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Journal Articles

Re-evaluation of radiation-energy transfer to an extraction solvent in a minor-actinide-separation process based on consideration of radiation permeability

Toigawa, Tomohiro; Tsubata, Yasuhiro; Kai, Takeshi; Furuta, Takuya; Kumagai, Yuta; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 39(1), p.74 - 89, 2021/00

Absorbed-dose estimation is essential for evaluation of the radiation feasibility of minor-actinide-separation processes. We propose a dose-evaluation method based on radiation permeability, with comparisons of heterogeneous structures seen in the solvent-extraction process, such as emulsions forming in the mixture of the organic and aqueous phases. A demonstration of radiation-energy-transfer simulation is performed with a focus on the minor-actinide-recovery process from high-level liquid waste with the aid of the Monte Carlo radiation-transport code PHITS. The simulation results indicate that the dose absorbed by the extraction solvent from alpha ray depends upon the emulsion structure, and that from beta and gamma ray depends upon the mixer-settler-apparatus size. Non-negligible contributions of well-permeable gamma rays were indicated in terms of the plant operation of the minor-actinide-separation process.

Journal Articles

Minor actinides separation by ${it N,N,N',N',N'',N''}$-hexaoctyl nitrilotriacetamide (HONTA) using mixer-settler extractors in a hot cell

Ban, Yasutoshi; Suzuki, Hideya*; Hotoku, Shinobu; Tsutsui, Nao; Tsubata, Yasuhiro; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 37(7), p.489 - 499, 2019/11

 Times Cited Count:0 Percentile:100(Chemistry, Multidisciplinary)

A continuous counter-current experiment to separate minor actinides (MAs: Am and Cm) was performed with ${it N,N,N',N',N'',N''}$-hexaochyl nitrilotriacetamide (HONTA) as an extractant. Nitric acid of 0.08 M (mol/dm$$^{3}$$) containing MAs and rare earths (REs) recovered from high-level waste was used as the Feed, and the experiment was conducted for 14 h. The ratios of Am and Cm recovered into the MA fraction measured 94.9% and 78.9%, respectively. HONTA hardly extracted Y, La, and Eu in the Feed (99.9% for Y, 99.9% for La, and 96.7% for Eu), most of which were distributed to the RE fraction. A portion of Nd was extracted by HONTA, and consequently the ratio of Nd in the RE fraction was 83.5%. The concentrations of MAs and some REs in each stage were calculated using a simulation code, and the results are consistent with the experimental values. This code indicates that the ratios of MAs in the MA fraction and REs in the RE fraction could be $$geq$$99% by optimizing separation conditions.

Journal Articles

Extraction performance of a fluorous phosphate for Zr(IV) from HNO$$_{3}$$ solution; Comparison with tri-$$n$$-butyl phosphate

Ueda, Yuki; Kikuchi, Kei; Sugita, Tsuyoshi; Motokawa, Ryuhei

Solvent Extraction and Ion Exchange, 37(5), p.347 - 359, 2019/07

 Times Cited Count:1 Percentile:78.85(Chemistry, Multidisciplinary)

We have newly-designed fluorous phosphate(TFP) for the effective Zr(IV) ion extractant as an alternative extractant against the conventional organic phosphate, tri-$$n$$-butyl phosphate(TBP). Zr(IV) ion extraction system using the TBP has many problems such as the formation of the third phase during liquid-liquid extraction. Here, we develop the fluorous extraction system based on the TFP-perfluorohexane for the Zr(IV) ion extraction to improve the Zr(IV) ion extraction system with an effective extractability and without the third phase formation. Our main findings were that the significant high extraction performance of the TFP for Zr(IV) ion as compared with TBP, and the origins of the high extraction performance of the TFP are related to the water and HNO$$_{3}$$ contents in the fluorous phase and the stability of the complex, Zr(No$$_{3}$$)$$_{4}$$(TFP)$$_{3}$$.

Journal Articles

Extraction of trivalent rare earths and minor actinides from nitric acid with ${it N,N,N',N'}$-tetradodecyldiglycolamide (TDdDGA) by using mixer-settler extractors in a hot cell

Ban, Yasutoshi; Suzuki, Hideya; Hotoku, Shinobu; Kawasaki, Tomohiro*; Sagawa, Hiroshi*; Tsutsui, Nao; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 37(1), p.27 - 37, 2019/00

 Times Cited Count:7 Percentile:25.96(Chemistry, Multidisciplinary)

A continuous counter-current experiment using TDdDGA was performed using mixer-settler extractors installed in a hot cell. Nitric acid containing minor actinides (MAs: Am and Cm), rare earths (REs: Y, La, Nd, and Eu), and other fission products (Sr, Cs, Zr, Mo, Ru, Rh, and Pd) was fed to the extractor. TDdDGA effectively extracted MAs and REs from the feed, while other fission products were barely extracted. The extracted MAs and REs were back-extracted by bringing them in contact with 0.02 mol/dm$$^{3}$$ nitric acid, and they were collected as the MA-RE fraction. The proportions of MA and RE in the MA-RE fraction were $$>$$ 98% and $$>$$ 86%, respectively. These results demonstrated the applicability of TDdDGA as an extractant for MAs and REs.

Journal Articles

Quantitative analysis of Cs extraction by some dialkoxycalix[4]arene-crown-6 extractants

Simonnet, M.; Miyazaki, Yuji*; Suzuki, Shinichi; Yaita, Tsuyoshi

Solvent Extraction and Ion Exchange, 37(1), p.81 - 95, 2019/00

 Times Cited Count:1 Percentile:78.85(Chemistry, Multidisciplinary)

Journal Articles

Solvent extraction of uranium with ${it N}$,${it N}$-di(2-ethylhexyl)octanamide from nitric acid medium

Tsutsui, Nao; Ban, Yasutoshi; Sagawa, Hiroshi; Ishii, Sho; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 35(6), p.439 - 449, 2017/08

 Times Cited Count:3 Percentile:77.12(Chemistry, Multidisciplinary)

Solvent extraction of uranium from a nitric acid medium was performed with ${it N}$,${it N}$-di(2-ethylhexyl)octanamide (DEHOA) by a single-stage batch method, and the distribution ratio equation of U(VI) was derived as $${it D}_{rm U}$$ = 1.1$$[rm NO^{-}_{3}]^{1.6}_{rm aq}[{rm DEHOA}]^{2}_{rm org}$$. Furthermore, the nitric acid distribution was also evaluated, and the distribution ratio equation $${it D}_{rm H}$$ = 0.12$$[rm H^{+}]^{0.76}_{rm aq}[{rm DEHOA_{rm Free}}]_{rm H}$$ was obtained. Batch experiments to evaluate the time dependence of U(VI) extraction and the U(VI) loading capacity of DEHOA were also performed. It was revealed that U(VI) extraction by DEHOA reached an equilibrium state within a few minutes, and the loading capacity was 0.71 mol/dm$$^{3}$$ (M) when the concentrations of DEHOA and nitric acid were 1.5 and 3.0 M, respectively.

Journal Articles

Neutron polarization analysis for biphasic solvent extraction systems

Motokawa, Ryuhei; Endo, Hitoshi*; Nagao, Michihiro*; Heller, W. T.*

Solvent Extraction and Ion Exchange, 34(5), p.399 - 406, 2016/07

 Times Cited Count:3 Percentile:86.63(Chemistry, Multidisciplinary)

Journal Articles

Distribution behavior of neptunium by extraction with ${it N,N}$-dialkylamides (DEHDMPA and DEHBA) in mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsutsui, Nao; Tsubata, Yasuhiro; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 34(1), p.37 - 47, 2016/01

 Times Cited Count:5 Percentile:69.82(Chemistry, Multidisciplinary)

The extraction properties of ${it N,N}$-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) and ${it N,N}$-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/L. DEHDMPA and DEHBA barely extracted Np(V), and the maximum distribution ratios were 0.4 and 0.2 when DEHDMPA and DEHBA were used as extractants, respectively. A continuous counter-current experiment was performed to evaluate the behavior of Np in a process comprising two cycles. The ratio of Np recovered to the U fraction and U-Pu fraction were 63.7% and 29.1%, respectively. The behavior of Np suggested that the valence state of Np changed from Np(V) to Np(IV) or Np(VI) after the 1st experimental cycle. The recoveries of U and Pu to the U fraction stream and the U-Pu fraction stream were 99.9% and 99.8%, respectively.

Journal Articles

The Effect of alkyl substituents on actinide and lanthanide extraction by diglycolamide compounds

Sasaki, Yuji; Sugo, Yumi; Morita, Keisuke; Nash, K.*; Nash, K. L.*

Solvent Extraction and Ion Exchange, 33(7), p.625 - 641, 2015/10

 Times Cited Count:47 Percentile:13.41(Chemistry, Multidisciplinary)

The effect of alkyl substituents at amidic N atoms in diglycolamide (DGA) compounds on solvent extraction was investigated. The solubility in water and n-dodecane, loading capacity, and distribution ratio (D) of lanthanides and actinides for various DGA compounds were monitored. DGA derivatives with short alkyl chains, for example methyl and ethyl groups, are highly water soluble, while DGA derivatives with long alkyl chains are highly soluble in n-dodecane. The loading capacity correlats with their alkyl chain lengths. The results of masking effect and solubility tests indicate that TEDGA(tetraethyl-diglycolamide) is the best actinide masking agent among the water-soluble DGA derivatives. Actinide extractions were performed using ten DGA compounds in six diluents (nitrobenzene, 1,2-dichloroethane, 1-octanol, chloroform, toluene, and n-dodecane), in which it was observed that DGA derivatives with shorter alkyl chains show higher D values.

Journal Articles

Uranium and plutonium extraction from nitric acid by ${it N,N}$-di(2-ethylhexyl)-2,2-dimetnylpropanamide (DEHDMPA) and ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA) using mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsubata, Yasuhiro; Morita, Yasuji

Solvent Extraction and Ion Exchange, 32(4), p.348 - 364, 2014/05

 Times Cited Count:6 Percentile:74.63(Chemistry, Multidisciplinary)

Extraction properties of ${it N,N}$-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) for nitric acid, U(VI), and Pu(IV) were studied, and the distribution ratio equations were derived for each chemical species. A continuous counter-current experiment was performed using mixer-settler extractors with two types of monoamides, DEHDMPA and ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA), as extractants. DEHDMPA exclusively extracted U from the feed, and the ratio of U recovered in the U fraction stream was 99.93%. Almost all Pu were extracted by DEHBA, and the recovery of Pu in the U-Pu fraction stream was 99.94%. Concentrations of U and Pu in mixer-settlers were calculated using a simulation code, which confirmed that the calculation was effective for estimating the U concentration in the U fraction stream, and the U and Pu concentrations in the U-Pu fraction stream.

Journal Articles

Studies on the uptake and column chromatographyic separation of Eu, Th, U, and Am by tetramethylmalonamide resin

Shimada, Asako; Sulakova, J.*; Yang, Y.*; Alexandratos, S.*; Nash, K. L.*

Solvent Extraction and Ion Exchange, 32(1), p.27 - 43, 2014/01

 Times Cited Count:1 Percentile:93.19(Chemistry, Multidisciplinary)

A tetramethylmalonamide-functionalized resin (TMMA resin) has been developed and investigated for its ability to separate trivalent, tetravalent, and hexavalent actinide elements. As a fundamental study of the extraction mechanism and to design a chromatographic separation scheme, distribution coefficients ($$K$$$$_{d}$$) for partitioning of Eu(III), Th(IV), U(VI), and Am(III) onto the resin from HNO$$_{3}$$, NaNO$$_{3}$$, HCl and NaCl solutions with and without organic acids and potential consistents of low-level radioactve waste have been determined. The competition between metal extraction and HNO$$_{3}$$ extraction was confirmed by the extraction data and FT-IR spectra. Based on these fundamental experimental results, an extractive chromatographic scheme for actinide isolation was designed and demonstrated.

Journal Articles

Recovery of U and Pu from nitric acid using ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA) in mixer-settler extractors

Ban, Yasutoshi; Hotoku, Shinobu; Tsubata, Yasuhiro; Morita, Yasuji

Solvent Extraction and Ion Exchange, 31(6), p.590 - 603, 2013/09

 Times Cited Count:8 Percentile:61.25(Chemistry, Multidisciplinary)

The recovery of U and Pu from nitric acid using the monoamide extractant ${it N,N}$-di(2-ethylhexyl)butanamide (DEHBA) in mixer-settler extractors was calculated using a simulation code, and a continuous counter-current experiment using mixer-settler extractors was performed. The flow rate, stage number, and nitric acid concentration were chosen as the parameters for the calculation, and the appropriate experimental conditions for separating U from Pu were determined. The results of the continuous counter-current experiment showed that the percentages of U and Pu extracted using 1.5 mol/dm$$^{3}$$ (M) DEHBA from 4 M nitric acid were $$>$$99.9% and 97.84%, respectively.

Journal Articles

Crosslinked-chelating porous sheet with high dynamic binding capacity of metal ions

Wada, Go*; Ishihara, Ryo*; Miyoshi, Kazuyoshi*; Umeno, Daisuke*; Saito, Kyoichi*; Asai, Shiho; Yamada, Shinsuke*; Hirota, Hideyuki*

Solvent Extraction and Ion Exchange, 31(2), p.210 - 220, 2013/02

 Times Cited Count:2 Percentile:84.96(Chemistry, Multidisciplinary)

A crosslinked chelating porous sheet was prepared by cografting ethylene glycol dimethacrylate (EGDMA) with glycidyl methacrylate onto an electron-beam-irradiated porous polyethylene sheet, followed by the introduction of an iminodiacetate group. At a molar percentage of EGDMA of 1.0 mol%, the sheet exhibited a maximum dynamic binding capacity for copper ions of 0.93 mmol/g, while the equilibrium binding capacity remained the same (1.2 mmol/g) as that of a non-crosslinked chelating porous sheet. The crosslinking of the grafted chain causes copper ions to lower their diffusion rate along the sheet thickness driven by the gradient of the amount of copper ions adsorbed.

Journal Articles

Distribution of U(VI) and Pu(IV) by ${it N,N}$-di(2-ethylhexyl)butanamide in continuous counter-current extraction with mixer-settler extractor

Ban, Yasutoshi; Hotoku, Shinobu; Morita, Yasuji

Solvent Extraction and Ion Exchange, 30(2), p.142 - 155, 2012/02

 Times Cited Count:7 Percentile:66.72(Chemistry, Multidisciplinary)

The extraction properties of 1.5 mol/dm$$^{3}$$ (M) ${it N,N}$-di-(2-ethyl-hexyl)butanamide (DEHBA) diluted with ${it n}$-dodecane toward U(VI) and Pu(IV) were studied using a single stage batch method, and the distribution ratios toward U(VI) and Pu(IV) were, respectively, obtained as follows: ${it D}$ $$_{rm U}$$ = 1.4[NO$$_{3}$$ $$^{-}$$]$$^{1.6}$$[DEHBA$$_{rm free}$$]$$^2$$ and ${it D}$ $$_{rm Pu}$$ = 0.11[NO$$_{3}$$ $$^{-}$$]$$^{3.3}$$[DEHBA$$_{rm free}$$]$$^2$$. A continuous counter-current experiment with 1.5 M DEHBA as an extractant was performed using mixer-settler extractors. The ratios of U(VI) and Pu(IV) extracted by 1.5 M DEHBA in the U-Pu extraction step were more than 99.9%. The extracted Pu(IV) was back-extracted using 0.67 M nitric acid, and more than 97% of Pu(IV) in the feed was recovered in the Pu fraction. The present results indicated that DEHBA works as an extractant for mutual separation of U(VI) and Pu(IV) by adjusting the nitric acid concentration without using Pu(IV) reductants.

Journal Articles

Dependence of lanthanide-ion binding performance on HDEHP concentration in HDEHP impregnation to porous sheet

Ishihara, Ryo*; Asai, Shiho; Otosaka, Shigeyoshi; Yamada, Shinsuke*; Hirota, Hideyuki*; Miyoshi, Kazuyoshi*; Umeno, Daisuke*; Saito, Kyoichi*

Solvent Extraction and Ion Exchange, 30(2), p.171 - 180, 2012/02

 Times Cited Count:6 Percentile:69.88(Chemistry, Multidisciplinary)

Journal Articles

Selective extraction of U(VI) by counter-current liquid-liquid extraction with $$N$$,$$N$$-di(2-ethylhexyl)-2,2-dimethylpropanamide

Ban, Yasutoshi; Hotoku, Shinobu; Morita, Yasuji

Solvent Extraction and Ion Exchange, 29(4), p.519 - 533, 2011/07

 Times Cited Count:12 Percentile:56.06(Chemistry, Multidisciplinary)

A continuous counter-current extraction experiment for selective extraction of U(VI) using $$N$$,$$N$$-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) as an extractant was carried out with mixer-settler type extractors consisting of a U extraction step, a scrub step, and a U back-extraction step. DEHDMPA selectively extracted U(VI) over Pu(IV), and the decontamination factor against Pu(IV) in the U fraction was 990. Fractional distributions of U(VI) in the U fraction and Pu(IV) in the raffinate were 94.5% and 99.9%, respectively. Numerical simulation for calculating U(VI) and Pu(IV) concentrations in each stage of the mixer-settlers was performed. The calculated values agreed with experimentally measured U(VI) and Pu(IV) concentrations in the U extraction step, and also agreed with experimentally measured U(VI) concentrations in the scrub step.

Journal Articles

Thermodynamic and spectroscopic studies on Am(III) and Eu(III) in the extraction system of ${it N,N,N',N'}$-tetraoctyl-3-oxapentane-1,5-diamide in $$n$$-dodecane/nitric acid

Arisaka, Makoto; Kimura, Takaumi

Solvent Extraction and Ion Exchange, 29(1), p.72 - 85, 2011/02

 Times Cited Count:34 Percentile:29.25(Chemistry, Multidisciplinary)

Thermodynamic parameters (${it $Delta$G}$, ${it $Delta$H}$ and ${it $Delta$S}$) for the extraction of trivalent f-elements, M(III) (M = Am, Eu), with ${it N,N,N',N'}$-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) were determined in nitric acid/$$n$$-dodecane extraction system. The extraction of M(III) with TODGA was more exothermic than those with octyl(phenyl)-${it N}$,${it N}$-diisobutylcarbamoylmethyl phosphine oxide (CMPO) and dihexyl-${it N}$,${it N}$-diethylcarbamoylmethyl phosphonate (DHDECMP). The difference in ${it $Delta$H}$ between the extractants was attributed to the difference in the binding mode between them, i.e. tridentate (TODGA) and bidentate (CMPO and DHDECMP). In addition, from the results of luminescence lifetime measurement, it was found that the inner-sphere of extracted Eu(III) was dehydrated completely, and occupied by TODGA and/or NO$$_{3}$$$$^{-}$$.

Journal Articles

Overview of solvent extraction chemistry for reprocessing

Tachimori, Shoichi*; Morita, Yasuji

Ion Exchange and Solvent Extraction, Vol.19, p.1 - 63, 2009/08

The present paper is a review of solvent extraction chemistry for reprocessing including the separation of minor actinides, cesium and strontium, prepared for the first chapter in Ion Exchange and Solvent Extraction Vol.19 which gives status of solvent extraction study in the world. The review deals with advanced PUREX process, new extractants and new extraction system for minor actinides, Cs and Sr, and etc.

Journal Articles

Synergistic extraction of Am(III) and Eu(III) by tris(2-pyridylmethyl)amine with various anions in 1,2-dichloroethane

Ishimori, Kenichiro; Watanabe, Masayuki; Yaita, Tsuyoshi; Kimura, Takaumi; Yamada, Takashi*; Shinoda, Satoshi*; Tsukube, Hiroshi*

Solvent Extraction and Ion Exchange, 27(4), p.489 - 500, 2009/07

 Times Cited Count:3 Percentile:79.91(Chemistry, Multidisciplinary)

The remarkable enhancements of the extraction efficiency of Am(III) and Eu(III) and the separation efficiency between Am(III) and Eu(III) were achieved through changes in counter anions and/or organic solvents, in the solvent extraction of Am(III) and Eu(III) with a tripodal ligand, tris(2-pryidylmethyl)amine (tpa). The separation factor (Am/Eu), which is defined as the ratio between the distribution ratios of Am(III) and Eu(III), ranged from 10 to 50 using various combinations of counter anions and organic solvents. The extraction equilibria of Am(III) and Eu(III) with tpa in 1,2-dichloroethane were determined in detail through slope analyses in order to elucidate the mechanism of separation and identify the extracted species.

Journal Articles

2,2'-(Methylimino)bis($$N,N$$-dioctylacetamide) (MIDOA), a new tridentate extractant for technetium(VII), rhenium(VII), palladium(II), and plutonium(IV)

Sasaki, Yuji; Ozawa, Masaki; Kimura, Takaumi; Ohashi, Kozaburo*

Solvent Extraction and Ion Exchange, 27(3), p.378 - 394, 2009/05

 Times Cited Count:30 Percentile:31.73(Chemistry, Multidisciplinary)

2,2'-(Methylimino)bis($$N,N$$-dioctylacetamide) (MIDOA) was developed as a new extractant for Tc-extraction. MIDOA has a similar backbone to TODGA, $$N,N,N',N'$$-tetraoctyl-diglycolamimde, the nitrogen atom bonded with methyl group is introduced, instead of ether oxygen in TODGA. MIDOA has a high lipophilic property and is ready to use in the HNO$$_{3}$$-${it n}$-dodecane extraction system. Tc(VII), Cr(VI), Re(VII), Mo(VI), W(VI), Pd(II) and Pu(IV) are well-extracted by MIDOA. The ${it D}$(Tc) values decrease gradually with HNO$$_{3}$$, H$$^{+}$$, and NO$$_{3}$$$$^{-}$$ concentrations, and log ${it D}$ vs. log [MIDOA] relation supports the species extracted to be 1:1 metal-ligand complex. It is clear that MIDDA (2,2'-(Methylimino)bis($$N,N$$-didodecylacetamide)) and IDDA (2,2'-(Imino)bis($$N,N$$-didodecylacetamide)), which show analogous structures with MIDOA, have similar extraction behavior to that of MIDOA.

36 (Records 1-20 displayed on this page)