Anomalous extraction behavior of americium(III) in some diglycolamide isomers present in ionic liquid medium

AbstractThe alkyl derivatives of diglycolamide (DGA) such as N,N,N´,N´-tetraoctyldiglycolamide (TODGA), N,N,N´,N´-tetraethylhexyldiglycolamide (TEHDGA) and N,N-diethylhexyl- N´,N´-dioctyldiglycolamide (DEHDODGA) are chain isomers differing only in the arrangement of carbon chain of the alkyl group. The extraction behavior of Am(III) in the solution of these diglycolamides in ionic liquid medium was studied as a function of concentration of nitric acid and diglycolamide. The results were compared with those obtained in a molecular diluent, n-dodecane. The extraction of Am(III) in ionic liquid medium increased in the order TEHDGA<TODGA< DEHDODGA, which was different from the customary trend of TEHDGA<DEHDODGA< TODGA obtained in n-DD. The anomaly observed in ionic liquid medium was probed by IR spectroscopy and measurement of stoichiometry. The stoichiometry of Am : DGA in each case was different and that exhibited a strong influence on the observed extraction trend. The unprotonated fraction of DGA, assessed from FTIR measurements, increased in the order TEHDGA<TODGA<DEHDODGA, which seems to be responsible for the observed anomalous extraction trend in DEHDODGA in ionic liquid medium.