THE RADIOCHEMISTRY OF PLUTONIUM - Sciencemadness.org

oxygen in the ratio 1:3. If an excess of peroxide is used in the precipitation, the
ratio may be lower. The extra peroxide also serves to hold the sheets together.
Precipitation of plutonium peroxide has been used as a purification step for Pu
from most other cations 72, 158, 329, 425 and as a step in the preparation of high purity
Pu compounds and solutions.
329
This precipitation has been used to separate Pu from
Am, the Am remaining in the supernatant solution,
72
and to separate
277
Pu and U.
~
the latter procedure the Pu was oxidized to Pu(VI) by potassium bromate which served
as a holding oxidant, and uranyl peroxide precipitated. Separation factors of 2-4
were obtained.
Oxalates. Precipitation of plutonium oxalate from dilute acidic solution
has been used as a concentration step before conversion to oxide or metal. 265 The
separation factors from other elements are not so great in some cases as in the
peroxide precipitation procedure
431, 141
(Table W- 14), but the precipitate is easy to
filter and work with. The se compounds undergo decomposition by the action of their
134, 389, 216
own alpha radioactivity. The oxalate is decomposed into carbonate and CO,
and the CO may reduce either Pu(VI) or Pu(IY).
Other compounds. The precipitation of plutonium (IV) sulfate tetrahydrate
has been used to prepare a high purity Pu compotmd for use as a gravimetric standard
for Pu.424 Starting with a grossly impure solution, a product of 99. 98~, purity was
obtained after five successive recrystallization. This compound is suitably stable as
a gravimetric standard at least for 18-months, 448
Dicesium plutonium (IV) hexachoride has also been proposed as a primary
gravimetric standard.27g The compound can be prepared by precipitation from an 8
~ HC1 solution of Pu(lY ) by addition of C sC1 in HC1.
D. 2 Solvent Extraction Methods
The large-scale processing of reactor targets is largely done by liquid-liquid
extraction. This is so because of a combination of desirable properties of this
method; for example, great specificity for U and Pu, easy adaptability to remote
handling facilities, etc. These advantages are easily carried over to laboratory
separations where specificity and ease of handling are equally important.
A very great deal of research on liquid-liquid extraction systems for Pu has
been carried out in the development of large-scale processes, and a large portion of
the solvent extraction data reported in this section was taken under the spur of the
seemingly never-ending quest for more specific extractants, better radiation stability,
and the like. The basic data on the extractive properties of a given solvent are, of
course, equally applicable in the laboratory or industrial situation,
The general principles of solvent extraction have been put forth i’n the book by
Morrison and Freiser,
292
and in a comprehensive review by Marcus.
267
The solvent
extraction data for Pu have been thoroughly reviewed by Smith. 388 Carleson77 has
written a good general survey of the processing chemistry of nuclear fuel for Pu, while
450
a recent symposium contained much of interest concerning the newer extraction
systems.
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