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Journal Articles

Extraction and separation between light and heavy lanthanides by -tetraoctyl-diglycolamide from organic acid

Sasaki, Yuji; Matsumiya, Masahiko*; Nakase, Masahiko*; Takeshita, Kenji*

Chemistry Letters, 49(10), p.1216 - 1219, 2020/10

https://doi.org/10.1246/cl.200431

Times Cited Count：9 Percentile：44.36(Chemistry, Multidisciplinary)

Lanthanide (Ln) extractions from organic acids to -dodecane by -tetraoctyl-diglycolamide (TODGA) were conducted. Four organic acids (lactic acid, malonic acid, tartaric acid, and citric acid) were employed. Although these acids stabilize lanthanides in the aqueous phase, a distribution ratio () greater 1 was obtained for heavy Ln. Ln patterns ((Ln) against atomic number of Ln) show maximum values of Ho and Er. In order to obtain high values, the addition of HNO $_{3}$ in aqueous phase is found to be effective.

Journal Articles

-radiation and H $_{2}$ O $_{2}$ induced oxidative dissolution of uranium(IV) oxide in aqueous solution containing phthalic acid

Kumagai, Yuta; Jonsson, M.*

Dalton Transactions (Internet), 49(6), p.1907 - 1914, 2020/02

https://doi.org/10.1039/c9dt03952j

Times Cited Count：0 Percentile：0.01(Chemistry, Inorganic & Nuclear)

This study aims to reveal possible involvements of organic acids in the oxidative dissolution of UO $_{2}$ . Using phthalic acid as a model compound, we have measured adsorption on UO $_{2}$ and investigated effects on the reaction between H $_{2}$ O $_{2}$ and UO $_{2}$ and on oxidative dissolution induced by -irradiation. Significant adsorption of phthalic acid was observed even at neutral pH. However, the reaction between H $_{2}$ O $_{2}$ and UO $_{2}$ in phthalic acid solution induced oxidative dissolution of U(VI) similarly to aqueous bicarbonate solution. These results indicate that even though phthalic acid adsorbs on the UO $_{2}$ surface, it is not involved in the interfacial reaction by H $_{2}$ O $_{2}$ . In contrast, the dissolution of U by irradiation was inhibited in aqueous phthalic acid solution, whereas H $_{2}$ O $_{2}$ generated by radiolysis was consumed by UO $_{2}$ . The inhibition suggests that radical species derived from phthalic acid was involved in the redox reaction process of UO $_{2}$ .

JAEA Reports

Organic acid dissolving in groundwater in the Mobara gas field

JNC TN8400 2000-030, 17 Pages, 2000/12

JNC-TN8400-2000-030.pdf:0.44MB

As a representative of natural marine groundwater, the author selected pumped water from a Quaternary sedimentary aquifer of the Mobara gas-field in Japan and measured the concentration of total organic carbon (TOC) and of organic acid anions (formic, acetic, lactic, succinic, humic, fulvic, propionic, valeric and butyric acids). The concentration of TOC ranged from 221 to 240mg/L. As organic acid anions, only succinic and fulvic acids were detected and each concentration was given to be from 5.8 0.5 to 8.30.3 and from 3.30.2 to 3.50.2mg/L, respectively. By consideration of the temperature and the [SO $_{4}$ $^{2-}$ ] of the groundwater, it is inferred that the organic acid has been significantly decomposed by activities of microbes, such as the fermentation process, CH $_{3}$ COO $^{-}$ + H $_{2}$ O = HCO $_{3}$ $^{-}$ + CH $_{4}$ .

JAEA Reports

An Estimation of influence of humic acid and organic matter originated from bentonite on samarium solubility

*; Sato, Haruo; *

JNC TN8400 99-059, 59 Pages, 1999/10

JNC-TN8400-99-059.pdf:1.54MB

Organic acids in groundwater are considered to form complexes and increase the solubility of radionuclides released from vitrified waste in a high-level radioactive waste (HLW) repository. To ivestigate whether the solubility of samarium (Sm) is influenced by organic substances, we measured Sm solubility in the presence of different organic substances and compared those values with results from thermodynamic predictions. Humic acid (Aldrich) is commercially available and soluble organic matter originated from bentonite were used as organic substances in this study. Consequently, the solubility of Sm showed a tendency to apparently increase with icreasing the concentration of humic acid, but in the presence of carbonate, thermodynamic predictions suggested that the dominant species are carbonate complexes and that the effect of organic substances are less than that of carbonate. Based on total organic carbon (TOC), the increase of Sm solubility measured with humic acid (Aldrich) was more significant than that in the case with soluble organic matter originated from bentonite. Since bentonite is presumed to include also simple organic matters of which stability constant for forming complexes is low, the effect of soluble organic matter originated from bentonite on the solubility of Sm is eonsidered to be less effective than that of humic acid (Aldrieh). Experimental values were compared with model prediction, propsed by Kim, based on data measured in a low pH region. Tentatively we calculated the increase in Sm solubility assuming complexation with humic acid. Trial calculations were carried out on the premise that the complexation reaction of metal ion with humic acid is based on neutralization process by 1-1 complexation. In this process, it was assumed that one metal ion coordinates with one unit of complexation sites which number of proton exchange sites is equal to ionic charge. Consequently, Kim's model indicated that carbonate complexes should be dominant ...

JAEA Reports