Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 47 (2014)

Adsorption behavior of Zr and Hf to TTA-resin in microcolumn fordetermining the forming ability of Rf monofluoride complex
A. Yokoyama,*1,*2 Y. Kitayama,*2,*3 Y. Fukuda,*2,*4A. Toyoshima,*5 K. Tsukada,*5 E. Maeda,*2,*3 H. Kimura,*2,*3T. Taniguchi,*2,*4 S. Ueno,*2,*3 K. Hayashi,*2,*4 H. Kikunaga,*2,*6 M. Murakami,*2,*7 J. Kanaya,*2 M. Huang,*2 and H. Haba*2

The present study aims to elucidate the relevant chemical
species of Rf by reversed-phase extraction chromatography
with 2-thenoyltrifluoroacetone (TTA) as a stationary phase.
Because TTA has been suggested to extract quadrivalent
metallic ions, the distribution ratios of the system may makeit possible to determine the specific complex-formation
constant of Rf. We have so far performed several
experiments for the chemical systems with Zr and Hf ions,but failed to find an experimental condition appropriate formeasuring the adsorption of Rf.1,2)
In order to optimize an appropriate experimental
condition for Rf, in the present study, the equilibration timeand distribution ratios for extraction have been measured bybatch method experiments with carrier-free radiotracers ofZr and Hf on TTA-resin in the 1.0×10-4 －1.0×10-3 M
HF/1.0×10-2 M HNO3 solutions. An online experiment has
been also performed for investigating the reversed-phase
chromatographic behaviors of Zr and Hf on the TTA resinwith Automated Rapid Chemistry Apparatus (ARCA)3) tosimulate the Rf experiments.
The radioisotopes of 88Zr (t1/2 = 83.4 d) and 175Hf (t1/2 =70.0 d) used in the batch experiments were produced by the89Y(p, 2n) and 175Lu(p, n) reactions, respectively, at theRIKEN K70 AVF Cyclotron. The short-lived 85Zr and 169Hf
isotopes were also produced by the 18O-induced reaction
with the natGe and natGd targets, respectively, for the on-lineexperiments. The TTA-resin was simultaneously producedby mixing the CHP20/P20 resin with a TTA-octanol
solution of 50 or 30 wt.%, which includes 50 or 20 wt.% ofTTA in n-octanol, respectively. The prepared TTA-resin
was used for the batch experiments, as well as for theon-line reversed-phase extraction chromatography. The
details of the procedures can be found elsewhere.2)
In the batch experiments, the D value of 50 wt.% resin
was found to be higher than that of the other resin, while thetime for chemical equilibration of the former is almost thesame as that of the other. The elution curves of Zr and Hf ata flow rate of 0.15 mL/min in the range 1.0×10-4－1.0×10-3
M of HF concentration on the former resin are shown in Fig.
1; the peaks of the curves are clearly visible in the figure for*1

Institute of Science and Engineering, Kanazawa University
RIKEN Nishina Center*3
Graduate School of Natural Science and Technology, Kanazawa
University*4
College of Science and Engineering, Kanazawa University*5
Advanced Science Research Center, Japan Atomic Energy Agency*6
Research Center for Electron Photon Science, Tohoku University*7
Faculty of Science, Niigata University*2

all the conditions of HF concentration.
The D values for the on-line experiments are evaluatedfrom the elution curves by using the following equation, D= Vp/m [mL/g], where Vp is the peak volume of an elution
curve, and m is the resin weight in a microcolumn. The D
values of Zr tend to be higher than those of Hf in the on-lineexperiments, although, based on the batch experiments, theD value of Hf should be higher than that of Zr at thechemical equilibrium. For instance, in Fig.1(a) the D valueof Zr was found to be higher than that of Hf by a factor of1.2, although in the batch experiments the D value of Zr
was found lower than that of Hf by a factor of 2.8. Theseresults in the on-line experiments show that the chemical
equilibrium time of Zr is shorter than that of Hf, which
agrees with the results of the present batch experiments
measured as a function of shaking time. The kinetic
behavior observed here should be clarified in order toperform the Rf experiment in the expected project.

Fig. 1. Elution curves of Zr and Hf against the HF concentration,(a) 1.0×10-4 M, (b) 6.0×10-4 M, (c) 1.0×10-3 M, in the HF/0.010-M
HNO3 solution, at a flow rate of 0.15 mL/min. The radioactivity
values in the figure represent the values relative to the total eluted
radioactivity. Solid lines are curves fitted to a theoretical equation
derived by Glückauf model4).

References

1) M. Araki,et al.: RIKEN Accel. Prog. Rep. 43, 271 (2010).
2) A. Yokoyama,et al.: RIKEN Accel. Prog. Rep. 46, 242 (2012).
3) Y. Nagame et al.: Radiochim. Acta, 93, 519 (2005).
4) E. Glückauf: Trans Faraday Soc. 51, 34 (1955).

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