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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:0 Percentile:100(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

 Times Cited Count:2 Percentile:51.88(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:3 Percentile:68.46(Chemistry, Analytical)

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:7 Percentile:41.84(Engineering, Chemical)

Journal Articles

Development of new type passive autocatalytic recombiner, 1; Experimental study on degradation of catalyst

Kamiji, Yu; Matsumura, Daiju; Taniguchi, Masashi*; Nishihata, Yasuo; Tanaka, Hirohisa*; Hirata, Shingo*; Hara, Mikiya; Hino, Ryutaro

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 4 Pages, 2015/05

In a severe accident at a nuclear power plant, a large amount of hydrogen can be released to primary containment vessel or reactor building. Passive autocatalytic recombiner (PAR) is one of the most effective systems for hydrogen mitigation and safety accident management. The new type PAR is under developing to improve conventional PARs, especially its size and weight. In this study, the influence of steam coexistence for the automotive catalyst activity was experimentally examined. These results show that the steam slightly affects the reaction start up and catalyst activity.

Journal Articles

Development of new type passive autocatalytic recombiner, 1; Characterization of monolithic catalyst

Kamiji, Yu; Taniguchi, Masashi*; Nishihata, Yasuo; Nagaishi, Ryuji; Tanaka, Hirohisa*; Hirata, Shingo*; Hara, Mikiya; Hino, Ryutaro

Proceedings of 2nd International Conference on Maintenance Science and Technology (ICMST-Kobe 2014), p.87 - 88, 2014/11

For hydrogen mitigation, a new type passive autocatalytic recombiner is under development. In this study, the activation energy of hydrogen-oxygen recombination reaction was examined to clarify the basic characteristics of the catalyst. In addition, the degradation of the catalyst by $$gamma$$-ray irradiation simulating the environmental condition in nuclear power plants was also examined. As a result, the activation energy was experimentally estimated at 5.75 kJ/mol. Besides, no significant differences were observed in the compositional distribution from the EPMA results between the non-irradiated and the irradiated catalyst. However, the irradiated catalyst showed much more activity because of larger specific surface area of the catalyst and surface area of the precious metals. It showed that $$gamma$$-ray irradiation up to 1.0 MGy can increase activity of the catalyst.

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

Oral presentation

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

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

no journal, , 

no abstracts in English

Oral presentation

Neutron 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

Oral presentation

Neutron scattering study of microscopic structure for platinum group ions in solvent extraction

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

no journal, , 

no abstracts in English

Oral presentation

Application of solvent extraction to the recycling process of electroless nickel plating baths

Naganawa, Hirochika; Tanaka, Mikiya*; Saki, Yukinori*

no journal, , 

Electroless nickel plating is an important surface finishing technology; however, the treatment of a large amount of spent baths should be established from both the environmental and economic viewpoints. Solvent extraction is a useful separation technology which utilizes the distribution of a solute between aqueous and organic phases. The present authors have developed a nickel recycling process from the spent baths using solvent extraction. This process was applied to a plating plant initially using a conventional mixer-settler and then a new apparatus called emulsion flow extractor. In this presentation, the laboratory-scale experimental results and practical operation data will be presented.

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