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Journal Articles

Prediction of stability constants for novel chelates design in minor actinides partitioning over lanthanides using density functional theory calculation

Kaneko, Masashi; Sasaki, Yuji; Wada, Eriko*; Nakase, Masahiko*; Takeshita, Kenji*

Chemistry Letters, 50(10), p.1765 - 1769, 2021/10

https://doi.org/10.1246/cl.210402

Times Cited Count：0 Percentile：0(Chemistry, Multidisciplinary)

Density functional theory calculation is applied to predict the stability constants for Eu $^{3+}$ and Am $^{3+}$ complexes in aqueous solution for molecular modelling of novel separation agents for minor actinides over lanthanides. Logarithm of experimental stability constants correlates with calculated complex formation enthalpies with high reproducibility (R $^{2}$ 0.98). Prediction of stability constants of novel chelates is demonstrated and indicates a potential availability of the derivatives of diethylenetriaminepentaacetic acid type chelate in acidic condition and enhancement of Am $^{3+}$ selectivity over Eu $^{3+}$ .

JAEA Reports

Influence of naturally-occurring heterogeneous complex-forming materials on the migration behavior of actinides in the geosphere (III)

Tochiyama, Osamu*

JNC TJ8400 2000-044, 53 Pages, 2000/02

JNC-TJ8400-2000-044.pdf:1.41MB

To estimate the polyelectrolyte effect and the effect of the heterogeneous composition of humic acids, the complex formation constants of Eu(III) and Ca(II) with Aldrich humic acid and polyacrylic acid were obtained, for Eu(10 $^{-8}$ to 10 $^{-5}$ M) by solvent extraction with TTA and TBP in xylene, for Ca (10 $^{-10}$ M) with TTA and TOPO in cyclohexane and for Ca(10 $^{-4}$ M) by using ion-selective electrode. By defining the apparent formation as $beta_{alpha}$ = [MR $_{m}$ ]/([M][R]), where [R] denotes the concentration of dissociated functional group, [M] and [MR $_{m}$ ] denote the concentration of free and bound metal ion and pcH is defined as-log[H], the values of log $beta_{alpha}$ have been obtained at pcH 4.8 - 5.5 in 0.1 - 1.0M NaClO $_{4}$ and NaCl. Log $beta_{alpha}$ of Eu-humate varied from 5.0 to 9.3 and that of Ca-humate from 2.0 to 3.4..For both humate and polyacrylate, log $beta_{alpha}$ increased with pcH or with the degree of dissociation. The increase in the ionic strength O.1 to 1.0 M decreased the log $beta_{alpha}$ , the decrease in log $beta_{alpha}$ of Eu(III)-humate is 1.6, that of Eu(III), polyacrylate 0.7, that of Ca(II)-humate 1.9 and that of Ca(II)-polyacrylate 1.2. While the increase in the metal ion produced no effect on log $beta_{alpha}$ of polyacrylate, log $beta_{alpha}$ of humate decreased. Depending on the concentration of Eu(III), the coexistence of Ca(II) reduced log $beta_{alpha}$ of humate by 0 to 0.8. The dependence of log $beta_{alpha}$ of humate on the metal ion concentration suggests the coexistence of strong and weak binding sites in the hmnic acid.

JAEA Reports

Thermodynamic Date for Predicting Concentrations of AnO $_{2}$ $^{+}$ and AnO $_{2}$ $^{2+}$ Species in Geologic Environments

Choppin, G. R.*; Bronikowski, M.*; Chen, J.*; Byegard, J.*; Rai, D.*; Yui, Mikazu

JNC TN8400 99-012, 155 Pages, 1999/01

JNC-TN8400-99-012.pdf:5.53MB

This report provides thermodynamic data for predicting concentrations of pentavalent and hexavalent actinide species (AnO $_{2}^{+}$ and AnO $_{2}^{2+}$ ) in geologic environments, and contributes to an integration of the JNC chemical thermodynamic database, JNC-TDB (previously PNC-TDB), for the performance analysis of geological isolation system for high-level radioactive wastes. Thermodynamic data for the formation of complexes or compounds with hydroxide, chloride, fluoride, carbonate, nitrate, sulfate and phosphate are discussed in this report. The estimation of the stability constants by use of the Born equation is included. The Pitzer parameters for AnO $_{2}^{+}$ and AnO $_{2}$ $^{2+}$ , redox potentials and equilibrium constants of redox reactions for actinides are also included.

JAEA Reports

Thermodynamic Date for the Speciation and Solubility of Pd, Pb, Sn, Sb, Nb, and Bi in Aqueous Solution

Lothenbach, B.*; Ochs, M.*; Wanner, H.*; Yui, Mikazu

JNC TN8400 99-011, 340 Pages, 1999/01

JNC-TN8400-99-011.pdf:26.06MB

This report provides thermodynamic data for predicting concentrations of palladium Pd, lead Pb, tin Sn, antimony Sb, niobium Nb and bismuth Bi in geologic environments, and contributes to an integration of the JNC chemical thermodynamic database, JNC-TDB (previously PNC-TDB), for the performance analysis of geological isolation system of high-level radioactive wastes. Besides treating hydrolysis in detail, this report focuses on the formation of complexes or compounds with chloride, fluoride, carbonate, nitrate, sulfate and phosphate. Other important inorganic ligands (sulfide for lead and antimony, ammonia for palladium) are also included. In this study, the specific ion interaction theory (SIT) approach is used to extrapolate thermodynamic constants to zero ionic strength at 25 $^{circ}$ C.