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  • Author or Editor: S. Nakamura x
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Abstract  

The synergic extraction of La(III), Nd(III), Sm(III), Tb(III) and Lu(III) with 0.1M acetylacetone (Hacac) and 1,10-phenanthroline (phen) in benzene was studied. The adduct formation constant, s, for RE(acac)3 (phen) in benzene was determined. The s decreases with inceasing atomic number of RE(III). The s in different organic solvents can be predicted in connection with the activity coefficients of the solutes, and the validity of this prediction is confirmed by good agreement with the experimental values of s in carbon tetrachloride and heptane.

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Abstract  

Effects of radiation on the extraction system composed of DEHPA extractant and DTPA aqueous solution containing nitrate were studied by measuring distribution ratios of Am(III) and Nd(III) with the extractant and DTPA solution either one of which was irradiated with60Co γ-rays or the organic—aqueous mixed phase irradiated under continuous stirring. The irradiation causes an increase of Df and a decrease of the Nd/Am separation factor β, to an especially large extent in the mixed phase system. These effects are due firstly to the radiolytic decomposition of DTPA and secondarily to the formation of MEHPA. The replacement of nitrate with lactate stops the degradation of DTPA and DEHPA resulting in the retardation of increase of Df and a decrease of separation factor. The DEHPA-DTPA-lactic acid system is concluded to sustain absorption of radiation at an absorbed dose up to 200 Wh·I−1 in the partitioning of transplutonium elements in HLW.

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Abstract  

The distribution ratio of neodymium(III) in extraction with mono(2-ethylhexyl)-phosphoric acid was determined as a function of extractant and Nd(III) concentrations, and effect of co-existing DEHPA was studied. A characteristic extraction of a tracer quantity of Nd(III) was found at an extractant concentration of approximately 0.01 M. Di(2-ethylhexyl)phosphoric acid depresses the extraction of Nd(III) in MEHPA of a concentration of 0.01M, but enhances it at higher concentrations of MEHPA. Owing to the high Df values against lanthanides(III) and an excellent radiation stability, the synergistic combination of MEHPA-DEHPA, preferably at a DEHPA/MEHPA mole ratio of 3, was concluded to be applicable to the isolation of lanthanides (and actinides) from highly acidic solutions.

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Abstract  

The generation of HF with traces of TF and then conversion to HT were investigated using a bed packed with NiF2 and Zn or Fe particles. When the temperature of fine particles of Zn or Fe was elevated up to 400 °C or 550 °C, respectively, TF was completely reduced to HT. Since ZnF2 and FeF2 had no TF (and HF) adsorption capacity, memory effect was found to be negligibly small. Thus Zn and Fe particles can be used as an effective reduction material corresponding to different temperature conditions to convert TF to HT for tritium detection by ion chambers without any corrosion.

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Abstract  

The effect of network structure on the glass transition temperature (T g) was examined by differential scanning calorimetry, thermomechanical analysis and dynamic thermomechanometry for epoxy resins cured with mixtures of curing agents consisting of an active ester, 1,3,5-triacetoxybenzene (TAB), and a polyfunctional phenol, 1,3,5-trihydroxybenzene (THB). Free hydroxyl groups are formed from THB after curing, whereas acetyl groups are left from TAB. TheT g value of cured epoxy resins decreased with increasing TAB content in the curing agent, which is attributed to the looser network structure induced by the steric hindrance of acetyl groups from TAB in the curing reaction and also to the weaker intermolecular interaction and the internal plasticization of acetyl groups from TAB.

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Abstract  

The extraction behavior of Eu(III) has been studied using di(2,4,4-trimethylpentyl)phosphinic acid (DTMPPA, HA) in kerosene. Europium was extracted as Eu(HA2)3 with the extraction constant of 2.0·10–3. This extraction system was applied to the transport of Eu(III) across a DTMPPA liquid membrane supported on porous polytetrafluoroethylene. Europium was quantitatively moved through the liquid membrane containing 0.1M (HA)2 as a mobile carrier from the feed solution of pH above 3 into the product solution of 0.1M HNO3, yielding a concentration factor of ten. The transport rate increased with increasing pH and DTMPPA concentration.

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Abstract  

Synergistic effect of neutral bidentate ligands, L, such as 1,10-phenanthroline(phen), 2,9-dimethyl-1,10-phenanthroline(dmp), and 2,2-bipyridine(bpy), and of neutral unidentate ligands TBP and TOPO have been studied in the extraction of Mn(II) labeled with54Mn, using 2-thenoyl-trifluoroacetone(HTTA) in various organic solvents. The following factors play an important role in the synergistic extraction involving bidentate ligands; two-phase partition of bidentate ligands, their protonation and complex formation with Mn(II) in the aqueous phase. The mixed ligand complex, Mn(TTA)2L, is formed in all bidentate ligand systems. The adduct formation constant ( S,1) decreases in the following order; phen (lg S,1=12.64) > dmp(11.32)> · bpy(8.54) in the cyclohexane system. This order is ascribed to the bacisity and the steric effect of the bidentate ligands. Organic solvents influence both the adduct formation and the partition of the ligands, and S,1 decreases in the order cyclohexane>carbon tetrachloride>chlorobenzen = benzene>chloroform.

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Abstract  

In order to clarify the influence of radiation degradation of DEHPA upon the extraction of lanthanides, the extraction of neodymium(III) was studied using DEHPA, MEHPA, 2-ethylhexanol and γ-ray irradiated DEHPA. The most significant effect of DEHPA radiolysis on the extraction was found to be the enhacement of extraction capability mainly due to the primary radiolysis product MEHPA. 2-Ethylhexanol, another radiolysis product, showed a depressant effect on DEHPA-Nd(III) extraction. However, the mixture of MEHPA and 2-ethylhexanol improved the extraction. The mixed solvent DEHPA-MEHPA was found to be more effective than the individual components for lanthanide extraction.

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Abstract  

The substoichiometric isotope dilution analysis for manganese(II) in a synergistic extraction system of a chelating agent and a neutral ligand is described. The substoichiometric extarction is based on a substoichiometric amount of 2-thenoyltrifluoroacetone and an excess of 1,10-phenanthroline. The recommended condition and the reproducibility of the present system were examined. The present method was applied for NBS-SRM tomato leaves and NIES-SRM chlorella, and very good results with high accuracy and precision were demonstrated.

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Abstract  

The substoichiometric separation of Yb(III) can be achieved by the extraction of a substoichiometric amount of thenoyltrifluoroacetone and an excess amount of phenanthroline in benzene. The appropriate pH range for the substoichiometric extraction is 6–8. The reproducibility of the substoichiometric extraction of Yb(III) is very good as RSD 1%. As an example, Yb in a manganese nodule is determined by the substoichiometry combined with the radioactivation analysis. The content of Yb is 17.63±0.23 g/g. The present procedure can be applied to the determination of other rare earth elements.

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