Actinides extractability trends for multidentate diamides and phosphine oxides

Sasaki, Yuji  ; Kitatsuji, Yoshihiro  ; Sugo, Yumi; Tsubata, Yasuhiro   ; Kimura, Takaumi ; Morita, Yasuji  

Diamides and phosphine oxides having many kinds of the central frames were synthesized and employed in order to see the behavior of actinides(An)(III), (IV), (V) and (VI). Diamides synthesized here have two, three, or four donor atoms of amidic and etheric oxygen (nitrogen or sulfur, instead) atoms in their central frames, namely the extractants can work as bi-, tri-, and tetradentate modes. Di-phosphine di-oxides ((Bis(diphenylphosphoryl)methane (BDPPM) and bis(diphenylphosphoryl)ethylene (BDPPE)), carbamoylmethylphosphine oxide (octylphenyl-,-diisobutyl-carbamoylmethylphosphine oxide (CMPO)) are used as the representative actinide extractants. Metal ions of Eu(III), Th(IV), U(VI), Np(V), Pu(IV) and Am(III) in perchloric acid were extracted into nitrobenzene or n-dodecane. Measurement of value at the different extractant concentration gives the information on extraction reaction and their extraction ability. From the present work, the best extractant is BDPPM, due to the strong affinity concerning P=O and form of the bidentate mode with six-membered ring chelation. However, this extractant have low solubility in -dodecane. Taking the applicatory properties, e.g., high solubility in -dodecane, easy organic synthesis, gasification by combustion and high actinide extractability, into consideration, diglycolamide (DGA) is a promising extractant for radioactive waste treatment.