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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：12 Percentile：74.37(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.
Nishi, Shusaku*; Miyakawa, Kazuya; Toda, Kanako*; Saito, Takumi*
no journal, ,
In HLW disposal, NOM changes radionuclides behavior. For surface NOM, models that express bonding with metal ions under various conditions have been proposed. To use such models in the safety evaluation of geological disposal, binding reactions between NOM in deep underground and nuclides are evaluated, and features are compared with the NOM in surface. In March 2021, we focused on the fact that NOM fluorescence is extinguished by combining with metal ions, and conducted quenching experiments where europium was added to the deep groundwater containing NOM. Using PARAFAC, a multivariate analysis method, fluorescent NOM components that contribute to binding are identified, and properties and reactivity with europium are discussed. In this presentation, new samples are added for more comprehensive discussions.
Sugiura, Yuki; Ishidera, Takamitsu; Aoyagi, Noboru; Mei, H.; Saito, Takumi*; Tachi, Yukio
no journal, ,
Mei, H.; Aoyagi, Noboru; Saito, Takumi*; Sugiura, Yuki; Ishidera, Takamitsu; Tanaka, Kazuya; Tachi, Yukio
no journal, ,
Saito, Takumi*; Nishi, Shusaku*; Sato, Hayato*; Miyakawa, Kazuya; Amano, Yuki; Beppu, Hikari*
no journal, ,
no abstracts in English
