Search Results

You are looking at 1 - 10 of 29 items for :

  • Author or Editor: H. Watanabe x
  • Chemistry and Chemical Engineering x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

In order to reveal the reactivity of toluenethiols, the hydrogen isotope exchange reaction between one of three toluenethiols (o ,m , andp ) and poly (vinyl alcohol) labeled with tritium was observed at 50 90°C. The reaction was analyzed with both the data obtained and theA -McKay plot method, and the following has been quantitatively clarified: (1) the reactivity order of toluenethiols is (o >(m )>(p ); (2) the temperature dependences of the reactivity of toluenethiols are nearly equal; (3) the reactivity of benzenethiol is considerably decreased by the CH3 group bonded to the ortho position.

Restricted access

Abstract  

Time resolved Mössbauer spectra were measured for57Co-labelled Co/IO3/2 using a delayed coincidence technique. A life-time for unstable57Fe(II)-species formed through EC-decay was estimated to be 43±5 ns at room temperature and the initial distribution of57Fe(II)/57Fe(III) at 14.4 keV nuclear level to be 0.47±0.13. The results are discussed in terms of electron transfer from the decayed57Fe(II) atoms to iodate ions.

Restricted access

Abstract  

Reaction products of [2]ferrocenophane with CF3COOH, CCl3COOH, CF3SO3H and SbCl5 were prepared. Mössbauer spectroscopic data and magnetic susceptibility measurements suggest the bond formation of Fe–H+ and Fe–Cl+, in which iron atoms are in a high-spin Fe/II/state.

Restricted access

Abstract  

Extraction behaviors of Pd(II) in the TRUEX and PUREX solvent extractions were studied by using octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide. The effect of scrubbing in the TRUEX solvent extraction was demonstrated by adding oxalic acid. The distribution ratios of palladium (D Pd's) in the diluted region of [HNO3] were found to depend strongly on the fraction of cationic species, Pd(NO3)+, existed in the aqueous phase. The gradual decrease of DPd with the increase of acidity beyond [H+] 1 mol·dm-3 was controlled by the formation of the anionic species Pd(NO3)3 -.

Restricted access

Abstract  

Adsorption behavior of fission products in nitric acid solution on various alloys and metals was studied by using a multitracer produced by neutron irradiation of UO2. The adsorption behavior of the fission products 99Mo, 131I, 132Te, 140La, and 143Ce, and 239Np was simultaneously studied. Some chemical decontamination tests were also examined. Clear adsorption of 99Mo, 131I, and 132Te was observed, whereas adsorption of 140La, 143Ce, and 239Np was not. The adsorption characteristics were discussed by considering anion-exchange reaction and surface complexation.

Restricted access

Abstract  

KX-ray-gated emission Mössbauer spectra of57Co-labelled CoF2 and CoF2.2H2O were measured at room temperature, using the coincidence technique. A difference was found in the relative intensity of57Fe(II)/57Fe(III) between the X-ray-gated and non-gated emission spectra. The results are explained in terms of local radiolytic effects of water of crystallization and the chemical effects associated with the de-excitation processes caused by EC-decay.

Restricted access

Abstract  

A new spectrophotometric determination of technetium has been developed by means of the solvent extraction of tris(1,10-phenanthroline)iron(II) ([Fe(phen)3 2+]) with pertechnetate into nitrobenzene. The concentration of technetium can be determined by measuring the characteristic absorbance at 516 nm (=11,700M–1·cm–1) in the organic phase. An important feature of the proposed method is that the concentration of pertechnetate can be determined without complicated processes such as the reduction of pertechnetate and the subsequent formation of a colored chelate.

Restricted access

Abstract  

The stability constants (b1) of the monofluoro complex of Cm(III) have been determined in mixed solvents of methanol and water using the solvent extraction technique. The values of lnb1 increase as the molar fraction of methanol (Xs) in the mixed solvent increases. The variation in the stability constants mainly depends on the solvation of F- and slightly depends on both (1) the solvation of cations in connection with the complexation of CmF2+ and (2) the electrostatic attraction of Cm3+-F-. The variation in lnb1 for Cm(III) due to the effect of both (1) and (2) is similar to that for Sm(III). By variation of lnb1 the coordination number in the primary hydration sphere (CN) of Cm(III) decreased from a value between CN = 9 and CN = 8 to CN = 8, at about Xs = 0.02. The Xs value of the inflection point of the CN for Cm is slightly lower than Xs = 0.06 for Sm(III) and Xs = 0.03 for Eu(III), previously obtained.

Restricted access

Redox substoichiometry in isotope dilution analysis

V. The use of potassium bromate as the oxidizing agent in the analysis of metallic zinc for antimony

Journal of Radioanalytical and Nuclear Chemistry
Authors: T. Kambara, J. Suzuki, H. Yoshioka, and Y. Watanabe

Abstract  

Radiometric titration of antimony(III) with potassium bromate in hydrochloric acid media using the standard series method provided much valuable informations on the titration errors which depended on the concentrations of the acid and antimony(III). The hydrochloric acid concentrations between 2.5 and 3.0M were found to be optimum for the oxidation of antimony(III) amounts of 4 μg or less. Under these optimum reaction conditions the redox substoichiometric isotope dilution analysis was applied to the determination of antimony in metallic zinc and the satisfactory results were obtained, without the separation of matrix element. Also, the merits of various oxidizing agents hitherto studied for the quantitative oxidation of antimony(III) were compared and discussed.

Restricted access

Simulation of the atmospheric dispersion of 85Kr from a reprocessing plant over a coastal area

Performance examination of an emergency environmental radiation dose evaluation code system, SIERRA-II

Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Takeyasu, T. Iida, H. Watanabe, M. Takeishi, and A. Yamamoto

Abstract  

The performance of the computer code system, SIERRA-II, for calculating the environmental radiation dose due to an accident was assessed over a coastal area, using the environmental monitoring data around the coastally located Tokai Reprocessing Plant (TRP) when 85Kr was discharged during its operation. The agreement within a factor of 5 between the calculated and observed air concentrations of 85Kr in areas of a few km from the TRP was achieved in 57% of the comparison data, disregarding the internal boundary layer. The mean fraction bias was −0.6, which meant a slight overestimation. According to the vertical profile of the atmospheric temperatures, the internal boundary layer was modeled with the SIERRA-II and the agreement became better than when the internal boundary layer was not considered.

Restricted access