THE RADIOCHEMISTRY OF PLUTONIUM - Sciencemadness.org

~uca245,246 . investigated a series of aliphatic ketones as extractants for Pu(IV).
His results, shown in Table IV- 23, show that the distribution of Pu(lT.T ) into hexone is
decreased by (1) increasing the length of the side chain for the methyl- n-alkyl series,
(2) increasing the branching of the side chain for the methyl- (n-, see-, and tert-)
butyl series, and (3) increasing the symmetry for the seven carbon atom series. These
results can be qualitatively explained by the effect of the decreased basicity of the
carbonyl oxygen as the alkyl side chain is lengthened, and by steric effects in branched
alpha carbon atoms. Khalkin ~.224 found that the distribution coefficient for the ex-
traction of Pu(IY) from 5.0 M HN03 was 11.5 by diethyl ether, and this was the highest
—
among a number of oxygen containing compounds, Pu(IV) was extracted as H2Pu(N03)6
236
at this acidity. Kooi found that for extraction of Pu(IV) from 8 &f HN03 the ex-
traction decreased in the order dibutyl carbitol (DBC) > diethyl ether (DEE) > hexone,
while for Pu(VI) the order was DBC > hexone > DEE. Branica and Bona 54 found that
U(VI) and Th extract at a lower HN03
-—
concentration with several cyclic ethers (e. g.
TABLE IV-23. Distribution Co- tetrahydropyran) than with diethyl ether or
efficients
Various
for Pu(IV) Extracted by
Ketones from 3.2 ~ HN03.245
hexone, and these results are presumably
applicable to Pu also.
Ketone
Methyl -n-p ropyl
Distribution
coefficient
10
A number of other process applications
of this class of extractants are worth mention-
Methyl-n-but yl 2.2
ing at this point. ~, f3! - dibutoxydiethylether
Methylisobut
Methyl-t-butyl
yl 1.6
0.12
(“Butex”
tractants,
) has been used as one of the ex-
along with TBP in a two- solvent
Methyl- n-amyl
Methyl-n-hexyl
0.62
0.22
process for purification of Pu and recovery
of U at the Windscale power reactor facility.
450,188
Di-n-propyl 0.12
The quoted advantages over hexone are (1)
Ethyl- n-butyl 0.23
sufficient
centrations
resistance
of HN03
to attack
to permit
by high con-
use of the
acid as a salting agent, and (2) ‘superior
separation factors of Pu from U. TBP is used as the second extractant because it gives
superior decontamination of the Pu from Ru.
Vdovenko and Kovalskaya
411
used a mixture of dibutyl ether and carbon tetra-
chloride in a Redo-type process with satisfactory results.
Dibutoxytetraethylene glycol (’ ‘pentaether” ) has been used as an extractant,
180
along with a 507’0 pentaether - 5O~o dibut yl ether mixture.
28
Sidda11377, 378
has pioneered the use of N, N disubstituted amides as extractants
for tetra- and hexavalent actinides. The carbonyl oxygen in these compounds has en-
hanced basicity because of the presence of the arnido nitrogen, and therefore should be
analogous to the neutral organo-phosphorous compounds in extraction properties.
Typical resdts for a number of elements and amides are shown in Fig. 34 and Table
IV-24. He found that U(VI) behaved similarly to the phosphorous compounds (e. g.
TBP) in that the extracted complex involves two amide molecules. However, the
quadrivalent species (Pu, Th, etc., ) are extracted with more than two amides per
63