Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 52 (2019)

Adsorption experiments of 88 Y and 143 Pm on in HNO3
T. Yokokita,∗1 S. Yano,∗1 Y. Komori,∗1 and H. Haba∗1
Seventeen elements of Sc, Y, and 15 lanthanides arecalled as rare earth elements (REEs). REEs are used
in a wide range of applications such as semiconductors,catalysis, lasers, magnets, and neutron absorbents.1) It
is diﬃcult to purify them due to their very similar chemical properties. Therefore, simple and eﬀective mutualseparation methods are needed to obtain pure materials
for the industry.
So far, many extractants have been developed, andsome extractants are commercially available. However,
the adsorption behavior of REEs on those resins were
only reported for some elements in some inorganic solutions. A systematic study of the adsorption behaviorof many elements will be useful for the development ofseparation and puriﬁcation technology. In this work, todevelop the separation methods of REEs, we studied theadsorption behavior of Y and Pm using 18 commerciallyavailable resins.
88Y and 143 Pm were produced in the nat Sr(d, xn)88 Y
and nat Pr(α, xn)143 Pm reactions using the K70 AVF cyclotron at RIKEN and were separated from the target materials using LN resin. In the adsorption experiments, the resins (Actinide, CU, DGA (normal),
DGA (branched), LN, LN2, Muromac 1 × 8, Muromac
50 W × 8, Pb, RE, Sr, TBP, TK 100, TK 101, TK 400,TRU, UTEVA, and ZR resins) were added in 1 mL ofHNO3 containing 88 Y or 143 Pm in a PP tube, and themixture was shaken for 4 h using a mixer. After that,the resin was removed by centrifugation. Subsequently,
the ﬁltrate was pipetted into another tube and weighed
and then subjected to γ-ray spectrometry using a Ge detector. Finally, the HNO3 concentrations of the aqueous
phases were determined by titration with a standardized
NaOH solution. In all the adsorption experiments, control experiments without the resin were performed. The
Kd values were determined from the following equation:
Kd = Ar Vs /As wr = (Ac − As )Vs /As wa(1)

where Ar , As , and Ac are the radioactivities of the resin,the solution, and the control solution, respectively. Vs isFig. 1. The Kd values of Y and Pm with LN resin as a function of HNO3 concentration.
∗1RIKEN Nishina CenterFig. 2. The Kd values of Y and Pm with TRU resin as afunction of HNO3 concentration.

the volume (mL) of the solution, and wa is the mass (g)of the dry resin.
We investigated the Kd values of Y and Pm as functions of HNO3 concentration. The Kd values of Y andPm were low (≤20 mL g−1 ) and constant when we used
CU, Muromac 1 × 8, Pb, Sr, TBP, TK 101, TK 400,UTEVA, and ZR resins in 0.1–13 M HNO3 . It was foundthat these resins are not suitable for the separation of Yand Pm in HNO3 .
Using DGA (branched) and Muromac 50 W×8 resins,
Y and Pm were adsorbed on the resins in some HNO3
concentrations, and the Kd values of Y agreed with thoseof Pm. Therefore, these resins are not useful for theseparation of Y and Pm from each other.
When Actinide and DGA (normal) resins were used,
the Kd values of Y and Pm were ≥102 mL g−1 , and thevalues were diﬀerent from each other. Y and Pm can beseparated using these resins. However, those Kd values
were ≥102 mL g−1 in 0.1–13 M HNO3 , and both Y andPm were adsorbed on the resins. The Y and Pm species
adsorbed on these resins can be stripped by using a large
volume of eluents, and this separation method requires
a long time. It is concluded that Actinide and DGA(normal) resins are not suitable for the separation of Yand Pm.
Figure 1 shows the dependences of the Kd values of Yand Pm on the HNO3 concentration in the adsorption
experiment using LN resin. When LN resin is used, theKd values of Y are higher than those of Pm in a high
HNO3 concentration range. The same behavior was observed using LN2 and TK 100 resins. Figure 2 shows theHNO3 concentration dependences of the Kd values of Yand Pm on the TRU resin. The Kd values of Y are lower
than those of Pm when TRU resin is used. The samebehavior was obtained with RE resin. It is suggested
that these resins are useful for the separation of Y andPm.
In the future, we will perform adsorption experiments
using other REE elements and discuss about good separation conditions for REEs.
Reference1) B. Swain, E. O. Otu, Sep. Purif. Technol. 83, 82 (2011).

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