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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
Supramolecular organization of extractant molecules impacts metal ions separation behavior. Probing bulk and interfacial structures of the relevant systems is expected to provide key insights into the metal ion selectivity and kinetic aspects. The supramolecular features of two solvent extraction systems based on malonamide extractants, N,N,N′,N′-tetrahexylmalonamide (THMA) in toluene and N,N′-dimethyl-N,N′-dibutyl-2-tetradecylmalonamide (DBMA) in n-heptane, were studied using small-angle X-ray scattering for the organic bulk phases, as well as interfacial tension and neutron reflectivity measurements for the interfaces. In the bulk solution, THMA forms dimeric/trimeric associates but no aggregates in toluene, while DBMA forms large aggregates in n-heptane. On the other hand, THMA accumulates in a diffuse layer at the interface at high THMA concentration, whereas DBMA forms a compact but thinner layer. After Pd(II) extraction, the thickness of interfacial layers decreases in the case of THMA, and totally vanishes in the case of DBMA. Based on these new structural information, two mechanisms are proposed for Pd(II) and Nd(III) extraction with malonamides. In toluene, THMA associates slightly accumulate in the vicinity of the interface, then coordinate Pd(II) and diffuse into the organic bulk phase. In n-heptane, DBMA aggregates adsorb at the interface then pick up Nd(III) cations in their polar cores and finally diffuse into the bulk.
熊田 高之; 元川 竜平; 大場 洋次郎; 中川 洋; 関根 由莉奈; Micheau, C.; 上田 祐生; 杉田 剛; 美留町 厚; 佐々木 未来; et al.
Journal of Applied Crystallography, 56(6), p.1776 - 1783, 2023/12
被引用回数：1 パーセンタイル：65.66(Chemistry, Multidisciplinary)既存のメイン検出器および高位置分解能フォトマル検出器に加えて新規に導入した前面検出器を組み合わせることにより、波数0.002nm
から6nmにわたる散乱を3つの光学機器配置により切れ目なく測定できるようになった。またグラフィカルユーザーインターフェースの導入と併せて装置のユーザビリティが大幅に向上した。
Micheau, C.; 上田 祐生; 元川 竜平; Bauduin, P.*; Girard, L.*; Diat, O.*
Langmuir, 39(31), p.10965 - 10977, 2023/07
被引用回数：0 パーセンタイル：0(Chemistry, Multidisciplinary)Understanding clay flotation mechanisms has become a major concern because of the increasing level of environmental contamination of soil and ground water by heavy metals and radionuclides. Clays are often used as sorbents for extracting metals in indirect flotation processes but can function simultaneously as defoamers. However, how foam generation and stability depend on the molecular interactions between the clays and surfactant is still controversial. In the present study, an amine polyethoxylated surfactant was used as a bifunctional surfactant that collected clay particles and acted as a foaming agent in the flotation process. The pH conditions strongly affected the surfactant physicochemical properties, allowing the clay extraction efficiency to be tuned. The interfacial recovery factor of the clays almost reached 100 percent under acidic (pH lower than 6) and neutral (pH 6-10) conditions, whereas it was negative under alkaline conditions (pH higher than 10), contrary to expectations. To elucidate the mechanisms involved in the particle flotation process for each of the pH conditions, the bulk and foam phases were analyzed. The effects of electrostatic interactions between the solutes and multiscale structure on the clay extraction behavior were investigated by electrophoretic measurements, dynamic light scattering, small-angle neutron scattering, and image analysis. Based on these results, three flotation processes were found depending on pH range: surfactant foam fractionation at pH higher than 10; clay particle foam flotation at pH 6-10; and particle froth flotation at pH lower than 6.
Micheau, C.; 上田 祐生; 阿久津 和宏*; Bourgeois, D.*; 元川 竜平
Solvent Extraction and Ion Exchange, 41(2), p.221 - 240, 2023/02
被引用回数：1 パーセンタイル：51.1(Chemistry, Multidisciplinary)Malonamide derivatives, which are among the most extensively investigated extractants in solvent extraction of lanthanoids, actinides, and platinum group metal ions, were deuterated by using Pd/C and Rh/C catalysts with a D
O/2-propanol mixture. This method enables to replace the hydrogen atoms by deuterium atoms in the malonamide chemical structure with a controllable deuteration rate. The maximum rate reaches 75 percent approximately, determined by nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry. In addition, it has been demonstrated that extraction behavior of the malonamide molecules remains unchanged after the deuteration procedure. Deuterated malonamides should be a powerful tool for fundamental researches on solvent extraction systems, in particular, for structural analysis of the organic phases. The large difference in the neutron scattering cross-section between hydrogen and deuterium leads to a large difference in neutron scattering length density of the malonamide derivatives before and after the deuteration reaction. Therefore, using deuterated malonamides in small-angle neutron scattering and neutron reflectivity studies could give access to the nanoscopic structure of the specific solute species in the bulk organic phase and at the liquid-liquid interface, respectively. This deuteration method could become a general one and be extended to a wide variety of extractant molecules. In this way this work contributes to the development of the fundamental researches in solvent extraction systems.
solution; Comparison with a conventional organic phosphate上田 祐生; Micheau, C.; 徳永 紘平; 杉田 剛; 阿久津 和宏*; 元川 竜平
no journal, ,
The extraction of Zr(IV) from aqueous HNO solutions have been investigated extensively because the presence of Zr in the tri-n-butyl phosphate (TBP)-based PUREX process for reprocessing spent nuclear fuel is problematic. We have recently shown that a Zr-loaded organic phase from solvent extraction with TBP shows hierarchical aggregation behaviors of Zr(NO)
(TBP) complexes, which self-assemble into primary clusters that coalesce further to form superclusters. This supercluster formation portends the formation of the third phase. Fluorous solvents have excellent chemical properties and immiscibility with both water and organic solutions. Considering these properties, the hierarchical aggregating behaviors of Zr(IV) and the highly hydrophobic fluorous extractant should be different from that of Zr(IV) with TBP. We investigated the extraction performance of a fluoroalkylated phosphate of Zr(IV) from HNO solutions into perfluorohexane and compared them with the TBP in n-hexane.
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.; 上田 祐生; 元川 竜平; 阿久津 和宏*
no journal, ,
Malonamide derivatives, were deuterated by using Pd/C and Rh/C catalysts in a DO/-propanol mixture. The maximum rate reached about 75 percents, determined by NMR and electrospray ionization mass spectrometry. The extraction behavior of the malonamides was unchanged by deuteration. Deuterated malonamides are a powerful tool for fundamental research on solvent extraction systems and for structural analysis of organic phases. The large difference in the neutron scattering cross section between protium and deuterium leads to a similarly large difference in neutron scattering length density of malonamide derivatives before and after deuteration. Therefore, using deuterated malonamides in small-angle neutron scattering and neutron reflectivity studies may help to reveal the nanoscopic structure of the specific solute species in the bulk organic phase and at the liquid liquid interface, respectively.
元川 竜平; 熊田 高之; 中川 洋; 上田 祐生; 関根 由莉奈; Micheau, C.; 杉田 剛; 大場 洋次郎*
no journal, ,
研究用原子炉JRR-3に設置される中性子小角散乱装置(SANS-J)の最近の高度化・更新、及び、測定例を紹介する。SANS-Jで重視しているのは装置駆動とデータ取得に関する安定性とユーザビリティの向上である。以前に故障が頻発していた駆動軸の一部廃止や簡素化を行うとともに、エンコーダー付きモーターやGUIを導入して異常個所の早期発見・復旧を可能にし、ユーザビリティを向上させている。最近では、マシンタイム競争率の高い同装置のスループットの拡大および性能向上を主眼にした改良を進めている。フライトチューブの手前に
He二次元検出器を導入して、以前から要望が高かった1nm 
Q 7nmの波数領域を効率良く測定できるようにした。また、既存の中性子集光レンズを用いることで、試料-検出器間距離10m位置での入射中性子ビーム強度を3倍に引き上げることに成功した。今後は、超小角散乱測定用フォトマル検出器をフラットパネル検出器に置き換える等の変更を計画している。
上田 祐生; Micheau, C.; 元川 竜平; 徳永 紘平; 阿久津 和宏*; 山田 悟史*
no journal, ,
発表者が開発した新規フルオラス抽出系は、優れた抽出分離能力と第三相の抑制能力を有するが、その起源は明らかになっていない。本発表では、フルオラス抽出系と従来の抽出系である有機抽出系における金属イオン抽出能力の違いの起源を明らかにするため、X線吸収微細構造(EXAFS)、中性子反射率法(NR)、及び中性子小角散乱法(SANS)を用いて金属イオン近傍、界面、及び抽出相における構造化学的観点から検証した。EXAFSの結果から、金属イオンの配位構造はフルオラス抽出系と有機抽出系で大きな違いは観られなかったのに対し、NRとSANSの結果から、界面及びバルク抽出相における抽出剤分子の集積構造に及ぼす硝酸分子の影響に違いが観られた。この違いが、フルオラス抽出系の高い抽出能力と第三相生成の抑制に寄与していると推察している。今後は、本研究で得られた知見を基に、フルオラス抽出系の改良を取り組むことを計画している。
