Refine your search:     
Report No.
Search Results: Records 1-20 displayed on this page of 107

Presentation/Publication Type

Initialising ...


Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...


Initialising ...


Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Recent progress in ionic liquid extraction for the separation of rare earth elements

Okamura, Hiroyuki; Hirayama, Naoki*

Analytical Sciences, 37(1), p.119 - 130, 2021/01

 Times Cited Count:1 Percentile:16.03(Chemistry, Analytical)

This review summarizes recent progress in solvent extraction of rare earth elements (REEs) using an ionic liquid (IL) as the extraction solvent. These IL extraction systems are advantageous owing to the affinity of ILs for both charged and neutral hydrophobic species, in contrast to conventional organic solvent extraction systems. Herein, REE extraction studies using ILs are detailed and classified based on the type of extraction system. In IL extraction systems, the extracted complexes are often different from those in organic solvent systems, and the REE extraction and separation efficiencies are often significantly enhanced. Synergistic IL extraction is an effective approach to improving the extractability and separability of REEs. The development of novel task-specific ionic liquids (TSILs) suitable for IL extraction systems is also effective for REE separation.

Journal Articles

Synergistic enhancement of the extraction and separation efficiencies of lanthanoid(III) ions by the formation of charged adducts in an ionic liquid

Okamura, Hiroyuki; Mizuno, Masayoshi*; Hirayama, Naoki*; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*

Industrial & Engineering Chemistry Research, 59(1), p.329 - 340, 2020/01

 Times Cited Count:3 Percentile:41.33(Engineering, Chemical)

The synergistic ionic-liquid extraction and extraction equilibrium of lanthanoid(III) (Ln(III)) ions have been investigated using 2-thenoyltrifluoroacetone (Htta) and trioctylphosphine oxide (TOPO) in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C$$_{4}$$mim][Tf$$_{2}$$N]). The selective synergistic effect for heavier Ln(III) ions was found using a combination of Htta and TOPO in [C$$_{4}$$mim][Tf$$_{2}$$N], leading to enhanced separability among Ln(III) ions. The extracted Ln(III) species and the extraction constants in the Htta-TOPO system were determined by three-dimensional extraction equilibrium analysis. The selective synergism for heavier Ln(III) ions in the Htta-TOPO system was ascribed to the formation of hydrophobic, charged adducts, such as Ln(tta)$$_{2}$$(TOPO)$$_{3}$$$$^{+}$$ and Ln(tta)(TOPO)$$_{3}$$$$^{2+}$$, in [C$$_{4}$$mim][Tf$$_{2}$$N].

Journal Articles

Experimental study of Gamow-Teller transitions via the high-energy-resolution $$^{18}$$O($$^3$$He,$$t$$)$$^{18}$$F reaction; Identification of the low-energy "super" -Gamow-Teller state

Fujita, Hirohiko*; Fujita, Yoshitaka*; Utsuno, Yutaka; Yoshida, Kenichi*; Adachi, Tatsuya*; Algora, A.*; Csatl$'o$s, M.*; Deaven, J. M.*; Estevez-Aguado, E.*; Guess, C. J.*; et al.

Physical Review C, 100(3), p.034618_1 - 034618_13, 2019/09

 Times Cited Count:2 Percentile:52.25(Physics, Nuclear)

no abstracts in English

Journal Articles

Extraction ability of 4-benzoyl-3-phenyl-5-isoxazolone towards 4f-ions into ionic and molecular media

Atanassova, M.*; Okamura, Hiroyuki; Eguchi, Ayano; Ueda, Yuki; Sugita, Tsuyoshi; Shimojo, Kojiro

Analytical Sciences, 34(8), p.973 - 978, 2018/08

 Times Cited Count:11 Percentile:29.49(Chemistry, Analytical)

The distribution constants of 4-benzoyl-3-phenyl-5-isoxazolone (HPBI) and deprotonated one (PBI$$^{-}$$) between hydrophobic ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C$$_{1}$$C$$_{4}$$im][Tf$$_{2}$$N]) and aqueous phases were determined, together with the acid-dissociation constant of HPBI. The solvent extraction of three selected lanthanoid ions (La$$^{3+}$$, Eu$$^{3+}$$, and Lu$$^{3+}$$) with HPBI from aqueous nitrate phase into [C$$_{1}$$C$$_{4}$$im][Tf$$_{2}$$N] has been investigated. Application of the ionic liquid as the extracting phase greatly enhanced the extraction performance of HPBI for lanthanoid ions compared with that in the chloroform system. The composition of the extracted species was established to be anionic tetrakis entities, Ln(PBI)$$_{4}$$$$^{-}$$, for light, middle, and heavy lanthanoid ions in an ionic environment.

Journal Articles

A New technique for solvent extraction; Emulsion flow method

Okamura, Hiroyuki

Kagaku To Kyoiku, 66(6), p.286 - 287, 2018/06

The emulsion flow method has recently been developed and is an extraction technique based on the liquid-liquid system. This method has attracted much attention as an innovative technique combining simplicity and high performance. The emulsion flow apparatus can actualize solvent extraction by only solution sending. In this article, mechanism of the emulsion flow method was explained and recovery and removal of uranium was introduced as an application example.

Journal Articles

Synergistic extraction equilibrium of lanthanide(III) Ions with benzoylacetone and a neutral ligand in an ionic liquid

Hatakeyama, Mizuki*; Nishiyama, Yoshio*; Nagatani, Hirohisa*; Okamura, Hiroyuki; Imura, Hisanori*

Solvent Extraction Research and Development, Japan, 25(2), p.79 - 89, 2018/00

 Times Cited Count:7 Percentile:50.6(Chemistry, Multidisciplinary)

The synergistic extraction of trivalent lanthanide ions (Ln(III)) with benzoylacetone (Hba) and trioctyphosphine oxide (TOPO) in an ionic liquid (IL), 1-butyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide ([Bmim][Tf$$_{2}$$N]), has been investigated. The extractability of Ln(III) with Hba was significantly enhanced in the presence of TOPO. The composition and extraction constants of the extracted species for each Ln(III) were determined by 3-dimensional equilibrium analysis. It was found that all Ln(III) were extracted as cationic ternary complexes such as Ln(ba)$$_{2}$$(TOPO)$$_{2}$$$$^{+}$$ or Ln(ba)(TOPO)$$_{4}$$$$^{2+}$$ with Hba and TOPO. Furthermore, the formation constants of the cationic ternary complexes in the IL indicate that Lu(ba)(TOPO)$$_{4}$$$$^{2+}$$ is the most stable complex in the IL.

Journal Articles

Ionic liquid extraction of metal(II, III) complexes with macrocyclic and chelating ligands

Okamura, Hiroyuki

Bunseki Kagaku, 66(7), p.531 - 532, 2017/07

This paper summarizes the author's doctoral thesis on analytical chemistry. In this study, the ionic liquid (IL) extraction of various metal(II, III) complexes with macrocyclic and anionic chelating ligands has been investigated to clarify the solvent effect of ILs and to demonstrate the specificity and superiority of the IL extraction systems over conventional ones. The evaluation of the extraction equilibrium of Eu(III) with 2-thenoyltrifluoroacetone (Htta) in 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C$$_{n}$$mim][Tf$$_{2}$$N]) and time-resolved laser-induced fluorescence spectroscopy revealed the specific solute-solvent interactions between Eu(tta)$$_{3}$$ and [C$$_{n}$$mim][Tf$$_{2}$$N]. The IL synergistic extraction with Htta and ${it cis}$-dicyclohexano-18-crown-6 was developed. The extractability of lighter lanthanides(III) was remarkably enhanced by a synergistic effect of crown ethers. A macrocyclic ligand (H$$_{2}$$$$beta$$DA18C6) composed of diaza-18-crown-6 and two 4-acyl-5-pyrazolones was synthesized for the extraction of Sr(II). The extraction performance of H$$_{2}$$$$beta$$DA18C6 was significantly enhanced only in [C$$_{n}$$mim][Tf$$_{2}$$N] by the intramolecular cooperative effect.

Journal Articles

A Comprehensive extraction study using a mono-alkylated diglycolamic acid extractant; Comparison between a secondary amide group and a tertiary amide group

Sugita, Tsuyoshi; Fujiwara, Iori*; Okamura, Hiroyuki; Oshima, Tatsuya*; Baba, Yoshinari*; Naganawa, Hirochika; Shimojo, Kojiro

Solvent Extraction Research and Development, Japan, 24(2), p.61 - 69, 2017/05

We investigated an influence of amide group in diglycolamic acid-type extractants on extraction property of metal ions. The extraction characteristics of $$N$$-dodecyldiglycolamic acid (C$$_{12}$$DGAA), with a secondary amide group, for 56 metal ions have been investigated, and compared with those of $$N,N$$-dioctyldiglycolamic acid (DODGAA) with a tertiary amide group. Compared with DODGAA, C$$_{12}$$DGAA has a poor extraction performance and separation ability for rare-earth metal ions, except for Sc(III). However, C$$_{12}$$DGAA tended to provide better extraction for relatively small-sized metal ions than DODGAA. In addition, it was found that C$$_{12}$$DGAA enables the selective removal of Hg(II) from aqueous solutions containing various divalent metal ions.

Journal Articles

Role of Tf$$_{2}$$N$$^{-}$$ anions in the ionic liquid-water distribution of europium(III) chelates

Okamura, Hiroyuki; Aoyagi, Noboru; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*

RSC Advances (Internet), 7(13), p.7610 - 7618, 2017/01

 Times Cited Count:12 Percentile:41.94(Chemistry, Multidisciplinary)

The role of bis(trifluoromethanesulfonyl)imide (Tf$$_{2}$$N$$^{-}$$) anions in the ionic liquid-water distribution systems of the Eu(III) chelates with 2-thenoyltrifluoroacetone (Htta) was investigated by the liquid-liquid distribution and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The effect of the ionic liquids on the distribution constant of Eu(tta)$$_{3}$$ was evaluated by the regular solution theory. The distribution constant of Eu(tta)$$_{3}$$ in 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C$$_{n}$$mim][Tf$$_{2}$$N]) was increased dramatically by the solvation effects of Eu(tta)$$_{3}$$ in [C$$_{n}$$mim][Tf$$_{2}$$N]. TRLFS for [Eu(tta)$$_{3}$$(H$$_{2}$$O)$$_{3}$$] synthesized revealed that the Eu(tta)$$_{3}$$ chelate was almost completely dehydrated in a series of [C$$_{n}$$mim][Tf$$_{2}$$N]. The Eu(tta)$$_{3}$$ chelate exists as di- or tri-hydrates in 1-ethyl-3-methylimidazolium perchlorate ([C$$_{2}$$mim][ClO$$_{4}$$]) containing 20 M water, whereas mono-hydrated chelate was formed in [C$$_{2}$$mim][Tf$$_{2}$$N, ClO$$_{4}$$] in the presence of 0.50 M Tf$$_{2}$$N$$^{-}$$ and 20 M water. These results show that the coordinated water molecules of [Eu(tta)$$_{3}$$(H$$_{2}$$O)$$_{3}$$] were replaced by the Tf$$_{2}$$N$$^{-}$$ anions. In fact, an anionic adduct, [Eu(tta)$$_{3}$$(Tf$$_{2}$$N)]$$^{-}$$, was observed by electrospray ionization mass spectrometry in the presence of [C$$_{4}$$mim][Tf$$_{2}$$N].

Journal Articles

Solvent extraction and synergistic effect using an ionic liquid

Okamura, Hiroyuki; Shimojo, Kojiro

Ion Ekitai Kenkyu Saizensen To Shakai Jisso, p.220 - 227, 2016/12

Solvent extraction is a separation method based on the difference in the distribution of solutes between two immiscible liquid phases. Recently, ionic liquids have been widely investigated as novel extraction media. Solvent properties of an ionic liquid can be adjusted by combination of a cationic and an anionic component. It is, therefore, possible to provide an attractive reaction field as an extraction medium. In this article, specific extraction phenomena observed in the ionic liquid extraction system for metal ions were introduced.

Journal Articles

Studies of high density baryon matter with high intensity heavy-ion beams at J-PARC

Sako, Hiroyuki; Harada, Hiroyuki; Sakaguchi, Takao*; Chujo, Tatsuya*; Esumi, Shinichi*; Gunji, Taku*; Hasegawa, Shoichi; Hwang, S.; Ichikawa, Yudai; Imai, Kenichi; et al.

Nuclear Physics A, 956, p.850 - 853, 2016/12

 Times Cited Count:10 Percentile:28.91(Physics, Nuclear)

Journal Articles

Extraction behavior of rare-earth elements using a mono-alkylated diglycolamic acid extractant

Shimojo, Kojiro; Fujiwara, Iori*; Fujisawa, Kiyoshi*; Okamura, Hiroyuki; Sugita, Tsuyoshi; Oshima, Tatsuya*; Baba, Yoshinari*; Naganawa, Hirochika

Solvent Extraction Research and Development, Japan, 23(2), p.151 - 159, 2016/05

Liquid-liquid extraction of rare-earth (RE) cations has been investigated using $$N$$-dodecyldiglycolamic acid (C$$_{12}$$DGAA) with a secondary amide group, and compared with that using $$N,N$$-dioctyldiglycolamic acid (DODGAA) with a tertiary amide group. C$$_{12}$$DGAA enables quantitative transfer of all RE cations from moderately acidic solution, while being selective toward the heavier RE cations, and performs better than typical carboxylic-acid-type extractants. However, C$$_{12}$$DGAA provides low extraction performance and separation ability for RE cations compared with DODGAA because of the weaker basicity of the amide oxygen. Slope analysis demonstrated that RE$$^{3+}$$ transfer with C$$_{12}$$DGAA proceeded through a proton-exchange reaction, forming a 1:3 complex, RE(C$$_{12}$$DGAA)$$_{3}$$. Structural characterization by X-ray diffraction revealed that three $$N$$-butyldiglycolamic acid (C$$_{4}$$DGAA) molecules coordinated to the La$$^{3+}$$ central ion in a tridentate fashion and the La$$^{3+}$$ primary coordination sphere consisted of three oxygen atoms from the amide group, three oxygen atoms from the ether group, and three oxygen atoms from the carboxy group.

Journal Articles

Seismic PRA for Japan Sodium-cooled Fast Reactor (JSFR)

Naruto, Kenichi*; Nishino, Hiroyuki; Kurisaka, Kenichi; Yamano, Hidemasa; Okano, Yasushi; Okamura, Shigeki*; Eto, Masao*

Proceedings of 9th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-9) (CD-ROM), 10 Pages, 2014/11

Journal Articles

Intramolecular cooperative effect of a macrocyclic receptor bearing $$beta$$-diketone fragments on the extraction of strontium into an ionic liquid

Okamura, Hiroyuki; Naganawa, Hirochika; Imura, Hisanori*; Shimojo, Kojiro

Proceedings of 20th International Solvent Extraction Conference (ISEC 2014), p.1046 - 1051, 2014/09

Journal Articles

Comprehensive extraction study using $$N$$,$$N$$-dioctyldiglycolamic acid

Shimojo, Kojiro; Nakai, Ayaka*; Okamura, Hiroyuki; Saito, Takumi*; Ohashi, Akira*; Naganawa, Hirochika

Analytical Sciences, 30(4), p.513 - 517, 2014/04

 Times Cited Count:9 Percentile:60.15(Chemistry, Analytical)

Journal Articles

Highly selective synergism for the extraction of lanthanoid(III) ions with $$beta$$-diketones and trioctylphosphine oxide in an ionic liquid

Okamura, Hiroyuki; Takagi, Hitomi*; Isomura, Taku*; Morita, Kotaro*; Nagatani, Hirohisa*; Imura, Hisanori*

Analytical Sciences, 30(3), p.323 - 325, 2014/03

 Times Cited Count:23 Percentile:26.69(Chemistry, Analytical)

Journal Articles

Highly efficient extraction separation of lanthanides using a diglycolamic acid extractant

Shimojo, Kojiro; Aoyagi, Noboru; Saito, Takumi*; Okamura, Hiroyuki; Kubota, Fukiko*; Goto, Masahiro*; Naganawa, Hirochika

Analytical Sciences, 30(2), p.263 - 269, 2014/02

 Times Cited Count:36 Percentile:13.92(Chemistry, Analytical)

Journal Articles

Extraction behavior and selective separation of lead(II) using $$N$$,$$N$$-dioctyldiglycol amic acid

Shimojo, Kojiro; Nakai, Ayaka; Okamura, Hiroyuki; Ohashi, Akira*; Naganawa, Hirochika

Analytical Sciences, 29(1), p.147 - 150, 2013/01

 Times Cited Count:11 Percentile:55.26(Chemistry, Analytical)

Journal Articles

Specific cooperative effect of a macrocyclic receptor for metal ion transfer into an ionic liquid

Okamura, Hiroyuki; Ikeda, Atsushi*; Saito, Takumi*; Aoyagi, Noboru; Naganawa, Hirochika; Hirayama, Naoki*; Umetani, Shigeo*; Imura, Hisanori*; Shimojo, Kojiro

Analytical Chemistry, 84(21), p.9332 - 9339, 2012/11

 Times Cited Count:23 Percentile:30.85(Chemistry, Analytical)

Journal Articles

Laser-induced fluorescence and infrared spectroscopic studies on the specific solvation of tris(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)europium(III) in an ionic liquid

Okamura, Hiroyuki; Sakae, Hiroki*; Kidani, Keiji*; Hirayama, Naoki*; Aoyagi, Noboru; Saito, Takumi*; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*

Polyhedron, 31(1), p.748 - 753, 2012/01

 Times Cited Count:22 Percentile:13.62(Chemistry, Inorganic & Nuclear)

107 (Records 1-20 displayed on this page)