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Micheau, C.; 上田 祐生; 元川 竜平; 阿久津 和宏*; 山田 悟史*; 山田 雅子*; Moussaoui, S. A.*; Makombe, E.*; Meyer, D.*; Berthon, L.*; et al.
Journal of Molecular Liquids, 401, p.124372_1 - 124372_12, 2024/05
被引用回数：1 パーセンタイル：65.37(Chemistry, Physical)Supramolecular organization of amphiphilic extractant molecules is involved in metal cation selectivity and separation kinetics during solvent extraction. The relationship between extractant associates/aggregates formed in the organic bulk phase and at the liquid-liquid interface is poorly understood even though it affects the extraction mechanism. The nanoscopic structures of the extraction systems N,N,N',N'-tetrahexylmalonamide (THMA) in toluene and N,N'-dibutyl-N,N'-dimethyl-2-tetradecylmalonamide (DBMA) in n-heptane, used for either Pd(II) or Nd(III) selective extraction from an acidic aqueous phase, were examined. These systems present markedly different affinity for Pd(II) and Nd(III), and extraction kinetics. Extractant organization in the organic bulk phase and at the interface were compared by small-angle X-ray scattering, interfacial tension, and neutron reflectivity. THMA in toluene forms small associates in the organic bulk phase and accumulates in a diffuse layer at the interface, decreasing Pd(II) coordination probability and resulting in slow extraction. DBMA in n-heptane forms large aggregates and a compact, dense interfacial layer, resulting in rapid Pd(II) and Nd(III) extraction. Thus, Pd(II) extraction is driven by interfacial coordination alone, whereas the incorporation of Nd(III) into the core of large aggregates governs Nd(III) extraction in the interfacial layer. These results suggest that the interface should be described as a nanoscale interphase containing a high extractant concentration compared with the organic bulk phase.
Tamain, C.*; Bonato, L.*; Aupiais, J.*; Dumas, T.*; Guillaumont, D.*; Barkleit, A.*; Berthon, C.*; Solari, P. L.*; 池田 篤史; Guilbard, P.*; et al.
European Journal of Inorganic Chemistry, 2020(14), p.1331 - 1344, 2020/04
被引用回数：4 パーセンタイル：26.35(Chemistry, Inorganic & Nuclear)水溶液中における三価アメリシウム(Am(III))とクエン酸(Citric acid)の配位・錯形成反応について、可視吸収分光, NMR, X戦吸収分光(EXAFS), TRLFS、及び電気泳動測定を実施し、溶液中に生成している化学種の数、種類、及びその配位・錯形成状態についての検討を行った。当該実験結果はさらに量子化学計算の結果とも組み合わせ、生成化学種の詳細な配位・錯体構造について検討した。
Micheau, C.; 上田 祐生; 元川 竜平; Moussaoui, S.*; Makombe, E.*; Daniel, M.*; Berthon, L.*; Bourgeois, D.*; 阿久津 和宏*
no journal, ,
The DIAMEX process aims to separate minor f-elements using malonamide as extractant molecules such as N,N'-dimethyl-N,N'-dibutyl-tetradecyl-malonamide (DBMA). Recently, Poirot studied the effect of n-heptane and toluene on the selectivity of DBMA between Pd and Nd and have conclude that Pd extraction is driven by coordination whereas Nd extraction is driven by extractant aggregation. More recently, a specific study on tetrahexylmalonamide (THMA) in toluene demonstrated a superior selectivity for Pd compared to DBMA. THMA molecular structure suggests poor aptitude for aggregation compared with DBMA, and has been much less characterized. Supramolecular features of two different solvent extraction systems based on malonamide extractants, THMA in toluene and DBMA in heptane, have been studied using characterization techniques dedicated to bulk organic phase organisation, ie. small angle X-ray scattering, and to interface characterization, ie. neutron reflectivity and interfacial tension.
Micheau, C.; 元川 竜平; 上田 祐生; 阿久津 和宏*; 山田 悟史*; 山田 雅子*; Bourgeois, D.*; Berthon, L.*
no journal, ,
DIAMEX process uses malonamide molecules for the separation and co-extraction of actinides and lanthanides from the raffinate of the PUREX process. Recent study on the use of malonamide molecules for the extraction and separation of PdII and NdIII by solvent extraction has pointed out two main driving forces that could explain the selectivity. Coordination and extractant aggregation. It has been demonstrated that Pd only needs coordination to be extracted whereas Nd needs in addition the aggregation of the extractant. Extractant aggregation can be beneficial for solvent extraction process if it can be controlled to enhance separation. In order to confirm a potential correlation between the separation efficiency and the extractant aggregation, a model malonamide molecule was investigated. This extractant was dissolved, at room temperature, in pure n-heptane, pure toluene, and mixtures of both solvents at different ratios, and contacted with different nitric acid solutions with and without metal ions. These two solvents possess different relative permittivity, and topology with an aromatic ring for toluene that could lead to additional pi-interaction with the extractant. Distribution ratios of Pd and Nd, as well as separation factors were determined. In parallel, small angle neutron scattering technique was used to determine the size and shape of the aggregates formed. From these results, it can be said that heptane promotes the formation of large assemblies, whereas the presence of toluene tends to reduce the size of the assemblies which was directly correlated to extraction separation efficiency.
