Separation of lanthanides by ion exchange method depends on
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Separation factors have been reported recently for the tripositive trans-
plutonium actinide elements on elution from a cation exchange resin column
with a solution of ammonium a.-hydroxy isobutyrate. 1 Table I is a summary of
the separation factors, a , of the lanthanide elements expressed relative to
0
gadolinium. These data were obtained from elution volumes after subtraction
·of the free column volume. Curium is included in order that the relative
positions of the lanthanides and adtinides may be compared by using the data
in Ref. 1. The probable error in these separation factors is of the order of
five percent.
A Dowex-50 X-12 (400 + mesh) resin bed. 5 em x 0. 2 em was used in a
column of the type previously described. 2 The elution was performed at
87° C at a flow rate of 1. 0 ml/cm2 /min although preliminary experiments
indicate that elution at 25° C does not decrease the separation factors more
than 10 percent. The large separation factors made it necessary to perform
a numbe:r of elutions u:sing various combinations of three to five adjacent
lanthanides. The eluting solutions ranged from 0. 2 ~· in a.-hydroxy isobutyric
acid pH 4. 0 for lutetium=ytterbiu.m=thulium s~parations to 0. 4 ~pH 4. 6 for
neodymium-praseodymium-cerium-lanthanum. The pH necessary to elu:te
an ion in a desired volume was determined for a 0. 4 M soLution of isobutyrate
from a pH vs. drop number curve (Ref.l, Fig. 2) by using the separation fac=
tor relative to curium. In order to minimize pH sensitivity, it was desirable
to use solutions in a ·pH range of 4. 2 to 4. 8. If for a. particular separation
the curve indicated the choice of a 0. 4. ~ solution of pH lower than 4. 2, con=
centrations of 0. 3 M. or 0. 2M were used instead. Since the concentration
of free isobutyrate ion determines the elution volume, the acid constant ex=
pression was used to calculate the pH necessary to give the same isobutyrate
ion concentration as the 0. 4 M - pH combination obtained from the curve. The
value for the Ka at 25° C (10="5. 96 ) could be used in this calculation with satis=
factory results.
plutonium actinide elements on elution from a cation exchange resin column
with a solution of ammonium a.-hydroxy isobutyrate. 1 Table I is a summary of
the separation factors, a , of the lanthanide elements expressed relative to
0
gadolinium. These data were obtained from elution volumes after subtraction
·of the free column volume. Curium is included in order that the relative
positions of the lanthanides and adtinides may be compared by using the data
in Ref. 1. The probable error in these separation factors is of the order of
five percent.
A Dowex-50 X-12 (400 + mesh) resin bed. 5 em x 0. 2 em was used in a
column of the type previously described. 2 The elution was performed at
87° C at a flow rate of 1. 0 ml/cm2 /min although preliminary experiments
indicate that elution at 25° C does not decrease the separation factors more
than 10 percent. The large separation factors made it necessary to perform
a numbe:r of elutions u:sing various combinations of three to five adjacent
lanthanides. The eluting solutions ranged from 0. 2 ~· in a.-hydroxy isobutyric
acid pH 4. 0 for lutetium=ytterbiu.m=thulium s~parations to 0. 4 ~pH 4. 6 for
neodymium-praseodymium-cerium-lanthanum. The pH necessary to elu:te
an ion in a desired volume was determined for a 0. 4 M soLution of isobutyrate
from a pH vs. drop number curve (Ref.l, Fig. 2) by using the separation fac=
tor relative to curium. In order to minimize pH sensitivity, it was desirable
to use solutions in a ·pH range of 4. 2 to 4. 8. If for a. particular separation
the curve indicated the choice of a 0. 4. ~ solution of pH lower than 4. 2, con=
centrations of 0. 3 M. or 0. 2M were used instead. Since the concentration
of free isobutyrate ion determines the elution volume, the acid constant ex=
pression was used to calculate the pH necessary to give the same isobutyrate
ion concentration as the 0. 4 M - pH combination obtained from the curve. The
value for the Ka at 25° C (10="5. 96 ) could be used in this calculation with satis=
factory results.
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Answer:
Explanation:
On the size of hydrated ions
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