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Journal Articles

Extended X-ray absorption fine structure study on gel/liquid extraction of f-block elements

Nakase, Masahiko*; Kobayashi, Toru; Shiwaku, Hideaki; Kawamura, Takuya*; Takeshita, Kenji*; Yamamura, Tomoo*; Yaita, Tsuyoshi

Progress in Nuclear Science and Technology (Internet), 5, p.56 - 60, 2018/11

Gel/liquid extraction was investigated to achieve selective separation of trivalent actinides over lanthanides. In this study, thermosensitive hydrogel including N,N,N',N'-tetraallylpyridine-2,6-dicarboxamine (PDA) was synthesized, and its complexation with lanthanide was investigated by extended X-ray absorption fine structure experiments at SPring-8. The radial structure functions (RSF) of solution with gels with and without ligands at different temperatures showed slight differences. As the temperature increased, the RSF decreased owing to the increase in thermal vibration, but PDA-gel showed a shift in the first peak toward the shorter direction. This shift was attributed to the change in stoichiometry of PDA-Ln(III) complexes or coordination number of water molecules affected by the change of conformation of polymer chains and the hydrophilic/hydrophobic properties in the hydrogel.

Journal Articles

Adsorption of platinum-group metals and molybdenum onto aluminum ferrocyanide in spent fuel solution

Onishi, Takashi; Sekioka, Ken*; Suto, Mitsuo*; Tanaka, Kosuke; Koyama, Shinichi; Inaba, Yusuke*; Takahashi, Hideharu*; Harigai, Miki*; Takeshita, Kenji*

Energy Procedia, 131, p.151 - 156, 2017/12

 Times Cited Count:3 Percentile:5.23

no abstracts in English

Journal Articles

Structure and complexation studies on 2,2'-bipyridyl and trivalent lanthanides

Nakase, Masahiko*; Takeshita, Kenji*; Kobayashi, Toru; Shiwaku, Hideaki; Yaita, Tsuyoshi

Separation Science and Technology, 50, p.2832 - 2835, 2015/05

 Times Cited Count:1 Percentile:91.43(Chemistry, Multidisciplinary)

Separation of trivalent lanthanides (Ln) and trivalent actinides (An) is important task in reprocessing high-level liquid waste. In this study, the relationship between structures of complexes of 2,2'-bipyridyl (Bpy) and Ln and coordination strengths were investigated by X-ray diffraction and UV titration. With the decrease in ionic radius from Nd to Er, the N(Bpy)-Ln distance and N(Bpy)-Ln-N(Bpy) angle decreased, the dihedral angle of the Bpy pyridines increased, and the stability constant increased. This information about structure and coordination strength is important for designing better ligands for separating Ln and An ions.

Journal Articles

Recovery of minor actinides from spent fuel using TPEN-immobilized gels

Koyama, Shinichi; Suto, Mitsuo; Obayashi, Hiroshi; Oaki, Hiroshi*; Takeshita, Kenji*

Proceedings of International Nuclear Fuel Cycle Conference; Nuclear Energy at a Crossroads (GLOBAL 2013) (CD-ROM), p.549 - 553, 2013/09

A series of separation experiments was performed in order to study the recovery process for minor actinides (MAs) from the actual spent fuel by using an extraction chromatographic technique. The 10 mol% TPPEN-gel was used to improve adsorption coefficient of Am and a condition of eluent temperature was changed in order to confirm the temperature swing effect on TPEN-gel for MA. More than 90% Eu was detected in the eluent after washing with 0.01M NaNO$$_{3}$$ (pH 3.5) at 5$$^{circ}$$C. Americium was backwardly detected and eluted continuously during in the same condition. After removal of Eu, the eluent temperature was changed to 32$$^{circ}$$C, then Am was detected (pH 3.0). Finally remained Am could be stripped from TPPEN-gel by changing the pH of the eluent to 2.0.

Journal Articles

Recovery of minor actinides from spent fuel via an extraction chromatographic technique using TPPEN-immobilized gels

Koyama, Shinichi; Suto, Mitsuo; Obayashi, Hiroshi; Takeshita, Kenji*; Ogata, Takeshi*; Oaki, Hiroshi*; Inaba, Yusuke*

Separation Science and Technology, 47(14-15), p.2024 - 2028, 2012/11

 Times Cited Count:2 Percentile:85.46(Chemistry, Multidisciplinary)

A series of separation experiments was performed to study the recovery process for minor actinides (MAs) from the actual spent fuel by using an extraction chromatographic technique. TPPEN gel was used as a new extraction chromatographic agent. Mixed oxide fuel was used as a reference spent fuel to demonstrate the recovery of the MAs. The MOX fuel, including 29.9 wt% plutonium (Pu), was irradiated up to 119 GWd/MTM, and the fuel was then prepared for the extraction experiment. A Mixed solution of MAs and lanthanides (Lns) was prepared. The TPPEN gel was immersed in a 0.01 M NaNO$$_{3}$$ solution, and the pH was adjusted to 4.0. Next, an extraction column was prepared using the TPPEN gel, and the mixed solution of MAs and Lns was passed through the column. The Lns were detected in the eluent after washing with 0.01 M NaNO$$_{3}$$ (pH 4.0). For detecting the MAs, the pH of the eluent was changed to 2.0.

Journal Articles

Thermoresponsive extraction of cadmium(II) ions by poly(TPEN-NIPA) gels; Effect of chain length and branched spacer structure on gel formation and extraction behavior

Inaba, Yusuke*; Tsumagari, Takayuki*; Kida, Tatsuya*; Watanabe, Wataru*; Nakajima, Yasutaka*; Fukuoka, Sachio*; Mori, Atsunori*; Matsumura, Tatsuro; Nakano, Yoshio*; Takeshita, Kenji*

Polymer Journal, 43(7), p.630 - 634, 2011/07

 Times Cited Count:10 Percentile:58.08(Polymer Science)

${it N,N,N',N'}$-(tetrakis-2-pyridylmethyl)ethylenediamine (TPEN) derivatives bearing a polymerizable double bond in the substituent structure of the pyridine ring are synthesized and subjected to copolymerization with ${it N}$-isopropylacrylamide in the presence of AIBN. The obtained poly(TPEN-NIPA) gels show thermo-responsive swelling/shrinking behaviors and are employed for the extraction of cadmium(II) ion from the aqueous solution to examine the relationship of the gel characteristics and the extraction performance. The polymer gels composed of the TPEN derivative bearing C3, C4, C10 and branched C3 spacer chains are synthesized and temperature-dependent extraction behavior of cadmium ion is compared. These gels extract Cd(II) ion efficiently from the aqueous solution in the swelling state at 5$$^{circ}$$C, while little extraction is observed at 45$$^{circ}$$C with shrinking. It is found that poly(TPEN-NIPA) gel of branched C3 spacer (C3b) shows the excellent thermoresponsive extraction performance.

Journal Articles

Am/Eu separation with a new ligand, N,N,N',N'-tetrakis((4-butoxypyridin-2-yl)methyl)ethylenediamine (TBPEN), a hydrophobic derivative of TPEN

Matsumura, Tatsuro; Inaba, Yusuke*; Mori, Atsunori*; Takeshita, Kenji*

Journal of Nuclear Science and Technology, 47(2), p.123 - 126, 2010/02

 Times Cited Count:10 Percentile:34.14(Nuclear Science & Technology)JP, 2007-210038   Patent publication (In Japanese)

We are developing a new MA/Ln separation process with TPEN and its derivatives for P&T technology. TPEN is a hexadentate soft-donor ligand that has six soft-donor sites as a kind of podand type molecule and can encapsulate a metal ion. TPEN has good selectivity of Am(III) from Ln(III) and has potential to establish partitioning of MA. From the viewpoint of practical application, the hydrophobicity of TPEN must be improved. Because the dissolution of a slight amount of TPEN (about 10$$^{-4}$$ mol/l) to water will restrict decontamination of Ln in extraction process. In this study, the hydrophobicity of TPEN was improved by introducing alkyl groups and the effect of the introduction of alkyl groups on the separation of Am(III) and Eu(III) was examined. One of them, N,N,N',N'-tetrakis((5-butoxypyridin-2-yl)-methyl)ethylenediamine, TBPEN, showed good selectivity and the maximum separation factor, SF$$_{Am/Eu}$$, was 91 at pH 3.02. The hydrophobicity of TBPEN is checked by the distribution data between water and chloroform, and improved successfully. The approach for development of hydrophobic derivatives of TPEN was effective.

Journal Articles

Thermo-responsive extraction of cadmium(II) ion with TPEN-NIPA gel; Effect of the number of polymerizable double bond toward gel formation and the extracting behavior

Fukuoka, Sachio*; Kida, Tatsuya*; Nakajima, Yasutaka*; Tsumagari, Takayuki*; Watanabe, Wataru*; Inaba, Yusuke*; Mori, Atsunori*; Matsumura, Tatsuro; Nakano, Yoshio*; Takeshita, Kenji*

Tetrahedron, 66(9), p.1721 - 1727, 2010/02

 Times Cited Count:16 Percentile:47.33(Chemistry, Organic)

N,N,N',N'-(tetrakis-2-pyridylmethyl)ethylenediamine (TPEN) derivatives bearing the different number (1-4) of a double bond moiety on the pyridine ring are synthesized and subjected to copolymerization with N-isopropylacrylamide in the presence of AIBN. The obtained poly(TPEN-NIPA)gels show thermo-responsive swelling/shrinking behaviors and are employed for the extraction of cadmium(II) ion from the aqueous solution to examine the relationship of the gel characteristics and the extraction performance. The polymer gels composed of the TPEN derivative bearing three or four double bonds exhibit temperature-dependent change of swelling and shrinking in water. These gels extract CdII ion efficiently from the aqueous solution in the swelling state at 5$$^{circ}$$C, while little extraction was observed at 45$$^{circ}$$C with shrinking.

Journal Articles

AM(III)/EU(III) separation with hydrophobic alkylated TPEN

Matsumura, Tatsuro; Takeshita, Kenji*; Inaba, Yusuke*; Mori, Atsunori*

Proceedings of 10th OECD/NEA Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation (CD-ROM), 6 Pages, 2010/00

JP, 2007-210038   Patent publication (In Japanese)

no abstracts in English

Journal Articles

Advanced hydrometallurgical separation of actinides and rare metals in nuclear fuel cycle

Ozawa, Masaki; Suzuki, Shinichi; Takeshita, Kenji*

Solvent Extraction Research and Development, Japan, 17, p.19 - 34, 2010/00

A hydrometallurgical separation technologies by novel solvent extraction (SX), ion exchange chromatography (IXC) and electrolytic extraction techniques are reviewed as separation tools for light PGM (Ru, Rh, Pd), Tc and $$f$$-elements in high level liquid wastes of the nuclear fuel cycle. The SX process using N,N-dialkylamide can isolate U(VI) from fission products without Pu(IV) valence control, and extractants with soft-hard hybrid donors (PTA and PDA) and those containing six soft donors (TPEN) show good separation of actinides (III) from lanthanides (III). The catalytic electrolytic extraction (CEE) process utilizing Pd$$_{it adatom}$$ or Rh$$_{it adatom}$$ can effectively separate platinum group metals (PGM), Tc and Re by means of controlled under potential deposition (UPD). Some of the basic work on the hydrometallurgical separation of the elements of interest has been carried out through the strategic Advanced (Adv.-) ORIENT Cycle research in Japan.

Journal Articles

${it N,N,N',N'}$-tetrakis((5-alkoxypyridin-2-yl)methyl)ethylenediamine, TRPEN, effective ligands for the separation of trivalent minor actinides from lanthanides

Matsumura, Tatsuro; Inaba, Yusuke*; Koma, Yoshikazu; Morita, Yasuji; Mori, Atsunori*; Takeshita, Kenji*

Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.1107 - 1112, 2009/09

JP, 2007-210038   Patent publication (In Japanese)

no abstracts in English

Journal Articles

Am(III)/Eu(III) separation with hydrophobic derivatives of TPEN

Matsumura, Tatsuro; Inaba, Yusuke*; Takeshita, Kenji*; Mori, Atsunori*

Proceedings of International Solvent Extraction Conference "Solvent Extraction-Fundamentals to Industrial Applications" (ISEC 2008), 4 Pages, 2008/09

JP, 2007-210038   Patent publication (In Japanese)

We are developing a new MA/Ln separation process with derivatives of TPEN (N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine) for P&T technology. TPEN has good selectivity of Am(III) from Ln(III). However, TPEN is soluble slightly (about 10$$^{-4}$$ mol/l) to water. In this study, the hydrophobicity of TPEN is improved by introducing alkyl groups and the selectivity of Am(III) and Eu(III) is examined. We succeeded to synthesize several new hydrophobic derivative of TPEN. One of the ligands, TDdPEN (N,N,N',N'-tetrakis((5-dodecyloxypyridin-2-yl)-methyl)ethylenediamine) showed high selectivity. The maximum separation factor, SF$$_{Am/Eu}$$, was over 800. Hydrophobic derivatives of TPEN that have potential of application to the MA/Ln separation process was synthesized successfully.

Journal Articles

Separation of americium(III) and lanthanide(III) ions using TPEN analogs

Fugate, G.*; Takeshita, Kenji*; Matsumura, Tatsuro

Separation Science and Technology, 43(9&10), p.2619 - 2629, 2008/07

The compound N,N,N',N'-tetrakis(methylpyridyl)-1,2-ethylenediamine (TPEN) has been shown previously to exhibit a high separation factor for the separation of americium(III) and europium(III) but the application of this material to the nuclear fuel cycle is limited because of pH range of the separation (pH3 to 6) and the high solubility of the compound in acidic aqueous media. A variety of compounds have been synthesized during the course of this study in an attempt to retain the separation factor found in the parent compound while decreasing the working pH and aqueous solubility of the extractant. A series of compounds was synthesized in which the ethylene linker was replaced by several aromatic compounds. Another series of analogs was synthesized replacing two or more of the methylpyridyl groups with several different functional moieties. The separation properties of these new compounds were characterized and will be presented.

Journal Articles

MA/Ln separation with new ligand, hydrophobic derivatives of TPEN

Matsumura, Tatsuro; Takeshita, Kenji*; Mori, Atsunori*

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 4 Pages, 2008/05

JP, 2007-210038   Patent publication (In Japanese)

We are developing a new MA/Ln separation process with derivatives of TPEN (N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine) for P&T technology. TPEN is a hexadentate ligand, which has good selectivity of Am(III) from Ln(III). However, there is a serious problem for the practical application. This is to the dissolution of a slight amount of TPEN (about 10$$^{-4}$$ mol/l) to water. High enrichment of Am(III) will be restricted by the dissolution of TPEN to water. In this study, the hydrophobicity of TPEN is improved by introducing alkyl groups and the selectivity of Am(III) and Eu(III) is examined. We succeeded to synthesize a new hydrophobic derivative of TPEN, TBPEN (N,N,N',N'-tetrakis((5-butoxypyridin-2-yl)-methyl)ethylenediamine. It showed good selectivity and the maximum separation factor, SF$$_{rm Am/Eu}$$, was 91 at pH 3.0. A hydrophobic derivative of TPEN that has potential of application to the MA/Ln separation process was synthesized successfully.

Journal Articles

Extraction separation of Am(III) and Eu(III) with thermosensitive gel introducing TPEN derivatives

Takeshita, Kenji*; Nakano, Yoshio*; Matsumura, Tatsuro; Mori, Atsunori*

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 8 Pages, 2008/05

A thermal-swing chromatographic process using a thermosensitive gel copolymerized with NIPA (N-isopropylacrylamide) and TPPEN (N,N,N',N'-tetrakis(4-propenyloxy-2-pyridylmethyl)ethylenediamine) was studied for the separation of Am(III) from Eu(III). Firstly, the radiolysis of the TPPEN-NIPA gel was tested by the $$gamma$$-ray irradiation and the $$alpha$$ nuclide adsorption. The extraction separation of Am(III) was not influenced in the radioactive environment of the proposed process. Next, the TPPEN-NIPA gel was immobilized in porous silica particles and the applicability of the gel-immobilized silica to the proposed process was tested. Am(III) was extracted selectively in the gel-immobilized silica at 5$$^{circ}$$C and the separation factor of Am(III) over Eu(III) was evaluated to be 3.7. The distribution ratio of Am(III) was reduced to less than 1/20 by increasing temperature from 5$$^{circ}$$C to 40$$^{circ}$$C. These results indicate that the TPPEN-NIPA gel is applicable to the thermal-swing chromatographic process for the MA recovery.

Journal Articles

Extraction separation of trivalent minor actinides from lanthanides with hydrophobic derivatives of TPEN

Matsumura, Tatsuro; Takeshita, Kenji*

Progress in Nuclear Energy, 50(2-6), p.470 - 475, 2008/03

 Times Cited Count:9 Percentile:39.3(Nuclear Science & Technology)

We are developing a new MA/Ln separation process with TPEN and its derivatives for P&T technology. TPEN is a hexadentate ligand and a kind of podand type molecule and can encapsulate a metal ion. TPEN has good selectivity of Am(III) from Ln(III) and has potential to establish partitioning of MA. However, there is a serious problem for the practical application. This is to the dissolution of a slight amount of TPEN to water. High enrichment of Am(III) will be restricted by the dissolution of TPEN to water. In this study, the hydrophobicity of TPEN is improved by introducing alkyl groups and the effect of the introduction of alkyl groups on the separation of Am(III) and Eu(III) is examined. We synthesized three derivatives successfully. The derivatives were examined both the extractability and selectivity of Am(III) and Eu(III). One of them, tpdben, showed good selectivity and the maximum separation factor, SF$$_{rm Am/Eu}$$, was 35 at pH 5.06. A hydrophobic derivative of TPEN that has potential of application to the MA/Ln separation process was synthesized successfully.

Journal Articles

Thermal-swing extraction separation of Am(III) and Eu(III) with poly-NIPA gel crosslinked with TPEN derivative

Takeshita, Kenji*; Matsumura, Tatsuro; Nakano, Yoshio*

Journal of Nuclear Science and Technology, 44(12), p.1481 - 1483, 2007/12

 Times Cited Count:6 Percentile:51.27(Nuclear Science & Technology)

The extraction separation of trivalent minor actinides from lanthanides was examined by a thermosensitive gel, poly-NIPA (N-isopropyl acrylamide) crosslinked with a TPEN derivative, N,N,N',N'-tetrakis(4-propenyloxy-2-pyridylmethyl)ethylenediamine (tppen). The synthesized gel showed the conformational change of polymer network with temperature, which is known as the phase transition phenomena of gel, and such conformational change was repeated stably by the thermal-swing operation between 5$$^{circ}$$C and 40$$^{circ}$$C. Then, Am(III) was extracted selectively in the swollen gel at 5$$^{circ}$$C and released easily from the shrunken gel at 40$$^{circ}$$C. The distribution ratio of Am(III) and the separation factor between Am(III) and Eu(III) were evaluated as 2000 and 18 in the swollen gel. These values are sufficient to the establishment of a practical MA recovery process. Then, both the extractability and selectivity of Am were maintained stably and the selective extraction of Am was attainable by the simple thermal-swing operation. These results suggest that the proposed gel extraction process is applicable to a MA partitioning for transmutation.

Journal Articles

Separation of Actinide(III) from Lanthanide(III) by thermosensitive gel copolymerized with TPEN derivatives

Takeshita, Kenji*; Fugate, G.*; Matsumura, Tatsuro; Nakano, Yoshio*; Mori, Atsunori*; Fukuoka, Sachio*

Proceedings of International Conference on Advanced Nuclear Fuel Cycles and Systems (Global 2007) (CD-ROM), p.120 - 125, 2007/09

Extraction separation of Am(III) and Eu(III) was examined by the thermal-swing extraction technique using a thermosensitive gel, poly-$$N$$-isopropylacrylamide (NIPA) copolymerized with a TPEN derivative, $$N,N,N',N'$$-tetrakis(4-propenyloxy-2-pyridylmethyl)ethylenediamine (TPPEN). The separation of Am(III) from Eu(III) was observed in the swollen state of gel (5$$^{circ}$$C) and the separation factor of Am(III) was evaluated as about 18 at pH5.2. More than 90% of Am(III) extracted into the gel was released by the volume phase transition of gel from the swollen state (5$$^{circ}$$C) to the shrunken one (40$$^{circ}$$C). The repetition test for the thermal swing extraction of a soft metal ion, Cd(II), which was used as a substitute of Am(III), was carried out and the extraction and release of Cd(II) were repeated three times stably under the thermal-swing operation between 5$$^{circ}$$C and 40$$^{circ}$$C. The radiation effect of gel on the extraction of Am and Eu was tested by the irradiation of $$gamma$$-ray (10 kGy) and the long-term adsorption of $$alpha$$-emitter ($$^{244}$$Cm). The TPPEN-NIPA gel sustained no damage by these radiation tests. These results suggest that the thermal-swing extraction technique is applicable to the MA partitioning process indispensable for the establishment of P&T technology.

Journal Articles

Thermal-swing extraction of Cadmium(II) by thermosensitive polymer gel crosslinked with Encapsulating hexadentate ligand

Takeshita, Kenji*; Ishida, Keigo; Nakano, Yoshio*; Matsumura, Tatsuro

Chemistry Letters, 36(8), p.1032 - 1033, 2007/08

 Times Cited Count:20 Percentile:40.59(Chemistry, Multidisciplinary)

Thermal-swing extraction of Cd(II) with a thermosensitive gel, poly-N-isopropylacrylamide (NIPA) crosslinkedwith a podand, N,N,N',N'-tetrakis(4-propenyl-oxy-2-pyridylmethyl)ethylenediamine (TPPEN), was examined. Cd(II) was extracted selectively in the gel swollen at 5$$^{circ}$$C andreleased from the gel shrunken at 40$$^{circ}$$C. The difference in thedistribution ratios of Cd(II) between these temperatures wasmore than 30 times.

Journal Articles

Am(III)/Eu(III) separation with TPEN

Matsumura, Tatsuro; Takeshita, Kenji*

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 5 Pages, 2007/04

We are developing a new MA/Ln separation process with TPEN derivatives for P&T technology. TPEN is a hexadentate ligand and a kind of podand type molecule and can encapsulate a metal ion. TPEN has good selectivity of Am(III) from Ln(III). However, there is a serious problem for the practical application. This is to the dissolution of a slight amount of TPEN to water. In this study, the hydrophobicity of TPEN is improved by introducing alkyl groups and the effect of the introduction of alkyl groups on the separation of Am(III) and Eu(III) is examined. We synthesized three derivatives successfully. The derivatives were examined both the extractability and selectivity of Am(III) and Eu(III). One of them, tpdben, showed good selectivity and the maximum separation factor, SF$$_{Am/Eu}$$, was 35 at pH 5.06. A hydrophobic derivative of TPEN that has potential of application to the MA/Ln separation process was synthesized successfully.

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