Tatsuro Matsumura

Extraction Behavior of Am(III) from Eu(III) with Hydrophobic Derivatives of N,N,N',N'-tetrakis(2-methylpyridyl)ethylenediamine (TPEN)

Reduction of radioactive toxicity of HLW is very important to decrease the risk of the environmental impact of nuclear wastes disposed to deep underground. The technique for the improvement of hydrophobicity of TPEN, which is one of properties that should be solved to construct MA/lanthanides separation process, is elucidated

The separation mechanism of Am(III) from Eu(III) by diglycolamide and nitrilotriacetamide extraction reagents using DFT calculations

Relativistic density functional calculations were applied to study the separation behaviors of the Am(iii) ion from the 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 the Eu(iii) ion when compared with the Am(iii) ion. In contrast, the NTA reagent selectively coordinated to the Am(iii) ion when compared with the Eu(iii) ion. These results reproduced the experimental selectivity of DGA and NTA ligands toward Eu(iii) and Am(iii) ions. Mullikens 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.

Separation of Trivalent Minor Actinides from Fission Products Using Single R-BTP Column Extraction Chromatography

As part of the Fast Reactor Cycle Technology Development (FaCT) Project, research and development has been underway on a system for reprocessing spent fuel from fast breeder reactors. In this system, the method of extraction chromatography is used to recover minor trivalent actinides (MA(III) = Am(III) + Cm(III)) from acidic raffinate in the solvent extraction process that recovers U, Np, and Pu. In general, extractants for solvent extraction can be used as impregnated adsorbents for the extraction chromatography system. The principle of separation used in extraction chromatography is similar to that of solvent extraction. Because of the similarity in chemical properties between MA(III) and Lanthanides(III), MA(III) recovery processes using solvent extraction consist of two steps, namely, MA(III) Ln(III) recovery and MA(III)/Ln(III) separation. Of these, MA(III)/ Ln(III) separation is one of the most challenging issues. Since nitrogen and sulfur donors bind more readily to MA(III) than to Ln(III), a large number of N-donor extractants have been developed in many research projects. Kolarik et al. have reported that a new N-donor ligand, 2,6-bis(5,6-dialkyl-1,2,4-triazine-3-yl)pyridine (R-BTP), shows high selectivity for MA(III) over Ln(III). To develop a partitioning process using the extraction chromatography technique, Wei et al. reported an excellent adsorbent for extraction chromatography. The support particle for the adsorbent consisted of porous silica supports coated with styrenedivinylbenzene polymer (SiO2-P). In many partitioning methods using extraction chromatography, MA(III) separation from the raffinate is achieved using a two-column unit system corresponding to MA(III) Ln(III) recovery and MA(III)/Ln(III) separation, which is similar to the solvent extraction process. In this study, the authors attempted MA(III) direct separation from simulated raffinate using a novel single-column unit system. The partitioning plant for the fast reactor cycle using the singlecolumn unit system will be a simple and compact structure compared with the two-column unit system. The column for the single-column system was packed with the adsorbent, which was impregnated with R-BTP into SiO2-P, for the separation of MA(III) from the raffinate. The behaviors of Am(III) and Cm(III) in separating from the raffinate were examined through a column experiment using a single column packed with the R-BTP/SiO2-P adsorbent.

Am/Eu Separation with a New Ligand, N,N,N′,N′-tetrakis((4-butoxypyridin-2-yl)methyl)ethylenediamine (TBPEN), a Hydrophobic Derivative of TPEN

Tatsuro MATSUMURA , Yusuke INABA , Atsunori MORI & Kenji TAKESHITA (2010) Am/Eu Separation witha New Ligand, N,N,N′,N′-tetrakis((4-butoxypyridin-2-yl)methyl)ethylenediamine (TBPEN), a Hydrophobic Derivative ofTPEN, Journal of Nuclear Science and Technology, 47:2, 123-126, DOI: 10.1080/18811248.2010.9711935

Highly Practical and Simple Ligand for Separation of Am(III) and Eu(III) from Highly Acidic Media.

A new, high-performance, highly practical, simple reagent called alkyl diamide amine (ADAAM) was examined for the separation of Am(III) and Eu(III). ADAAM has three donor atoms, one soft N-donor atom and two hard O-donor atoms, on a central frame. The combination of soft and hard donor atoms affords a tridentate that ensures remarkable extraction ability and selectivity of Am(III) and Eu(III) from highly acidic media (1.5 M HNO3) with a separation factor up to 25.

Continuous extraction and separation of Am(III) and Cm(III) using a highly practical diamide amine extractant

ABSTRACT A highly practical diamide-type extractant, which is an alkyl diamide amine with 2-ethylhexyl alkyl chains (ADAAM(EH)), was investigated for the mutual separation of Am(III) and Cm(III). ADAAM(EH) is a multidentate ligand with one soft N-donor atom and two hard O-donor atoms as part of its central frame. This tridentate arrangement of donor atoms provides selective binding to Am(III) compared to that with Cm(III) in highly acidic media (1.5 M HNO3), resulting in separation factors of up to 5.5. A continuous liquid–liquid extraction and stripping test was conducted using a multistage countercurrent mixer-settler extractor with ADAAM(EH) in n-dodecane. In this test, the separation of Am(III) and Cm(III) was achieved with very high yield.

Separation of Americium (III) and Lanthanide (III) Ions using TPEN Analogs

Abstract N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,2-ethylenediamine (TPEN) has been shown previously to exhibit a high separation factor for the separation of americium (III) and europium (III). Application of TPEN is limited due to the solubility of the material under acidic conditions (pH < 4). A variety of analogs were synthesized in this study to examine effects caused by various structural modifications in an effort to retain the selectivity of the parent compound while decreasing solubility in acidic media. Results indicate that the substitution at the ethylene linker of TPEN eliminates the ability of the compound to separate americium (III) over europium (III).

Thermal-Swing Extraction Separation of Am (III) and Eu (III) with Poly-NIPA Gel Crosslinked with TPEN Derivative

The authors propose a new extraction technique applicable to the treatment process of nuclear wastes, in which the extractability of object materials is controlled by the conformational change of a polymer network with the volume phase transition of thermosensitive gel

Distribution Behavior of Neptunium by Extraction with N,N-dialkylamides (DEHDMPA and DEHBA) in Mixer-Settler Extractors

ABSTRACT The extraction properties of N,N-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) and N,N-di(2-ethylhexyl)butanamide (DEHBA) for Np(V) and Np(VI) were studied by a batch method using various nitrate ion concentrations. The distribution ratios of Np(VI) obtained with DEHDMPA and DEHBA exceeded unity when the nitrate ion concentration was > 3 mol/dm3, while DEHDMPA and DEHBA barely extracted Np(V). A continuous counter-current experiment using mixer-settler extractors was performed to evaluate the behavior of Np in a process comprising two cycles using DEHDMPA and DEHBA as extractants. The feed was nitric acid containing U, Pu, Np, and several fission products. The results indicated that part of Np(V) changed its valence state to Np(IV) or Np(VI) after the 1st experimental cycle. The recoveries of Np in the streams of U fraction and U-Pu fraction were 63.7% and 29.1%, respectively.

Evaluation of two-phase separation in N,N-di(2-ethylhexyl)butanamide-nitric acid systems using turbidity measurements

ABSTRACT Quantitative evaluation of the two-phase separation between N,N-di(2-ethylhexyl)butanamide (DEHBA) and tri-n-butyl phosphate (TBP) diluted with n-dodecane and uranyl nitrate solution in nitric acid medium was achieved using turbidity measurements. The turbidities of DEHBA were relatively high, particularly at high DEHBA concentrations, while that of TBP rapidly decreased irrespective of nitric acid concentration. A high concentration of DEHBA, nitric acid, and uranium increased the turbidities in the organic phase, which could be ascribed to the increase in viscosity. Distribution ratios of uranium were also measured, and it was indicated that turbidity did not have a critical effect on the distribution ratio when the turbidity was below a certain value.