Separation of Actinide(III) from Lanthanide(III) by thermosensitive gel copolymerized with TPEN derivatives

Takeshita, Kenji*; Fugate, G.*; Matsumura, Tatsuro  ; Nakano, Yoshio*; Mori, Atsunori*; Fukuoka, Sachio*

Extraction separation of Am(III) and Eu(III) was examined by the thermal-swing extraction technique using a thermosensitive gel, poly--isopropylacrylamide (NIPA) copolymerized with a TPEN derivative, -tetrakis(4-propenyloxy-2-pyridylmethyl)ethylenediamine (TPPEN). The separation of Am(III) from Eu(III) was observed in the swollen state of gel (5C) and the separation factor of Am(III) was evaluated as about 18 at pH5.2. More than 90% of Am(III) extracted into the gel was released by the volume phase transition of gel from the swollen state (5C) to the shrunken one (40C). The repetition test for the thermal swing extraction of a soft metal ion, Cd(II), which was used as a substitute of Am(III), was carried out and the extraction and release of Cd(II) were repeated three times stably under the thermal-swing operation between 5C and 40C. The radiation effect of gel on the extraction of Am and Eu was tested by the irradiation of -ray (10 kGy) and the long-term adsorption of -emitter (Cm). The TPPEN-NIPA gel sustained no damage by these radiation tests. These results suggest that the thermal-swing extraction technique is applicable to the MA partitioning process indispensable for the establishment of P&T technology.