Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 50 (2017)

Fundamental study on DFO complexation of Zr :Application to the behavior of geochemical pairs in aquatic environment
J. Inagaki, *1 A. Sakaguchi, *1 H. Haba, *2 Y. Komori, *2 and S. Yano *2

Complexation rate (%)

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solution in the first step of the procedure. Subsequently, inEHLQJ WKHRUHWLFDOO\ WKH VDPH DV WKDW RI WKH FKRQGULWH
the first step, evaporation to dryness was avoided, and thePHWHRULWH+RZHYHU RZLQJWR WKH RQJRLQJGHYHORSPHQWRI
sample solution was carefully treated to prepare the chloride
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realized.
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The amount of hydrolysed Zr on the filter was estimated to
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be 59%, and the absolute amount was 295 pmol. The
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membrane filter in the form of dissolved species and/or
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colloidal material.
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Fig. 1. DFO-Zr complexation rate as a function of stirring time.
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The complexation rate of Zr with DFO is outlined as a
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function of stirring time in Fig. 1. As can be seen, theXVLQJDPHPEUDQHILOWHU SRUHVL]HRIPP DIWHUVWLUULQJ
complexation rate of Zr with DFO increased with time, andIRUPLQ7KH=Uin the filtered solution ZDVGHWHUPLQHG
an equilibrium condition was not established. Moreover, theDQG WKH DPRXQW RI K\GURO\VHG =U RQ WKH ILOWHU ZDV
percent complexation rate was quite low. Here, the ratio
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between Zr and DFO (in moles) was about 20 and the7KH K\GURO\VHG =U ZDV WUDQVIHUUHG WR  P/ RI  0
competitive reaction between OH- and DFO did not seem to1D&O VROXWLRQ FRQWDLQLQJ  Q0 RI VLGHURSKRUH DQG WKHhave been operating. Thus, for future experiments, theUHVXOWLQJ VROXWLRQ ZDV VWLUUHG IRU  K $V DQ DQDORJRXV
concentration of DFO should be increased to study more
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precisely the complexation of Zr with DFO. An additional
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work is definitely needed to clarify the complexation
VXEVDPSOHG DW W        DQG  K DQG WKHbehavior of Zr and Hf.
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*7%3 0HUFN 0LOOLSRUH  7KH =UJUD\ LQWHQVLWLHVReferences
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1) V. M. Goldschmidt, Chem. Soc. 1, 655 (1937).
7KH DPRXQW RI ILOWHUHG =U ZDV FRQVLGHUHG WR UHSUHVHQW WKH2) M. L. Firdaus et al., Nat. Geosci. 4, 227 (2011).
FRQFHQWUDWLRQRIWKH')2=UFRPSOH[HV3) K Schmidt et al., Geochem. Cosmochim. Acta 140, 468 (2014).
7KH FKHPLFDO \LHOG RI =U from the Y foilwas found to4) D. Kraemer et al., Geochem. Cosmochim. Acta 165, 263
be very low, a few percent, in the first experiment. This low(2015).
yield might have been caused by Zr fixation at the bottom5) H. Haba et al., Radiochim. Acta 89, 733 (2001).
       6)
 H.
 Haba  et al., Bull.
 Chem.
  Soc.
  Jpn 6, 698  (2009).
           
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Graduate School of Pure and Applied Sciences, University of Tsukuba
RIKEN Nishina Center- 253 -