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Sugiura, Yuki; Ishidera, Takamitsu; Tachi, Yukio
Applied Clay Science, 200, p.105910_1 - 105910_10, 2021/01
Times Cited Count：16 Percentile：77.02(Chemistry, Physical)Iida, Yoshihisa; Yamaguchi, Tetsuji; Tanaka, Tadao; Hemmi, Ko
Journal of Nuclear Science and Technology, 53(10), p.1573 - 1584, 2016/10
Times Cited Count：15 Percentile：79.54(Nuclear Science & Technology)The sorption behavior of thorium (Th) onto granitic rock and its major constituent were investigated by batch sorption experiments. Experiments were carried out under variable pH and carbonate concentrations. Distribution coefficients decreased with increased carbonate concentrations and showed the minimal value at pH 9-10. This sorption tendency was likely due to forming the hydroxide-carbonate complexes of Th in the solutions. The order of sorbability for Th was mica 
feldspar quartz = granite. The sorption behaviors of Th onto these minerals were analyzed by the triple-layer surface complexation model with the Visual Minteq computer program. The model calculations assuming the inner-sphere surface complexation of Th were able to explain the experimental results reasonably well. It was shown that the sorption behavior of Th onto granite can be explained primarily by the complexation with the surface sites of feldspar.
on Na-montmorillonite studied by time-resolved laser fluorescence spectroscopy and surface complexation modelingSasaki, Takayuki*; Ueda, Kenyo*; Saito, Takumi; Aoyagi, Noboru; Kobayashi, Taishi*; Takagi, Ikuji*; Kimura, Takaumi; Tachi, Yukio
Journal of Nuclear Science and Technology, 53(4), p.592 - 601, 2016/04
Times Cited Count：15 Percentile：75.86(Nuclear Science & Technology)The influences of pH and the concentrations of Eu and NaNO
on the sorption of Eu to Na-montmorillonite were investigated through batch sorption measurements and time-resolved laser fluorescence spectroscopy (TRLFS). The pH had a little effect on the distribution coefficients (Kd) in 0.01 M NaNO, whereas the Kd strongly depended on pH at 1 M NaNO. A cation exchange model combined with a one-site non-electrostatic surface complexation model was successfully applied to the measured Kd. The TRLFS spectra of Eu sorbed were processed by parallel factor analysis (PARAFAC), which corresponded to one outer-sphere (factor A) and two inner-sphere (factor B and C) complexes. It turned out that factors A and B correspond to Eu sorbed by ion exchange sites and inner-sphere complexation with hydroxyl groups of the edge faces, respectively. Factor C became dominant at relatively high pH and ionic strength and likely correspond to the precipitation of Eu(OH) on the surface.
Ikeda, Takashi; Suzuki, Shinichi; Yaita, Tsuyoshi
Journal of Physical Chemistry A, 119(30), p.8369 - 8375, 2015/07
Times Cited Count：24 Percentile：66.48(Chemistry, Physical)Adsorption states of alkali metal ions in three kinds of 2:1 type clay minerals are systematically investigated via first-principles-based metadynamics. Our reconstructed free energy surfaces in a two dimensional space of coordination numbers specifically employed as collective variables for describing the interlayer cations show that an inner-sphere (IS) complex is preferentially formed for Cs
in the 2:1 type trioctahedral clay minerals with saponitelike compositions, where lighter alkali ions show a tendency to form an outer-sphere one instead. The strong preference for an IS complex observed for Cs is found to result partially from the capability of recognizing selectively Cs ions at basal O atoms with the Lewis basicity significantly enhanced by the isomorphic substitution in tetrahedral sheets.
Matsunaga, Takeshi; Nagao, Seiya*; Ueno, Takashi; Takeda, Seiji; Amano, Hikaru; Tkachenko, Y.*
Applied Geochemistry, 19(10), p.1581 - 1599, 2004/10
Times Cited Count：38 Percentile：56.07(Geochemistry & Geophysics)The association of dissolved 
Sr, 
Pu and 
Am with natural colloids was investigated in surface waters in the Chernobyl nuclear accident area by means of ultrafiltration. Results suggest that Pu and Am isotopes were preferentially associated with dissolved humic substances (HS) of high molecular size. A model calculation of the complexation of Pu and Am with HS also supported the above. This study has expanded our understanding of the general role of natural organic colloids in dictating the chemical form of actinides in the surface aquatic environment.
Yamazawa, Hiromi;
J.Appl.Meteorol., 28(9), p.996 - 1001, 1989/09
no abstracts in English
Ikeda, Takashi
no journal, ,
no abstracts in English
Sugiura, Yuki; Ishidera, Takamitsu; Tachi, Yukio
no journal, ,
