Extraction separation of americium(III) and europium(III) by thermosensitive polymer gel copolymerized with TPEN derivatives

TPEN誘導体を共重合した感温性ポリマーゲルによるAm(III)とEu(III)の抽出分離

竹下 健二*; 石田 圭吾; 中野 義夫*; 松村 達郎  

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

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(tppen)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の水相中において膨潤状態でAm(III)の分配係数2000とAm/Euの分離係数20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 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, and such conformational change was repeated stably by the thermal-swing operation between 5C and 40C. Then, a trivalent actinide, Am(III), was extracted selectively in the swollen gel at 5C and released easily by the conformational change of polymer network to the shrunken state with the increase of temperature to 40C. The distribution ratio of Am(III) and the separation factor between Am(III) and Eu(III) were evaluated as 2000 and 20 in the swollen gel. These values are sufficient to the establishment of a practical MA recovery process.