THE RADIOCHEMISTRY OF PLUTONIUM - Sciencemadness.org

D
103 ~
,.2 _
10
I
H
,0-1 ~
/
P
/
Pu(m)
/pU(m)
j’ >U(m)
Pu (m)
AQUEOUS I-& CON:ENTR:TION ([j)
Fig. 8. Extraction of U and Pub
TBP in CC14 from HC1 solutions .24 $3070
essentially unextractable. Larsen and
Seils249 measured the extraction of U
and Pu into 30% TEIP in CC14 (Fig. 8),
and used this system as the basis of an
analytical procedure for these elements
(Procedure 15, Sect. VIII). Both Pu(IV)
and Pu(VI) extract better at all acidities
than U(IV) and “U(VI). The quadrivalent
actinides have higher, distribution co-
efficients than the hexavalent above 5-6
~ HC1, while the reverse is true at
lower acidities. These authors report a
distribution coefficient of about 10 -3 for
Pu(III) and 10-4 for Am(III) in 8 ~ HC1
under the same conditions. The value
for Am is considered more reliable be-
cause of possible partial oxidation of
the Pu(III) to Pu(IV). HC1 is much less
extractable than HN03 into TBP. Larsen
and Seils report D = 0.01 at 6 M HC1 and
—
0.12 at 8&l HC1 into 3070 TBP in
CC14.2’4’
Solovkin et al. 390 found that the
extraction of Pu(IV) into 1.1 &l (3070)
TBP in CC14 from perchloric acid was
appreciable. The distribution co-
efficients varied from 0.0045 at 0.4 M .
HC104 to 0.9 at 6.4 ~ HC104. The ex-
tracted complex was determined to be
di-solvated by TBP dilution experiments.
Pu(IV) and Pu(VI) extract well
into TBP from trichloro - and trifluoroacetic acids. 183 The distribution coefficients
decrease with increasing acidity, rather than the usual increase. The distribution co-
efficients for both Pu(IV) and Pu(VI) are about 4 to 5 times as great for CC13COOH as
for CF3COOH at low acid concentrations. For extraction of Pu(IV) into 30~0 TBP in
Amsco- 125 (a kerosene type diluent) f> m an initial concentration of 0.5 M CC13COOH,
—
D = 21; for Pu(VI), D = 4.
The effect of addition of sulfuric acid and phosphoric acid to l%(~) or Pu(VI) –
nitric acid — TE3P systems is invariably to lower the distribution coefficient
438, 440>437
sulfuric439
– phosphoric. This effect is presumably due to the formation of unextractable
sulfate and phosphate complexes of Pu. The effect is more pronounced in Pu(IV) than in
Pu(VI), and at lower nitric acid concentrations. For example, making the aqueous phase
0.08 M in H2S04 lowered D for Pu(IY) from 16 to 9.5 in 4 JYJHN03; in 2 ~ HN03 the
437
corresponding decrease was from 9 to 1.4. On the other hand the lowering of D for
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