Evaluation of an extraction chromatographic resin containing CMPO and ionic liquid for actinide ion uptake from acidic feeds. Pt. II. Batch actinide sorption, radiolytic degradation and column studies

Extraction chromatographic resin prepared by impregnating CMPO-RTIL (C8mim+ . NTf2-) on Chromosrob-W for the removal of trivalent actinides and lanthanides from aqueous solutions showed a significant improvement over the previously reported CMPO-n-dodecane resin. The resin was characterized by thermal analysis, for surface area by BET and for surface morphology by SEM. The Kd value of Am(III) by CMPO-RTIL resin was found to be 5805 and 3.8 x 104 with 3 M and 0.01 M HNO3, respectively. The high Kd values at lower acidity suggested metal ion uptake following a cation exchange mechanism usually seen with ionic liquid based solvents and use of 0.01 M EDTA resulted in a Kd value of 0.11 which was subsequently used as the strippant. Uptake of other actinide ions such as UO22+, Pu4+, Np4+ and fission product element ions such as Eu3+, Sr2+ and Cs+ was also studied. Column studies using a feed containing 1 g/L Eu(III) in 3 M HNO3 suggested complete uptake of the metal ion up to passing 7 mL of the feed solution which corresponded to a column capacity of 7 mg of Eu. The loaded Eu(III) from the columns could be efficiently eluted with 0.01 M EDTA. The column capacity for Eu(III) was measured in the successive cycles of loading and elution and was found to be stable up to 60 d. The results suggested the possible application of the resins in the treatment of dilute laboratory radioactive waste. (orig.)