SEQUENTIAL SEPARATION PROCEDURES
Pu, Np, U
t
554
555
Elute from column
successively
Contains A]
| Extract with Isopropyl] Ether |
then La(OH);,
ppt traces U,
Np. Add back
}
Pot.
Extract ppt. with 3N NaOH + NH.OH, HCI]
t
Solution
Add HI
Insoluble
| Ppt Le
"pSolution
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Contains Zr, (Ti), (Th), and
rare earths. Separate on
cation exchange column
for simultaneous determi-
On Column
report a very comprehensive method
Fraction thru column
(1974)
Pass in 9N HC1 through
anion exchange column
S411 et al.
nation of the alpha-emitting nuclides, Ra through Cf, in soil.
After a fusion,
the elements are precipitated on BaSO,.
An extraction of the elements, Th
through Pu, into Aliquat-336 is made from an acidic aluminum nitrate solution
which is then treated to sequentially strip Th through Pu.
Americium, Cm, and
Cf are extracted into Aliquat-336 from acid deficient aluminum nitrate and
1
~-Supernatant ___{ Fuming 6N HNO, soln.
NHsy(g)
Buckley (1969) compiled a manual which contains several procedures for separating various combinations of the actinides, cracer-free, by a combination of
precipitation and ion exchange steps, followed by gross alpha ccunting or
alpha specroscopy for identification.
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HNO,, HClO, HF:
Ion exchange separations have especially been of great value in the separation
and identification of the transcurium elements.
Thompson et al. (1954) employed
Dowex-50 columns plus eluants of ammonium lactate and ammonium citrate.
Choppin et al. (1956) employed ammonium alpha-hydroxyisobutyrate as a superior
eluant for Am, Cm, Bk, Cf, E, Fm, and Mv mixtures from Dowex-50 columns.
Such
separations might be considered the ideal because a number of elements are
efficiently separated in one continuous operation.
However, usuaily the
sample matrix elements will preclude the use of the classical procedures which
also involve the use of rather expensive columns.
t
Insoluble f
24lam, 242cm, and !"/Pm in fallout with applicability to other sample lines
but the method had low tolerance for rare earths. Nash (1964) had a procedure
for the separation of over 30 elements using a Dowex-50 cation exchange column
and ammonium alpha~hydroxyisobutyrate at various concentrations and pH.
The
procedures by Wong et al. (1970), Figure 4, shows the sequential steps used
for isolating Pu and Am from large seawater samples.
Since there are a
wide number of such sequential procedures, further discussion is Limited to
One alternative is to dissolve the sample prior to
the transuranium elements.
adding carriers and/or tracers and use appropriate sized aliquant portions for
each element of interest.
Ref: JINC 2 p 224 (1956)
i
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Activity and carriers with inorganic impurities Ba. , Sr, Mo, Ag, Y, Eu, Sm, Nd, Pr, Ce, La,
Zr, Cd, U, Np, Pu , Cs, Rb, Ru, (Fe), (Ca), (Ti), (Mg), (AD, (Si), (Th) fuse with KOH, KNO,
and K:COQ,. Extract with water.
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1 CC Lextraction]
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FIGURE 3 CROUCH AND COOK'S SEPARATION SCHEME AS APPLICABLE TO TRANSURANIUMS
Often it is required to analyze more than one radionuclide from a single
sample.
In order to achieve maximum results from scarce sample material and
optimize analytical sensitivity as well as distribute expensive sample preparation costs over several elements, a sequential separation procedure is used.
A typical multipurpose 26-element sequential separation scheme, suitable for
many radioactive elements including Pu, Np, and U but with no provision for Am
or Cm, is that of Crouch and Cook (1956).
That portion applicable to Pu, Np,
and U ig shown in Figure 3.
It is quite similar to later procedures and the
authors pointed out that certain parts of the procedure required experienced
and special manipulation for successful recoveries.
The most common transuranic
sequential separation procedures in use have been for Pu and Am.
A survey of
Pu and Am procedures is given by Wessman et al. (1974).
However, even more
extensive sequential separation schemes have been employed successfully at
this laboratory for many years on up to 22 elements, although they were limited
to certain sample types. Hunt et al. (1968) reported on a scheme for analyzing