BARC/PUB/2017/1523

 
 

Extraction of plutonium(IV) by diglycolamide extractants in room temperature ionic liquids

 
     
 
Author(s)

Prabhu, D. R.; Raut, D. R.; Murali, M. S.; Mohapatra, P. K.
(RCD)

Source

Radiochimica Acta, 2017. Vol. 105 (4): pp. 285-293

ABSTRACT

Extraction  of  Pu(IV)  was  investigated  using  solutions of two diglycolamide extractants viz., N,N,N′,N′-tetra-n-octyldiglycolamide  (TODGA) and its branched homolog,  N,N,N′,N′-tetra(2-ethylhexyl)   diglycolamide   (T2EHDGA),   dissolved   in   two   imidazolium   based   room   temperature   ionic liquids viz., 1-butyl-3-methylimidazolium bis(trifluoromethanesulphonyl) imide ([C4mim][NTf2]) and   1-octyl-3-methylimidazolium bis(trifluoromethanesulphonyl) imide  ([C8 mim][NTf2]) from  aqueous  nitric  acid  medium. The  extraction  kinetics  was  found  to  be  extremely  slow  which  is  reported  for  the first time for analogous extraction systems and took as long  as  30  h  to  attain  equilibrium  DPu  values.  In  general,  TODGA based solvents showed better extraction of Pu(IV) than  the  T2EHDGA  based  solvents,  one  order  of  magnitude higher, and though both the ionic liquids ultimately yielded comparable DPu values, attainment of equilibrium was slower with [C4mim][NTf2]. The extracted species conformed to 1:1 for TODGA in both the ionic liquids while a mixture of 1:1 and 1:2 species was observed for T2EHDGA at  1 M  HNO3  which  changed  to  1:1  species  at  4  M  HNO3. The extracted species is proposed to be (Pu (L) x4 +) IL (where, L  is  the  extractant  and  x = 1  or  2)  at  lower  acidities  suggesting  a  cation  exchange  mechanism  which  changes over  to  (Pu(NO3)4⋅L)IL  at  4  M  HNO3  conforming  to  a  solvation  mechanism  for  all  the  systems  except for  T2EHDGA[C8mim][NTf2]. UV-VIS spectroscopic studies were carried out to throw light on the nature of the extracted species.

 
 
SIRD Digital E-Sangrahay