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  • Author or Editor: H. Suganuma x
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Abstract  

An anion-exchange method is used for determining the average anionic charge of polonium species in chloride solutions. This method is based on measurements of the distribution ratio of polonium at a constant internal chloride ion concentration of the anion-exchanger phase. In 1.0 mol·dm–1 (H, Na)CL solution in a vicinity of –log[H+]=1.0, tracer concentrations of polonium(IV) is found to exist in both chemical forms of [PoCl4(OH) 2 2– ] and [PoCl3(OH) 2 ].

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Abstract  

The stability constants (β1) of the monofluoro complex of Sm(III) have been determined in mixed solvents of methanol and water at a 0.10 mol·dm−3 ionic strength using the solvent extraction technique. The values of lnβ1 increase as the mole fraction of methanol (X s) in the mixed solvent system increases. The variation in the stability constants can be correlated with both the large effect due to the solvation of F and the small effect due to both (1) the solvation of cations in connection with the complexation of SmF2+ and (2) the electrostatic attraction of Sm3+−F. Based on the variation in the sum of (1) and (2) in H2O and the mixed solvent solutions, it was determined that the coordination number (CN) of Sm(III) varied from a mixture of CN=9 and 8 to CN=8 for about a 0.06 mole fraction of methanol (X s) in the mixed solvent. TheX s value of the inflection point of the CN for Sm(III) is slightly higher thanX s=0.03 for Eu(III) previously determined by us.

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Abstract  

The stability constants, β1, of the monochloride complex of Sm(III) have been determined in mixed system of methanol and water at 1.00 mol dm−3 ionic strength using a solvent extraction technique. The values of β1 increase with an increase in the mole fraction of methanol (X s) in the mixed solvent system when 0≤X s ≤0.351. The interionic distance of Sm3+−Cl (d Sm−Cl) in the mixed solvent system was estimated by applying the Gibb's free energy derived from β1 to a Born-type equation. It was determined that an inflection point of the variation in the estimatedd Sm−Cl againstX s was present in the vicinity ofX s=0.054. The inflection point ofd Sm−Cl shows a value ofX s between those ofd Eu−Cl andd Nd−Cl previously obtained by us.

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Abstract  

The stability constants, β1, of monochloride complex of Am(III) have been determined in a mixed system of dimethyl sulfoxide (DMSO) and water at 1.00 mol·dm−3 ionic strength using solvent extraction. The values of β1 in mixed DMSO+H2O solutions decrease rapidly with an increase in the mole fraction of DMSO (X s) in mixed solvents and become negative ones, which is not in a definition of stability constant, inX s>0.04. The variation of β1 inX s≦0.02 was accounted for by the size-variation of the primary solvation sphere around Am(III), which was present as a solventshared ion-pair, and by a little effect due to an invasion (coordination) of ClO4 into the secondary solvation sphere of Am3+. On the other hand, it was concluded that the β1 obtained by solvent extraction inX s>0.02 was an apparent value, because of a large effect due to an invasion (coordination) of ClO4 into the secondary solvation sphere of Am(III).

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Abstract  

Ascending paper chromatography using Toyo No. 50 paper and n-BuOH saturated with 1.0M HNO3 as a developing solvent, was useful to examine the separation of polonium species in (H,NH4)NO3 solutions. A neutral mononuclear species (Po(OH)4) appeared in the vicinity of Rf=0.6. The Rf values of each species decreased depending on the increasing cationic tendency and polymerization of the polonium species.

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Abstract  

Radiochemical and spectrophotometric studies on the solvent extraction of tetrachloronitridotechnetate(VI) ion with tetraphenylarsonium chloride into chloroform have been reported. Analysis of the dependence of the distribution ratio for technetium species on the concentration of hydrogen ion (0.1–1.0M) revealed that an equilibrium between tetrachloronitridotechnetate(VI) ion and [(H2OCl3NTc–O–TcNCl3(H2O)]2– is established in the aqueous phase. However, formation of di(-O) dimer was suggested, when the concentration of hydrochloric acid is less than 0.2M. The extraction constant for technetium and formation constant for -oxo technetium nitrido complex were evaluated.

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Abstract  

Displacement-extraction of tracer concentrations of210Po in 1.0M (H, Na)NO3 solutions has been studied by using copper dithizonate–CCl4 solutions. Furthermore, based on the results of the displacement-extraction of polonium, a mixture of210Po,210Bi, and210Pb of tracer concentrations in 1.0M (H, Na)NO3 solutions could be satisfactorily separated with successive extractions by copper dithizonate–CCl4 and dithizone–CCl4 solutions in acidic conditions.

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Abstract  

A cation-exchange method was used for determining the stability constants of complexes formed between Bi/III/, present in tracer concentrations /ca. 10–11M Bi/, and nitrate ion or chloride ion in 1.OM H/ClO4, NO3/ or 1.OM H/Cl, ClO4/ solutions, respectively. The successive formation constants were calculated using the distribution data. The resulting 1g 1, 1g 2, and 1g 3 values were 0.74, 1.22, and 1.54 for 1.OM H/ClO4, NO3/ solutions, and 2.36, 3.61, and 4.95 for 1.OM H/Cl, ClO4/ solutions, respectively.

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Abstract  

The stability constants ( 1(F)) of the monofluoro complex of Lu(III) and those ( 1(Cl)) of the monochloride solvent-shared ion-pair of Lu(III) have been determined in mixed solvents of methanol and water at 0.10 and 1.00 mol·dm–3 ionic strengths, respectively. The variation in ln 1(F) with an increase in the mole fraction of methanol (X s) in the mixed solvent system showed an acute-angled convex inflection point at X s 0.12, an acute-angled concave inflection point at X s 0.22, and another acute-angled convex inflection point at X s 0.27. It was concluded that the first and the second convex inflection points denoted the CN of Lu3+ from CN = 8 to a mixture of CN = 8 and 7 and from CN = 8 and 7 to a mixture containing CN = 6, respectively. The concave point is the starting point of a change in the CN of Lu(III) in LuF2+ from CN = 8 to a mixture of CN = 8 and 7. The values of two inflection points of the CN around Lu3+ are consistent with the inflection points of the variation in the values of ln 1(Cl) versus the dielectric constant of the mixed solvent.

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