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Journal Articles

New design of a sample cell for neutron reflectometry in liquid-liquid systems and its application for studying structures at air-liquid and liquid-liquid interfaces

Akutsu-Suyama, Kazuhiro*; Yamada, Norifumi*; Ueda, Yuki; Motokawa, Ryuhei; Narita, Hirokazu*

Applied Sciences (Internet), 12(3), p.1215_1 - 1215_10, 2022/02

no abstracts in English

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2019

Nakano, Masanao; Fujii, Tomoko; Nemoto, Masashi; Tobita, Keiji; Seya, Natsumi; Nishimura, Shusaku; Hosomi, Kenji; Nagaoka, Mika; Yokoyama, Hiroya; Matsubara, Natsumi; et al.

JAEA-Review 2020-069, 163 Pages, 2021/02

JAEA-Review-2020-069.pdf:4.78MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2019 to March 2020. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.

Journal Articles

Precious metal separations

Narita, Hirokazu*; Kasuya, Ryo*; Suzuki, Tomoya*; Motokawa, Ryuhei; Tanaka, Mikiya*

Encyclopedia of Inorganic and Bioinorganic Chemistry (Internet), 28 Pages, 2020/12

Journal Articles

Proton chelating ligands drive improved chemical separations for rhodium

Narita, Hirokazu*; Nicolson, R. M.*; Motokawa, Ryuhei; Ito, Fumiyuki*; Morisaku, Kazuko*; Goto, Midori*; Tanaka, Mikiya*; Heller, W. T.*; Shiwaku, Hideaki; Yaita, Tsuyoshi; et al.

Inorganic Chemistry, 58(13), p.8720 - 8734, 2019/07

 Times Cited Count:6 Percentile:55.42(Chemistry, Inorganic & Nuclear)

Journal Articles

Speciation of ruthenium(III) chloro complexes in hydrochloric acid solutions and their extraction characteristics with an amide-containing amine compound

Suzuki, Tomoya*; Ogata, Takeshi*; Tanaka, Mikiya*; Kobayashi, Toru; Shiwaku, Hideaki; Yaita, Tsuyoshi; Narita, Hirokazu*

Metals, 8(7), p.558_1 - 558_10, 2018/07

AA2018-0670.pdf:2.11MB

 Times Cited Count:9 Percentile:63.65(Materials Science, Multidisciplinary)

The refining of platinum group metals is based mainly on solvent extraction methods, whereas Ru is selectively recovered by distillation as RuO$$_4$$. Replacement of distillation byextraction is expected to simplify the purification process. To develop an effective extraction system for Ru, we analyzed the Ru species in HCl with UV-Vis and EXAFS spectroscopies, and we examined the properties of Ru extracted with N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide) amine (EHBAA). EXAFS and UV-Vis spectra of Ru in HCl solutions revealed that the predominant Ru species in 0.5-10 M HCl solutions changed from [RuCl$$_4$$(H$$_2$$O)$$_2$$]$$^-$$ to [RuCl$$_6$$]$$^3$$$$^-$$ with the HCl concentration. The extraction percentages of Ru in the EHBAA system increased with increasing HCl concentration, reached 80% at [HCl] = 5 M, and decreased athigher HCl concentrations. EXAFS analysis of the extracted complex indicated that the Ru$$^3$$$$^+$$ had 5 Cl$$^-$$ and 1 H$$_2$$O in its inner coordination sphere. The similarity of the dependence on HCl concentrations of the extraction in the EHBAA system and the distribution profile of [RuCl$$_5$$(H$$_2$$O)]$$^2$$$$^-$$ on [RuCl$$_n$$(H$$_2$$O)$$_6$$$$_-$$$$_n$$]$$^3$$$$^-$$$$^n$$ suggested that the EHBAA extracted the pentachlorido species.

Journal Articles

Comparison of the extractabilities of tetrachloro- and tetrabromopalladate(II) ions with a thiodiglycolamide compound

Narita, Hirokazu*; Maeda, Motoki*; Tokoro, Chiharu*; Suzuki, Tomoya*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi

Analytical Sciences, 33(11), p.1305 - 1309, 2017/11

 Times Cited Count:6 Percentile:33.73(Chemistry, Analytical)

Journal Articles

Recent research in solvent extraction of platinum group metals

Narita, Hirokazu*; Suzuki, Tomoya*; Motokawa, Ryuhei

Nihon Kinzoku Gakkai-Shi, 81(4), p.157 - 167, 2017/04

 Times Cited Count:9 Percentile:55.7(Metallurgy & Metallurgical Engineering)

Journal Articles

Selective extraction of Pt(IV) over Fe(III) from HCl with an amide-containing tertiary amine compound

Maeda, Motoki*; Narita, Hirokazu*; Tokoro, Chiharu*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi

Separation and Purification Technology, 177, p.176 - 181, 2017/04

 Times Cited Count:16 Percentile:56.83(Engineering, Chemical)

Journal Articles

Small-angle neutron scattering study of specific interaction and coordination structure formed by mono-acetyl-substituted dibenzo-20-crown-6-ether and cesium ions

Motokawa, Ryuhei; Kobayashi, Toru; Endo, Hitoshi*; Ikeda, Takashi; Yaita, Tsuyoshi; Suzuki, Shinichi; Narita, Hirokazu*; Akutsu, Kazuhiro*; Heller, W. T.*

Journal of Nuclear Science and Technology, 53(8), p.1205 - 1211, 2016/08

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Journal Articles

Extraction of Am(III) and Lanthanide(III) ions from HNO$$_{3}$$ solutions using ${it N,N'}$-dimethyl-${it N,N'}$-diphenylpyridine-2,6-dicarboxyamide

Shimada, Asako; Yaita, Tsuyoshi; Narita, Hirokazu; Tachimori, Shoichi; Kimura, Takaumi; Okuno, Kenji*; *

Solvent Extraction Research and Development, Japan, 11, p.1 - 10, 2004/04

The distribution ratio (${it D}$) of Am(III) and lighter Ln(III) in the extraction with ${it N,N'}$-dimethyl-${it N,N'}$-diphenylpyridine-2,6-dicarboxyamide(DMDPhPDA) from HNO$$_{3}$$ solutions were determined. The D's increased with an increase of HNO$$_{3}$$ concentration. Additionally, separation of Am(III) from Ln(III) were confirmed for all the HNO$$_{3}$$ concentration range (S.F.=(D$$_{Am}$$/D$$_{Ln}$$)). From 4 M HNO$$_{3}$$ solution with 0.5 M DMDPhPDA CHCl$$_{3}$$ solution, the ${it D}$'s of Am(III), Eu(III) and Nd(III) were 1.3, 0.25 and 0.24, respectively. This result suggests that Am(III) can be separated from Eu and Nd in the higher HNO$$_{3}$$ concentration region than that has been reported so far. These ${it D}$'s value and the S.F. were reproduced in the extraction from the metal concentration range from 10$$^{-1}$$ M order to 10$$^{-8}$$ M.

Journal Articles

Extraction studies of lanthanide(III) ions with ${it N,N'}$-dimethyl-${it N,N'}$-diphenylpyridine-2,6-dicarboxyamide(DMDPhPDA) from nitric acid solutions

Shimada, Asako; Yaita, Tsuyoshi; Narita, Hirokazu; Tachimori, Shoichi; Okuno, Kenji*

Solvent Extraction and Ion Exchange, 22(2), p.147 - 161, 2004/03

 Times Cited Count:60 Percentile:80.68(Chemistry, Multidisciplinary)

The distribution ratios of lanthanides with ${it N,N'}$-dimethyl-${it N,N'}$-diphenylpyridine-2,6-dicarboxyamide(DMDPhPDA) from 1-5M nitric acid solutions were determined and the extraction mechanism was discussed on the basis of the slope analyses of acid and ligand concentration dependencies and lanthanide patterns (variation of the distribution ratio as a function of ionic radius). The lanthanide extractions were explained through two mechanisms from the standpoint of the formation of the extracted complex as follows: (1) the formation of inner-sphere complex with two DMDPhPDA molecules for light lanthanides in the extraction from HNO$$_{3}$$ less than 3M, and (2) the formation of outer-sphere complex with the third DMDPhPDA molecules in addition to the inner-sphere complex in the extraction of light lanthanides from HNO$$_{3}$$ more than 3M, and those of heavy lanthanides from 1-5M HNO$$_{3}$$ solutions. Nitric acid concentration is more influential than the ligand concentration in the formation of outer-sphere complex.

Journal Articles

Local structure of molten LaCl$$_3$$ by K-absorption edge XAFS

Okamoto, Yoshihiro; Shiwaku, Hideaki; Yaita, Tsuyoshi; Narita, Hirokazu; Tanida, Hajime*

Journal of Molecular Structure, 641(1), p.71 - 76, 2002/10

 Times Cited Count:36 Percentile:69.09(Chemistry, Physical)

The local structure of molten LaCl$$_3$$ was investigated by X-ray absorption fine structure(XAFS) of the La K-edge. The nearest La$$^{3+}$$-Cl$$^-$$ distance andcoordination number were 2.89$$pm0.01$$${AA}$ and 7.4$$pm0.5$$ from the curve fitting of the 1st peak in the fourier transform magnitude $$|FT|$$. The coordination number larger than 6 suggests that the local structure of molten LaCl$$_3$$ is not a simple octahedral coordination (LaCl$$_6$$)$$^{3-}$$, but 7-fold (LaCl$$_7$$)$$^{4-}$$ and/or 8-fold (LaCl$$_8$$)$$^{5-}$$ complexes. The 1st La$$^{3+}$$-La$$^{3+}$$ distance, of which correlation was observed as a weak 2nd peak in the $$|FT|$$, was evaluated to be 4.9${AA}$. It suggests that the distorted corner-sharing connection of the complex species is predominant in the melt, inontrast with molten YCl$$_3$$ in which the edge-sharing connection of the 6-fold (YCl$$_6$$)$$^{3-}$$ mainly exists.

Journal Articles

Structural studies of lanthanide(III) complexes with oxydiacetic acid and iminodiacetic acid in aqueous solution by EXAFS

Narita, Hirokazu; Yaita, Tsuyoshi; Suzuki, Shinichi; Takai, Konomi; Tachimori, Shoichi; Motohashi, Haruhiko*

Journal of Synchrotron Radiation, 8(Part2), p.672 - 673, 2001/03

no abstracts in English

Journal Articles

Structural study on lanthanide complexes with tridentate ligands in solution

Narita, Hirokazu; Yaita, Tsuyoshi; Okamoto, Yoshihiro; Takai, Konomi; Shiwaku, Hideaki; Shimada, Asako*; Yamamoto, Takeshi*; Tanida, Hajime*

Spring-8 Experiment Report, Vol.6, P. 9, 2001/00

no abstracts in English

Journal Articles

Structural study of lanthanides(III) in aqueous nitrate and chloride solutions by EXAFS

Yaita, Tsuyoshi; Narita, Hirokazu*; Suzuki, Shinichi; Tachimori, Shoichi; Motohashi, Haruhiko; Shiwaku, Hideaki

Journal of Radioanalytical and Nuclear Chemistry, 239(2), p.371 - 375, 1999/00

 Times Cited Count:87 Percentile:98.33(Chemistry, Analytical)

no abstracts in English

Journal Articles

Structural study of holmium(III) and uranium(VI) organic ligand complexes by extended X-ray absorption fine-structure spectroscopy

Yaita, Tsuyoshi; Narita, Hirokazu*; Suzuki, Shinichi; Tachimori, Shoichi; Motohashi, Haruhiko; Shiwaku, Hideaki

Journal of Alloys and Compounds, 271-273, p.184 - 188, 1998/00

 Times Cited Count:16 Percentile:69.43(Chemistry, Physical)

no abstracts in English

Journal Articles

XAFS studies of uranium(VI) and thorium(IV)-amide and TBP complexes in ethanol solution

Yaita, Tsuyoshi; Narita, Hirokazu*; Suzuki, Shinichi; Shiwaku, Hideaki; Motohashi, Haruhiko; Ono, Hideo; Usami, Noriko*; Kobayashi, Katsumi*

Photon Factory Activity Report 1997, P. 81, 1997/00

no abstracts in English

Oral presentation

Introduction of the undulator Quick-XAFS system on BL11XU at SPring-8, and an application to Pd complex in the column chromatography

Shiwaku, Hideaki; Yaita, Tsuyoshi; Okamoto, Yoshihiro; Narita, Hirokazu*; Tanida, Hajime*

no journal, , 

no abstracts in English

Oral presentation

Extraction properties of lanthanides by various aromatic nitrogen ligands

Akutsu, Kazuhiro; Shiwaku, Hideaki; Okamoto, Yoshihiro; Suzuki, Shinichi; Ikeda, Atsushi; Kobayashi, Toru*; Numakura, Masahiko; Mahara, Saori*; Nakano, Yoshiharu*; Fujii, Yuki*; et al.

no journal, , 

no abstracts in English

Oral presentation

X-ray scattering study of microscopic structure for platinum group ions in solvent extraction

Motokawa, Ryuhei; Suzuki, Shinichi; Yaita, Tsuyoshi; Narita, Hirokazu*; Tanaka, Mikiya*

no journal, , 

no abstracts in English

25 (Records 1-20 displayed on this page)