THE RADIOCHEMISTRY OF PLUTONIUM - Sciencemadness.org

Di-acidic compounds. Mono-2- ethylhexylphosphoric acid has been most
extensively studied of this type of compound. It is polymeric in the orgamic phase in
a non-polar solvent,
such as ~enzene310, 130
and extracts primarily by the ion exchange re-
action.
Kos yakov et al. 238 studied the extraction of Am(III), Pu(l!V), NP(V), and U(VI)
by mono-2- ethylhexylphosphoric acid (H2MEHP) from nitric acid solutions with results
shown in Fig. 17. The distribution coefficients are in general higher for the same
aqueous conditions than those of HDEHP. Pu(IV) can be returned to the aqueous phase
by washing with a 5 ~. solution of potassium oxalate.
5.0 -
4.0
t
~ 2.0 -
:
-1
I.0 –
o -
-1.0 -
NP(E)
1 I I I
-2.o~
-1.0 -0.5 0 0.5 1.0
Log HN03 CONCENTRATION (M)
Fig. 17. Extraction of various actinides into 0.2 ~ H2MEHP (isooctane diluent ) from
HN03 solutions.238
Peppard et al, 313, 270 studied the extraction of several actinides by H2MEHP
from HC1 solutions (Fig. 18). The distribution coefficient for Np(IV) at 12 ~ HC1 is
over 103 and is a factor of 104 greater than the other non-tetravalent species studied.
Separation from Pu is accomplished by. reduction of the Pu to the tripositive state.
Gindler ~. 14’ used this method to purify
236
Pu for fission counting. The Np(IV) can
be returned to the aqueous phase by the addition of TBP to the organic phase, resulting
in a great reduction in the distribution coefficient because of anti- synergistic (or
antagonistic) effect of these reagents, (cf Mixed ExtractantsJ p. 71).
Applications of acidic compounds. Acidic compounds have been used in
several applications in Pu chemistry. Kosyakov et al. 238 used HDEHP to purify Am(lII)
from other actinides of higher valence state, and accomplish their mutual separation
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