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-hexaoctyl nitrilotriacetamide (HONTA) using mixer-settler extractors in a hot cellBan, Yasutoshi; Suzuki, Hideya*; Hotoku, Shinobu; Tsubata, Yasuhiro
Solvent Extraction Research and Development, Japan, 31(1), p.1 - 11, 2024/00
A demonstration test was performed to separate minor actinides (MA; Am and Cm) by -hexaoctyl nitrilotriacetamide (HONTA) as an extractant using mixer-settler extractors installed in a hot cell. A high-level liquid waste containing MA, and rare earths (RE; Y, La, Nd, and Eu) was used as the feed. HONTA diluted to 0.05 mol/dm
in 
-dodecane was fed as the organic phase, and a part of the organic phase was reused without solvent regeneration. HONTA effectively extracted MA, whereas RE were less extractable. Consequently, the Y, La, Nd, and Eu ratios distributed to a RE fraction were 
99.9%, 99.2%, 61.8%, and 81.4%, respectively. The Am and Cm ratios distributed to an MA fraction were 86.8% and 74.7%, respectively, and a substantial amount of MA (0.12 g) was recovered in the MA fraction by the end of the cumulative duration of 40 h.
Uchino, Seiko*; Narita, Hirokazu*; Kita, Keisuke*; Suzuki, Hideya*; Matsumura, Tatsuro; Naganawa, Hirochika*; Sakaguchi, Koichi*; Oto, Keisuke*
Solvent Extraction Research and Development, Japan, 30(1), p.39 - 46, 2023/00
The extraction of trivalent rare earth ions (RE
) from HNO
solution using a triamide amine, tris(N,N-di-2-ethylhexyl-ethylamide)amine (DEHTAA), was conducted, and the extraction mechanism was estimated from extraction behavior of HNO and RE and the relationship between atomic number and extraction percentages (E%) for RE. A DEHTAA molecule dominantly formed a DEHTAA HNO at 1.0 M HNO and a DEHTAA(HNO)
at 6.0 M HNO in the acid-equilibrated organic phase. This would provide the unique dependence of E% for the light RE on the HNO concentration, in which the E% value had a minimum and maximum at 
0.5 M and 2 M HNO, respectively. The results of the slope analyses for the distribution ratios for RE suggested that the dominant RE complex was RE(NO)DEHTAA(DEHTAA HNO) at 1.0 M HNO. The E% for RE decreased from La to Lu at 1.0 M HNO; on the other hand, those increased from La to Nd at 0.25 M and from La to Sm and 6.0 M HNO.
Matsumura, Tatsuro
Kino Zairyo, 40(1), p.60 - 71, 2020/01
no abstracts in English
Kaneko, Masashi; Suzuki, Hideya; Matsumura, Tatsuro
Inorganic Chemistry, 57(23), p.14513 - 14523, 2018/12
Times Cited Count：20 Percentile：78.15(Chemistry, Inorganic & Nuclear)We elucidated the separation mechanism between Am(III) and Cm(III) ions by using two different types of diamide ligands, diglycolamide (DGA) and alkylated diamide amine (ADAAM), by means of the density functional theory technique and electron density analysis. The molecular geometries and formation reactions of the metal-ligand complexes were modeled by using [M(DGA)] and [M(ADAAM)(NO)(HO)]. We successfully reproduced Cm(III) selectivity over Am(III) with DGA and Am(III) selectivity over Cm(III) with ADAAM. Furthermore, we analyzed the bonding properties between the metal ion and the diamide-type ligands by using model complexes, [M(DGA)] and [M(ADAAM)(NO)(HO)], and revealed the differences in terms of the bond dissociation energy and the metal 5f-orbital participation in the covalency between the Am(III) and the Cm(III) complexes. It was suggested that the differences were key factors to understand the Am(III)/Cm(III) selectivity.
Kimura, Taiki*; Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*
Dalton Transactions (Internet), 47(42), p.14924 - 14931, 2018/11
Times Cited Count：9 Percentile：49.17(Chemistry, Inorganic & Nuclear)We demonstrated density functional calculations of Eu(III) and Am(III) complexes with pnictogen-donor (X) ligands, CH)X-CH-CH-X(CH) (X = N, P, As and Sb). We investigated the optimized structures of the cmoplexes and the Gibbs energy differences in the complex formation reactions. Those results indicated that the N- and P-donor ligands have Am(III) ion selectivity over Eu(III) ion, especially, the P-donor ligand showed the highest selectivity. The tendency of the Am(III)/Eu(III) selectivity by the pnictogen-dono ligands was found to be comparable to that of soft acid classification in hard and soft acids and bases rule. Mulliken's spin population analysis indicated that the bonding property between the metal ion and the pnictogen atoms correlated with the Am(III)/Eu(III) selectivity. In particular, the participation of f-orbital electrons of the metal ion in the covalency was indicated to have an important role for the selectivity.
Takahatake, Yoko; Watanabe, So; Kofuji, Hirohide; Takeuchi, Masayuki; Nomura, Kazunori; Sato, Takahiro*
International Journal of PIXE, 26(3&4), p.73 - 83, 2017/09
JAEA has been conducting research and development of MA(III) recovery from HLLW by extraction chromatography technology for reduction in amount and environmental impact of radioactive waste. The behavior of adsorbed cations inside the adsorbent packed in a column is necessary to be evaluated for improvement of the adsorbent or flow-sheet to achieve targeted MA(III) recovery performance. In this paper, micro-PIXE analysis was carried out on the particles sampled from various positions of the column to reveal the behavior of cations inside the packed column with CMPO/SiO -P adsorbent. Simple experiment and data analysis were shown to be effective to reveal inside of the column, and formation and transportation of the adsorption bands were observed for some cations which are extractable by the CMPO extractant. Some part of Zr(IV) and Mo(VI) were found to remain inside the column without distinct transportation even after the elution operation.
Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*
Journal of Nuclear and Radiochemical Sciences (Internet), 17, p.9 - 15, 2017/03
Density functional calculations were applied to the complexation of Eu(III) and Am(III) ions with phosphinic acid (O-donor) and dihiophosphinic acid (S-donor) from the viewpoint of the bonding nature of valence orbitals in metal ion. Two and four conformers for S-donor and O-donor complexes, respectively were optimized. Their stabilization energies by complex formation toward [M(HO)
] were estimated. As the result, the energies reproduced the experimental Am(III)/Eu(III) selectivity that O-donor ligand preferably coordinates to Eu(III) ion, whereas S-donor ligand selectively coordinates to Am(III) ion. Focused on the bonding natures of d and f-orbital electrons, it was indicated that the d-orbital electrons in both Eu and Am complexes participate in the covalency as bonding-type nature and have the almost same contribution. Meanwhile, the contribution of the f-orbital electrons was different between Eu and Am complexes and indicated that in the case of S-donor complex, non-bonding type and bonding type contributions were observed for Eu and Am complexes, respectively and in the case of O-donor complex, bonding type and anti-bonding type contributions were observed for Eu and Am complexes, respectively. This result suggested that the bonding natures of d-orbital electrons contribute to the geometrical similarity of molecular structures for Eu and Am complexes and the bonding natures of f-orbital electrons contribute to the difference in the selectivity of Eu and Am ions.
Kaneko, Masashi; Watanabe, Masayuki; Matsumura, Tatsuro
Dalton Transactions, 45(43), p.17530 - 17537, 2016/11
Times Cited Count：33 Percentile：87.63(Chemistry, Inorganic & Nuclear)Relativistic density functional calculations were applied to study the separation behaviors of Am(III) ion from Eu(III) ion by diglycolamide (DGA) and nitrilotriacetamide (NTA) ligands in order to understand the difference in the separation mechanism of their reagents. The complexation reaction was modeled on the basis of previous experimental studies. The calculated energies based on stabilization by complex formation at the ZORA-B2PLYP/SARC level predicted that the DGA reagent preferably coordinated to Eu(III) ion when compared with Am(III) ion. In contrast, the NTA reagent selectively coordinated to Am(III) ion when compared with Eu(III) ion. These results reproduced the experimental selectivity of DGA and NTA ligands toward Eu(III) and Am(III) ions. Mulliken's population analyses implied that the difference in the contribution of the bonding property between the f-orbital of Am and donor atoms determined the comparative stability of Eu and Am complexes.
Matsumura, Tatsuro; Tsubata, Yasuhiro; Urabe, Shunichi; Shibata, Mitsunobu; Ichimura, Seiji; Hagiya, Hiromichi*; Tsujimoto, Kazufumi
no journal, ,
no abstracts in English
Matsumura, Tatsuro
no journal, ,
no abstracts in English
Matsumura, Tatsuro; Suzuki, Hideya; Tsubata, Yasuhiro; Shibata, Mitsunobu; Kurosawa, Tatsuya; Kawasaki, Tomohiro; Sagawa, Hiroshi
no journal, ,
no abstracts in English
Matsumura, Tatsuro; Suzuki, Hideya; Tsubata, Yasuhiro; Shibata, Mitsunobu; Kurosawa, Tatsuya; Kawasaki, Tomohiro; Sagawa, Hiroshi
no journal, ,
no abstracts in English
Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Hotoku, Shinobu; Tsutsui, Nao; Suzuki, Asuka
no journal, ,
The new reprocessing and minor actinide (MA) separation processes using innovative extractants in accord with CHON principle has been developed in Japan Atomic Energy Agency aimed for reduction of radioactive wastes from nuclear fuel cycle. The new nonorganophosphorus extractants which have appropriate extraction behaviors for each separation steps were developed. Continuous counter-current experiment of each solvent extraction process with uranium, plutonium and tracers of minor actinides were carried out. The experimental results showed that the separation performance of the solvent extraction processes were demonstrated successfully.
Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*
no journal, ,
To understand the separation mechanism of minor-actinides (MA) from lanthanides (Ln) is important for the development of partitioning and transmutation of high-level radioactive waste. We aim to discuss the bonding nature between MA/Ln ions and ligands with the separation behavior of MA from Ln, which leads to the elucidation of the selectivity of MA compared to Ln. In this study, we demonstrate the separation behavior of MA from Ln at molecular level by means of density functional calculations and discuss how the bonding properties of valence electrons contributes to the selectivity of MA.
Kaneko, Masashi; Watanabe, Masayuki; Miyashita, Sunao*; Nakashima, Satoru*
no journal, ,
In this study, we discussed the stability and bonding property of Eu and Am complexes with imidodiphosphinic acid which shows the same coordination geometry for both O- and S-donor ligands. We performed the geometry optimizations by referring to single crystal structures as their starting coordinates and calculated the Gibbs energy for the stabilization toward the hydrated complex. As the results, the calculated Eu and Am complexes have the same coordination geometries for O- and S-donor complexes and reproduced the metal-ligand distances of single crystal structures. The results of Gibbs energy indicated that O-donor preferably coordinates to Eu over Am, meanwhile, S-donor selectively coordinates to Am over Eu.
Suzuki, Hideya; Tsubata, Yasuhiro; Matsumura, Tatsuro
no journal, ,
Alkyl diamide amine (ADAAM) was investigated for the separation of MA(III). ADAAM is a multidentate ligand comprising one soft N-donor atom and two hard O-donor atoms as part of its central frame. This tridentate set of donor atoms provide selective binding for Am(III) and Cm(III) in highly acidic media and yield separation factors of up to 5.5. A continuous liquid-liquid extraction and stripping test was performed using ADAAM(EH) in n-dodecane as the extractant in a multistage countercurrent mixer-settler extractor. Separation of Am(III) and Cm(III) in very high yield was demonstrated.
Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Toigawa, Tomohiro; Tsutsui, Nao; Hotoku, Shinobu; Suzuki, Asuka
no journal, ,
no abstracts in English
Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Hotoku, Shinobu; Tsutsui, Nao; Suzuki, Asuka; Toigawa, Tomohiro; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; et al.
no journal, ,
To continue the utilization of the nuclear fission energy, the management of the high-level radioactive waste is one of the most important issues to be solved. Partitioning and Transmutation technology is expected to be effective to mitigate the burden of the HLW disposal by reducing the radiological toxicity and heat generation. JAEA has been conducting R&D on the MA separation process to remove of MA from HLW and supply the recovered MA to the transmutation system such as ADS. The MA separation process contains three steps. For An(III)+RE recovery process, we developed TDdDGA which has very high performance to recover of MA from high level waste. HONTA and ADAAM were developed for An(III)/RE separation process and Am/Cm separation process respectively. All extractants satisfy CHON principle to minimization of the secondary waste from the process. The separation performances of the flowsheets were evaluated by continuous extraction tests using simulated and genuine high level liquid waste.
Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Hotoku, Shinobu; Tsutsui, Nao; Suzuki, Asuka; Toigawa, Tomohiro; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; et al.
no journal, ,
PUREX process was established for industrial scale reprocessing plant. TRUEX and the 4 group separation were developed for partitioning of minor actinides from HLW, and demonstrated using genuine HLW. Although the extractants for the processes have excellent performance, the molecules contain phosphorus which could be cause for the secondary waste from the solvent extraction processes. To minimize the radioactive waste, we have conducted research and development of the new reprocessing and MA separation processes using innovative extractants in accord with CHON principle. The extractants for reprocessing process are monoamides as alternative extractants for TBP. For An(III)+RE recovery process, we developed TDdDGA. HONTA and ADAAM were developed for An(III)/RE separation process and Am/Cm separation process respectively. The separation performances of the flowsheets were evaluated by continuous extraction tests using simulated and genuine spent fuel and high level liquid waste.
Suzuki, Hideya; Tsubata, Yasuhiro; Ban, Yasutoshi; Shibata, Mitsunobu*; Kurosawa, Tatsuya*; Kawasaki, Tomohiro*; Matsumura, Tatsuro
no journal, ,
The authors have developed a new extractant for the separation of minor actinide (MA) from high-level liquid waste (HLLW). Tetra-2-ethylhexyldiglycolamide (TEHDGA) has four branched alkyl chains and has high solubility in diluents. Furthermore, TEHDGA has high selectivity of MA from fission products, high extraction capacity, fast extraction kinetics, fast phase separation, and low cost. TEHDGA is a highly practical extractant for partitioning MA from HLLW.
