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論文

Quantitative analysis of Cs extraction by some dialkoxycalix[4]arene-crown-6 extractants

Simonnet, M.; 宮崎 有史*; 鈴木 伸一; 矢板 毅

Solvent Extraction and Ion Exchange, 37(1), p.81 - 95, 2019/00

 被引用回数:4 パーセンタイル:18.42(Chemistry, Multidisciplinary)

Cesium extraction from acidic media by seven dialkoxy-calix[4]arene-crown-6 compounds in several diluents was studied. 2-Nonanone was found to be a suitable diluent for cesium extraction. Nitric acid concentration variation reveals a maximum distribution ratio, whose position depends on extractant and diluent. This maximum was explained quantitatively by a competitive extraction of H$$^{+}$$. An analytical mass-action extraction model accounting for activity effects is proposed that fits correctly the different datasets. The analysis showed a nitrate hyper-stoichiometry in alkyl ketone diluents. This effect yields efficient back-extraction at low acidity. Benzo substitution on the crown ether lowers nitric acid extraction, improves sodium separation, but also degrades potassium and rubidium separation.

口頭

1,10-phenanthroline carboxamide ligands for lanthanide separation; Diluent effect

Simonnet, M.; 小林 徹; 鈴木 伸一; 矢板 毅

no journal, , 

Efficient separation of rare-earth elements has recently been under a renewed interest. One of the most common elemental separation method is liquid-liquid extraction, for which the state of the art is wide due to the similarities with the studies on actinides separation from lanthanides. Therefore, many different extractants can be found in literature, among which 1,10-phenanthroline-based ligands have shown a strong ability for the extraction of trivalent elements. In this study, we focused on 1,10-phenanthroline carboxamide compounds, because they can selectively extract one lanthanide from the series, with the nature of this lanthanide dependent on the extractant structure. Some compounds were tested in different media, and it was found that the nature of the diluent and the composition of the aqueous feed also yield to a maximum shift among the lanthanide series. This study thus aims at emphasizing diluent effect on lanthanide extraction by 1,10-phenanthroline carboxamide ligands.

口頭

Cesium extraction by calixarenes crown-ether; Diluent effect

Simonnet, M.; 宮崎 有史*; 鈴木 伸一; 矢板 毅

no journal, , 

$$^{137}$$Cs is a troublesome fission product for both nuclear waste reprocessing and the cleaning of contaminated areas (Fukushima). Because Cs belongs to the alkali elements, it is hard to separate from Na and K, whose natural abundances are high. Calixarenes crown-ether were found to be efficient alkali extractants, with the alkali selectivity determined by the number of ether functions. It was found that ligands with 6 ether functions are optimum for cesium whilst 4 is optimum for Na, yielding great Na separation factors. However, the resulting high oxygen contents yields a low solubility in aliphatic diluents. Different diluents were thus used in literature, such as alcohols, ketones, chloroform, nitrophenylalkylether or dodecane with a modifier. Whilst the distribution ratios greatly varied along with the diluent, few studies focused on understanding this phenomenon. The aim of the present work is thus to study the diluent effect at both macroscopic (distribution ratio and separation factor comparison) and microscopic (EXAFS analysis) scales. For the latter study, two diluents, chloroform and 2-nonanone, were chosen. Their properties (density, viscosity, dielectric constant, water solubility) are all different, except from the calixarene crown-ether solubility which is high in both cases. Additional interactions between the diluent and the counterion were also investigated. The study focuses on acidic aqueous solutions only.

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