaho National Engineering and Environmental Laboratory (INEEL) concentrated acidic tank waste. Batch contacts were performed to qualitatively evaluate the effects of increased nitric acid, sodium and potassium. An equilibrium isotherm was generated with simulated concentrated tank waste solutions and fit to the Langmuir equation. Additional batch contact experiments were performed to determine if mercury, plutonium and americium would sorb onto AMP-PAN. Dynamic sorption was evaluated in column tests employing 1.5 cm3 columns operating at 5, 10 and 20 bed volumes of flow per hour. Results indicate, as expected, that dynamic cesium sorption capacity is reduced as the flowrate is increased. Calculated dynamic capacities for cesium were 22.5, 19.8 and 19.6 mg Cs/g sorbent, for 5, 10 and 20 bed volume per hour flows, respectively. The thermal stability of loaded AMP-PAN was evaluated by performing thermogrovimetric analysis (TGA) on samples of AMP, PAN (polymer), and AMP-PAN. Results indicate that AMP-PAN is stable to 400 °C, with less than a 10% loss of weight, which is at least partially due to loss of water of hydration. The evaluation of AMP-PAN indicates that it will effectively remove cesium from concentrated acidic tank waste solutions.

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