Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 49 (2016)

Extractionbehaviors
behaviorsof
ofchloride
chloride complexes
complexes ofExtractionof Nb
Nb andandTa
Tawithwithtriisooctyl
triisooctylamineof dubnium
dubnium(Db)(Db)
for chemicalchemical experimentexperiment ofaminefor
R. Motoyama,䠆1,䠆2 K. Ooe,䠆1 M. Murakami,䠆1 H. Haba,䠆2 S. Goto,䠆1 and H. Kudo䠆3It has been reported that the anion-exchange behavior of
the 105th element, Db, in HF/HNO3 solution is similar tothat of Nb rather than Ta.1) In our laboratory, the extraction
behaviors of fluoride complexes of Nb and Ta with tributyl
phosphate (TBP)2) and Aliquat 3363) have been investigated.
The extraction yield of Ta is greater than that of Nb in thesesystems. For the extraction of Db with TBP from 1.0 M HF,
the behavior of Db was significantly different from that ofTa.4) To clarify the similarity of the extraction behavior
between Db and Nb, systems where the extraction yield ofNb is greater than that of Ta should be studied. We
investigated the extraction behaviors of Nb and Ta fromHCl with triisooctyl amine (TiOA) on a tracer scale. It has
been reported that the extraction yield of Nb is greater thanthat of Ta on a macro scale.5)
Radiotracers, 95gNb (T1/2 = 34.991 d) and 179Ta (T1/2 =1.82 y), were produced from natZr(d,xn) and natHf(d,xn)
reactions, respectively, using the RIKEN AVF cyclotron.
These radiotracers were chemically isolated from the target
materials through an anion-exchange method and preservedin 1 M HF. An appropriate amount of this solution wasevaporated to dryness and preserved in concentrated HCl(stock solution). An aliquot of the stock solution wasevaporated to dryness and dissolved in an appropriate
concentration of HCl. In a 1.5 mL polypropylene tube, 600
μL of 8–10 M HCl containing the tracers was mixed with anequal volume of 0.12 M TiOA in xylene, and the mixture
was shaken for a fixed time. After centrifugation, 420 μL
aliquots of each phase were separated into sample tubes.
The radioactivity of each phase was measured with a Gedetector. We calculated the distribution ratios (D) of 95gNb
and 179Ta using the following equation:of 95gNb are approximately 102 times greater than those of179
Ta. The D values of 179Ta are greater than the values in
the literature, although those of 95gNb are in agreement withthose in the literature. In the course of the investigation, theD values of 179Ta decreased with time lapsed from thepreparation of the stock solution, while those of 95gNb
stayed constant (Fig. 2). The decreasing trend of the Dvalues of 179Ta may be caused by hydrolysis of the Ta
species or an effect of residual fluoride ions in the stocksolution. The preparation methods of the Ta tracer may beconsidered for the study of the extraction behavior of achloride complex of Ta. A detailed investigation isnecessary to solve the problem.
103

Distribution ratio

95g102

179

NbTa

101
100
10-1
10-2
78

910
[HCl]/M

1112Fig. 1. The distribution ratios of 95gNb and 179Ta extracted
into 0.12 M TiOA in xylene as a function of the HClconcentration. Dashed lines indicate the literature values of
Nb and Ta. 5)

Distribution ratio

103

D = (Aorg / Vorg) / (Aaq / Vaq),
where Aorg and Aaq are the radioactivities in organic andaqueous phases, respectively, and Vorg and Vaq are thevolumes of the organic and aqueous phases, respectively.
The extraction kinetics from 10 M HCl into 0.12 M TiOA
in xylene were investigated by changing the shaking timefrom 1 min to 60 min. It was found that the D values of95g
Nb and 179Ta were almost constant in the examined rangeof shaking time. This result shows that the extraction
equilibrium is achieved quickly.
The dependence of the D values of 95gNb and 179Ta
extracted into 0.12 M TiOA in xylene is shown in Fig.1 as afunction of the HCl concentration (8–10 M). The D values

95g102179

NbTa

10110010-1
10-2
10-3050100
150200Elapsed time/day250Fig. 2. Variation of the distribution ratios of 95gNb and 179Tafrom 10 M HCl extracted into 0.12 M TiOA in xylene as afunction of time lapsed from the preparation of the stocksolution.
References

1) Y. Kasamatsu et al., Chem. Lett. 38, 1084 (2009).
2) S. Tsuto et al., RIKEN Accel. Prog Rep. 47, 270 (2014).
3) D. Sato et al., RIKEN Accel. Prog Rep. 47, 271 (2014).
4) M. Murakami et al., RIKEN Accel. Prog Rep. 48, 279 (2015).
5) T. Ishimori et al., Nihon Genshiryoku Gakkaishi 3, 698 (1961).

Graduate School of Science and Technology, Niigata University
RIKEN Nishina Center
䠆3
Faculty of Science, Niigata University
䠆1
䠆2- 238 -