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- Author or Editor: H. Nakamura x
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Abstract
Radiation effects on the extraction of americium(III) with several dialkylphosphoric and monoalkylphosphoric acids have been studied comparatively. The extractants were exposed to60Co γ-rays in the absence and presence of diluent and HNO3. The Df of Am(III) was measured and the yield of radiolytic products was determined after γ-irradiation as a function of the absorbed dose. Di(hexoxyethyl)phosphoric acid was the most susceptible to radiation among the extractants studied and its extractability was weakened by radiation regardless of the presence or absence of diluent or HNO3. Diisodecylphosphoric acid itself showed an enhancement upon irradiation but incurred a depressant effect upon intimate contact with HNO3·Mono(2-ethylhexyl)phosphoric acid showed a decrease of the Df of Am(III), similarly to DIDPA in the presence of HNO3 during γ-irradiation. All the above extractants gave H3PO4 as the principal radiolytic product upon γ-irradiation upon intimate contact with HNO3 causing decreasing solely the extraction of Am(III). Di(2-ethylhexyl)phosphoric acid proved to be the most stable extractant to radiation among those studied.
Abstract
A highly precise and accurate method for the determination of minor amounts of iron by substoichiometric isotope dilution analysis is described. The constant amount of Fe(III) is substoichiometrically extracted with 2·10−4M oxine in chloroform from the aqueous phase of pH 9.2–10.0 containing 6·10−3M tartrate. The interfering ions such as Mn(II), Co(II), Ni(II), Cu(II), and Zn(II), can be removed by the preliminary extraction of Fe(III) from 7.5M hydrochloric acid solutions into isopropyl ether. The present method has been applied to the determination of iron in biological standard reference materials, i.e., the NBS Spinach (SRM-1570) and the NIES Pepperbush (SRM No. 1), and the results obtained are 548±9 ppm (NBS certified value: 550±20 ppm) and 193±4 ppm, respectively.
Abstract
Macro-porous cation exchange resin Diaion CPK-08 and gel type cation exchange resin Dowex 50WX8 were irradiated with γ-rays from60Co, while soaked in distilled water, 0.5M HNO3 or 4M HNO3, and the ion-exchange properties, such as strong- and weak-acid capacities, moisture content and wet resin volume, were examined in relation to absorbed dose. There was no appreciable difference between the radiation stabilities of the two cation exchangers. Increase of HNO3 concentration reduced the loss of strong-acid capacity and increased the decross-linkage and the weak-acid capacity. Elution characteristics of137Cs and90Sr from columns packed with γ-irradiated resin were examined and the column distribution ratio of these radionuclides and the theoretical plate number were calculated. These values decreased with the increase of absorbed dose. Diaion CPK-08 was packed into a pressurized column and irradiated with γ-rays at a dose rate of 2·106 R/hr, while water was passed through the column at a constant flow rate. The greatest change of the resin properties was observed at an upper stream position from the position of the highest radiation dose of 2·106 R/hr.
Abstract
Radiocarbon ages of 17 ancient Japanese documents of known age and 3 unknown samples were measured by AMS. Radiocarbon dating on the known documents concluded that the Japanese paper is a suitable sample for radiocarbon dating because of small discrepancy between the calibrated radiocarbon age and the historical age due to the characteristics of Japanese paper. From the dating of the paper samples of unknown age, the wood-block prints, it was clarified that they had been produced between the 11th century and the first half of the 12th century as the historical information suggested.
Abstract
Cesium content in eleven positions of a continental basalt with a columnar joint was determined by means of neutron activation analysis. Concentration of cesium is about four times higher at the altered portions of the fracture than at the unaltered. Water and Fe3+ content determined by gravimetry, Mössbauer spectroscopy, and inductively coupled plasma optical emission spectroscopy were also correlated with cesium concentration, suggesting accumulation of cesium with ferric components. Such processes may be important for estimating the behavior of radiocesium in the environment.
Abstract
The stability constans,
1, of each monochloride complex of Eu(III) have been determined in the methanol and water mixed system with 1.0 mol·dm–3 ionic strength using a solvent extraction technique. The values of
1 increase with an increase in the mole fraction of methanol (X
S
) in the mixed solvent system when 0
X
S
0.40. The, distance of Eu3+–Cl– in the mixed solvent system was calculated using the Born-type equation and the Gibbs' free energy derived from
1. Calculation of the Eu3+–Cl– distance and the preferential solvation, of Eu3+ by water proposed the variation of the outersphere complex of EuCl2+ as follows: (1) [Eu(H2O)9]3+Cl–, [Eu(H2O)8]3+Cl– and [Eu(H2O)7(CH3OH)3+Cl– inX
S
0.014, (2) [Eu(H2O)8]3–Cl– and [Eu(H2O)7(CH3OH)]3+Cl– in 0.014<X
S
<0.25 and (3) [Eu(H2O)7(CH3OH)]3–Cl– and [Eu(H2O)6(CH3OH)[2
3+Cl– in 0.25<X
S
0.40.
Abstract
The stability constants, β1, of each monochloride complex of Am(III) have been determined in a mixed system of methanol and water at 1.0 mol·dm−3 ionic strength using a solvent extraction technique. The values of β1 of Am(III) decrease up to about 0.1 mole fraction of methanol (X s) in the bulk solutions and then increase with increasingX s when 0.1<X s≤0.4. The distance of Am3+−Cl− in the mixed system was estimated using a Born-type equation. From the estimated distance of Am3+−Cl− (d Am−Cl), it is concluded that AmCl2+ in the aqueous solution is present as a solvent-shared ion-pair. Further, based on the variation of dAm−Cl with increasingX s, the variations of β1 in the system are accounted for by the size-variation of the primary solvation sphere around Am(III) and by an effect due to the presence of a slight covalency in the solvation of Am(III).
Abstract
The stability constants, β1, of each monochloride complex of Ln(III) (Ln=Nd or Tm) have been determined in the mixed system of dimethyl sulfoxide (DMSO) and water with 1.0 mol·dm−3 ionic strength using a solvent extraction technique. The values of β1 of Ln(III) decrease to about 0.2 mole fraction of DMSO (X s) in the mixed solvent system and then increase withX s (>about 0.2). However, the variation mode of β1 of Nd(III) withX s somewhat differs from that of Tm(III). Calculation of Ln3+−Cl− distance using a Born-type equation of the Gibbs' free energy derived from the β1 evealed the followings: (1) For Tm3+ with coordination number 8, the estimated distance between Tm3+ and Cl− (d Tm-Cl) increases linearly withX s in 0.00≤X s≤0.17. This means an enlargement of the primary solvation sphere size of Tm3+ withX s. On the other hand, thed Tm-Cl shows a decrease withX s in 0.17<X s<0.28. (2) The estimatedd Nd-Cl increases linearly withX s in 0.00≤X s<0.06 and 0.06<X s≤0.17, but their slopes are different. The larger slope againstX s in 0.06<X s≤0.17 is attributable to a lowering of the β1 by a coordination of ClO4 − into the secondary solvation sphere of Nd3+ and/or by an increase in the solvation number of the primary solvation sphere of Nd3+.
