Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 50 (2017)

On-line solvent extraction of Re with a rapid solvent extraction apparatus
coupled to the GARIS gas-jet system
Y. Komori,*1 H. Haba,*1 K. Ooe,*2 D. Kaji,*1 Y. Kasamatsu,*3 H. Kikunaga,*4 A. Mitsukai,*5 K. Morimoto,*1 R. Motoyama,*2J. P. Omtvedt,*6 Z. Qin,*7 D. Sato,*2 N. Sato,*1 Y. Shigekawa,*3 T. Tanaka,*1 A. Toyoshima,*5 K. Tsukada,*5 Y. Wang,*7K. Watanabe,*1 S. Wulff,*6 S. Yamaki,*1 S. Yano,*1 and Y. Yasuda*3
To enable aqueous chemistry studies of Sg (atomicnumber Z = 106) and Bh (Z = 107), we have beendeveloping a continuous rapid solvent extraction apparatus
coupled to the GARIS gas-jet transport system.1) Thisapparatus consists of a continuous dissolution apparatus
called the Membrane DeGasser (MDG)2), a Flow Solvent
Extractor (FSE), and liquid scintillation detectors for theĮ6)-spectrometry. The FSE consists of a Teflon capillary(i.d. = 0.5 mm) and a phase separator. In our previousstudy,1) we investigated the performances of the MDG andFSE using lighter homologs of Bh, 92,94mTc (T1/2 = 4.25, 293min) and 181Re (T1/2 = 19.9 h), produced in the natMo(d,xn)
and natW(d,xn) reactions, respectively, at the AVF cyclotron.
In this work, we coupled the MDG and FSE to the GARIS
gas-jet system and performed on-line solvent extraction ofthe 174,176Re (T1/2 = 2.4, 5.3 min) produced in thenatGd(23Na,xn) reactions.
The natGd2O3 target with a thickness of 349 g/cm2 was
prepared by electrodeposition onto a 3-m Ti foil. The23Na7+ ion beam was extracted from RILAC. The beamenergy was 124.3 MeV at the middle of the target, and thetypical beam intensity was 1.6 particle A. The nuclear
reaction products after preseparation with GARIS wereguided into a gas-jet chamber (100-mm i.d.×20-mm depth)
through a 2.5-m Mylar window. The products were thentransported to the MDG, which was placed in a chemistrylaboratory through a Teflon capillary (2.0-mm i.d. × 10-mlength) by He carrier gas at a flow rate of 1.5 L/min with KClaerosols. In the MDG, they were continuously dissolved in
0.5 M HNO3 at 1 mL/min. The effluents from the MDG weremixed with 1 mL/min of tri-n-octylamine (TOA) in toluenein the Teflon capillary of the FSE. After the phase separation,
both aqueous and organic phases from the FSE wereVXEMHFWHG WR Ȗ-ray spectrometry with a Ge detector todetermine the distribution ratios (D) in the solvent extraction.
We measured the D values of 174,176Re by varying thecapillary length of the FSE from 30 cm to 100 cm to change
the extraction time. We also varied the concentration of TOA
from 0.005 M to 0.1 M to determine the applicable D range
using the 40-cm capillary of the FSE. These D values werecompared with those in equilibrium obtained in the off-line
batch extractions with 181Re. The chemical yields (C.Y.) of174,176
Re were determined as C.Y. = ([A]org. +[A]aq.)×100/[A]fil., where [A]org. and [A]aq. indicate theradioactivities in the organic and aqueous phases,respectively, and [A]fil. is the radioactivity in the aerosols
collected on the glass fiber filter in the chemistry laboratory.
Figure 1 shows the variation of the D values of 174,176Re as
a function of the capillary length. The dashed line indicatesthe D value of 181Re in equilibrium obtained in the batch
extraction. We found that the extraction equilibrium of174,176
Re in 0.5 M HNO3 - 0.01 M TOA in toluene can beattained with a 0.5-mm i.d. × 30-cm capillary at 1 mL/minfor both aqueous and organic solutions. However, for TOA
concentrations   0 it was found that the 40-cm
capillary was too short to reach the extraction equilibrium.
When using the 100-cm capillary of the FSE, the D values of174,176
Re were consistent with those in equilibrium in thewide range of D = 0.3±20 in TOA concentrations of 0.005±0.1 M. The average chemical yields are 71 ± 15% for 174Re
and 79 ± 18% for 176Re. Very recently, we performed
solvent extraction with the short-lived 170Re (T1/2 = 9.2 s)
produced in the 152Gd(23Na,5n) reaction with the GARIS
gas-jet + MDG and FSE system as a model experiment for266
Bh (T1/2 = 10.3 s).3) The result of this experiment is underanalysis.
100.5 M HNO 3

䠆1References

RIKEN Nishina Center
Graduate school of Sci. and Technol., Niigata Univ.
䠆3
Graduate school of Sci., Osaka Univ.
䠆4ELPH, Tohoku Univ.
䠆5JAEA
䠆6Univ. Oslo
䠆7Institute of Modern Physics, Chinese Academy of Sciences
䠆2D174Re MDG-FSE
176Re MDG-FSE
181Re Batch ext.

10.1
020406080
Capillary length / cm100Fig. 1. Variation of the D values of 174,176Re as a functionof capillary length. The concentrations of HNO3 andTOA are 0.5 M and 0.01 M, respectively. The dashedline indicates the D value of 181Re in equilibrium obtainedin the batch extraction.

1) Y. Komori et al., RIKEN Accel. Prog. Rep. 49, 21 (2016).
2) K. Ooe et al., J. Radioanal. Nucl. Chem. 303, 1317 (2015).
3) H. Haba et al., 9th International Conference on Nuclear andRadiochemistry, P2-17, Helsinki, Finland, Aug.–Sep., 2016.

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