Ⅰ. HIGHLIGHTS OF THE YEARRIKEN Accel. Prog. Rep. 49 (2016)

Developmentofofaarapid
rapidsolvent
solvent extraction
extraction apparatus
Development
apparatusfor
forthetheaqueousaqueouschemistry of thechemistry
the heaviest
heaviestelements
elements
Y. Komori,*1 H. Haba,*1 K. Ooe,*2 A. Toyoshima,*3 A. Mitsukai,*3 M. Murakami,*1,*2 D. Sato,*2 R. Motoyama,*2 S. Yano,*1K. Watanabe,*1 A. Sakaguchi,*4 J. Inagaki,*4 H. Kikunaga,*5 and J. P. Omtvedt*6were then subjected to the γ-ray spectrometry to determine
the distribution ratios (D). We measured the D values of Tc
and Re by varying the capillary length from 5 cm to 100 cm
to change the extraction time. We also varied aconcentration of TOA from 0.005 M to 0.1 M to evaluate anapplicable D range with the FSE. These D values werecompared with those in the batch extraction that wereobtained by 3-min shaking.
The dissolution efficiencies of 90mNb, 90gNb, and 178aTa
with the MDG were 56 ± 2, 88 ± 6, and 82 ± 7%,respectively. The efficiency of the short-lived 90mNb issmaller than those of the long-lived 90gNb and 178aTa. In theonline solvent extraction with the MDG-FSE, a variation of
the D values of Tc and Re is shown in Fig. 1 as a functionof the capillary length. The extraction equilibrium of Tc andRe was attained with the 40-cm capillary. The time required
for the solutions to pass through the 40-cm capillary is
calculated as 2.4 s, which is sufficiently short to perform thesolvent extraction with 265Sga,b (T1/2 = 8.5 s, 14.4 s)4) and266
Bh (T1/2 = 10.7 s).5) We also found that the D values of Tc
and Re increase with increasing the TOA concentration. The
D values with the MDG-FSE were consistent with those in
the batch extraction except for Tc at a high TOA
concentration of > 0.05 M, where the D values obtained forTc with the MDG-FSE were slightly smaller than those in
the batch extraction. The reason of this discrepancy is underconsideration.
10D

To realize the aqueous chemistry studies of Sg (Z = 106)and heavier elements, we are developing a continuous andrapid solvent extraction apparatus coupled with the GARIS
gas-jet system.1) This apparatus consists of a continuous
dissolution apparatus called as Membrane DeGasser (MDG),
Flow Solvent Extractor (FSE), and liquid scintillation
detectors. In this work, we developed the MDG and FSE,
and conducted online solvent extraction of Tc and Re as
homologs of element 107, Bh.
We modified the MDG developed by a research group ofUniv. Oslo and JAEA.2) Major modifications were to reducea dead volume of the apparatus from 90 µL to 23 µL and tosimplify the structure of the gas/solution-mixing unit todissolve shorter-lived nuclides with higher efficiencies at alower flow rate of 1 mL/min. Further, we fabricated theFSE that consisted of a Teflon capillary and a phaseseparator by referring to a well-known flow injection
analysis technique.3) The inner diameter of the capillary is
0.5 mm. We can easily change the extraction time byvarying the capillary length. In the phase separator, organicand aqueous phases are separated from each other with aPTFE membrane filter (ADVANTEC T300A013A) byapplying pressure on the outlet of the capillary of theaqueous phase.
We investigated the performance of the MDG using theAVF cyclotron at RIKEN. Short-lived 90m,gNb (T1/2 = 18.8 s,14.6 h) and 178aTa (T1/2 = 2.36 h) were simultaneously
produced in the natZr(d,xn) and natHf(d,xn) reactions,respectively. The reaction products were transported by theHe/KCl gas-jet system to the MDG in the chemistrylaboratory. The reaction products were dissolved with 1 M
HF at a flow rate of 1 mL/min. The solution from the MDG
was collected for 1 min and was then subjected to γ-ray
spectrometry with a Ge detector. The dissolution
efficiencies were determined by comparing the radioactivity
in the solution with that of the direct catch on a glass fiber
filter (ADVANTEC GB-100R). Next, we coupled the MDG
and the FSE and performed online solvent extraction of Tc
and Re. 92,94mTc (T1/2 = 4.25, 293 min) and 181Re (T1/2 = 20h) produced simultaneously in the natMo(d,xn) andnatW(d,xn) reactions, respectively, were transported by thegas-jet to the MDG. They were continuously dissolved with0.5 M and 1 M HNO3, and they were extracted with theFSE into an organic phase of tri-n-octylamine (TOA) intoluene. Both aqueous and organic phases from the FSE

1 M HNO 392,94gTc MDG-FSE
181Re MDG-FSE
94gTc Batch ext.
181Re Batch ext.

10.1
020406080
Capillary length [cm]100Fig. 1. Variation of the D values of Tc and Re as afunction of the capillary length. The concentrations ofHNO3 and TOA are 1 M and 0.01 M, respectively.
0References

12Time / s
34561) H. Haba et al.: Chem. Lett. 38, 426 (2009).
2) K. Ooe et al.: J. Radioanal. Nucl. Chem. 303, 1317 (2015).
3) S. Motomizu: J. Flow Injection Anal. 5, 71 (1988).
4) H. Haba et al.: Phys. Rev. C 85, 024611 (2012).
5) H. Haba et al.: Pacifichem 2015, Honolulu, Hawaii, U.S.A.,
Dec. INOR 1578, 2015.

RIKEN Nishina Center＊2
Graduate school of Sci. and Technol., Niigata Univ.
＊3JAEA＊4Univ. Tsukuba＊5
ELPH, Tohoku Univ.
＊6Univ. Oslo＊1- 21 -95m
183R