Thermal-swing extraction separation of Am(III) and Eu(III) with poly-NIPA gel crosslinked with TPEN derivative

TPEN誘導体によって架橋されたポリNIPAゲルによるAm(III)とEu(III)の温度スイング抽出分離

竹下 健二*; 松村 達郎  ; 中野 義夫*

Takeshita, Kenji*; Matsumura, Tatsuro; Nakano, Yoshio*

ポリ-N-イソプロピルアクリルアミド(NIPA)を六座の窒素ドナー配位子であるN,N,N',N'-tetrakis(4-propenyloxy-2-pyridylmethyl)ethylenediamineによって架橋した感温性ゲルを合成した。このポリマーネットワークは膨潤収縮特性に温度依存性を持ち、低温のpH5.3の水相中における膨潤状態でAm(III)の分配係数2000とAm/Euの分離係数18を確認した。また、Am(III)は温度上昇によるゲルの収縮によって放出されることを確認した。この特性は、このゲルを用いて温度スイングオペレーションを行うシンプルなMA/Ln分離プロセスの構築の可能性を示唆している。

The extraction separation of trivalent minor actinides from lanthanides was examined by a thermosensitive gel, poly-NIPA (N-isopropyl acrylamide) crosslinked with a TPEN derivative, N,N,N',N'-tetrakis(4-propenyloxy-2-pyridylmethyl)ethylenediamine (tppen). The synthesized gel showed the conformational change of polymer network with temperature, which is known as the phase transition phenomena of gel, and such conformational change was repeated stably by the thermal-swing operation between 5C and 40C. Then, Am(III) was extracted selectively in the swollen gel at 5C and released easily from the shrunken gel at 40C. The distribution ratio of Am(III) and the separation factor between Am(III) and Eu(III) were evaluated as 2000 and 18 in the swollen gel. These values are sufficient to the establishment of a practical MA recovery process. Then, both the extractability and selectivity of Am were maintained stably and the selective extraction of Am was attainable by the simple thermal-swing operation. These results suggest that the proposed gel extraction process is applicable to a MA partitioning for transmutation.