Kaoru Ueno

The precipitation of some actinide element complex ions by using hexammine cobalt(III) cation—I: The precipitation of thorium and plutonium(IV) carbonate complex ions with hexammine cobalt(III) chloride

Abstract The precipitation behavior of thorium, neptunium(V), plutonium(IV) and americium(III) in ammonium carbonate solution with hexammine cobalt(III) chloride was studied. Orange and green-yellow precipitates were produced in the case of thorium and plutonium(IV), respectively, while no precipitate of americium(III) was observed under the same conditions. On the other hand, neptunium(V) was precipitated as a white compound in ammonium carbonate solution before hexammine cobalt(III) chloride was added. The composition of the thorium and plutonium(IV) compounds were dihexammine cobalt(III) thorium pentacarbonate aquo trihydrate, [Co(NH3)6]2[Th(CO3)5·H2O]·3H2O, and dihexammine cobalt(III) plutonium(IV) pentacarbonate aquo tetrahydrate, [Co(NH3)6]2[Pu(CO3)5·H2O.]·4H2O. Chemical and crystallographic properties of the two compounds and crystallographic property of the uranium(VI) compound were also studied.

The precipitation of some actinide element complex ions by using hexammine cobalt(III) cation — II: The precipitation of thorium, uranium(VI) and plutonium(IV), (VI) sulfate complex ions with hexammine cobalt(III) cation

Abstract The precipitation behavior of thorium, uranium(VI), neptunium(V), plutonium(IV), (VI) and americium(III) in an ammonium sulfate solution with hexammine cobalt(III) ion was studied. Orange colored precipitates were produced in the case of thorium, uranium(VI) and plutonium(VI), and green yellow colored precipitate was produced in the case of plutonium(IV), respectively. On the other hand, no precipitate of neptunium(V) and americium(III) was observed under the same conditions. The compositions of the thorium, uranium(VI) and plutonium(IV) compounds were, respectively, di[hexammine cobalt(III)][thorium pentasulfate] dihydrate, [Co(NH 3 ) 6 ] 2 [Th(SO 4 ) 5 ]·2H 2 O, di{[hexammine cobalt(III)]bisulfate} [uranium(VI) dioxo trisulfate] pentahydrate, {[Co(NH 3 ) 6 ]·HSO 4 } 2 [UO 2 (SO 4 ) 3 ]·5H 2 O, and di[hexammine cobalt(III)][plutonium(IV) pentasulfate]trihydrate, [Co(NH 3 ) 6 ] 2 [Pu(SO 4 ) 5 ]3H 2 O. Chemical and crystallographic properties of the three compounds and crystallographic property of the plutonium(VI) compound were also studied.

The precipitation of some actinide element complex ions by using hexammine cobalt(III) cation—VI The precipitation of Np(IV), (V) and (VI) sulfate complex ions with hexammine cobalt(III) cation

Abstract Precipitation behaviors of Np(IV), (V) and (VI) in sulfuric acid and ammonium sulfate solutions with hexammine cobalt(III) ion have been studied. The optimum conditions of precipitating Np as crystalline compounds are 0.4 M H 2 SO 4 and 0.06 M [Co(NH 3 ) 6 ]Cl 3 for Np(IV), larger than 0.5 M (NH 4 ) 2 SO 4 and 0.03 M [Co(NH 3 ) 6 ]Cl 3 for Np(V), and the higher the concentrations the better for Np(VI). Np(IV) is completely removed from ammonium sulfate solution. Composition of the Np(IV) compound from the sulfuric acid solution is [Co(NH 3 ) 6 ] 2 [Np(SO 4 ) 5 ]· n H 2 O. And composition of the Np(V) compounds is possibly [Co(NH 3 ) 6 ][NpO 2 (SO 4 ) 2 ]·α[Co(NH 3 ) 6 ] 2 (SO 4 ) 3 · n H 2 O (α = 2.20−0.32). Solubilities of the Np(IV), (V) and (VI) compounds in water are found to be 4.9 mgNp/l, 520 mgNp/l, and 250 mgNp/l, respectively.

The precipitation of some actinide element complex ions by using hexammine cobalt(III) cation—III The precipitation of neptunium(VI) and americium(VI) sulfate complex ions with hexammine cobalt(III) cation

Abstract The crystalline compounds {[Co(NH3)6]HSO4}2[NpO2(SO4)3]. nH2O and {[Co(NH3)6] HSO4}2[AmO2(SO4)3] · nH2O were prepared by addition of hexammine cobalt(III) ion to an aqueous solution of M O22+. They are isostructural with {[Co(NH3)6]HSO4}2[UO2(SO4)3]·5H2O: c symmetry of the diamond type, with lattice constant a = 10·74 A for both neptunium and americium compounds. Absorption spectra for neptunium(VI), plutonium(VI) and americium(VI) compounds in dilute sodium carbonate solution are also presented.

The precipitation of the lanthanide elements complexes with hexammine cobalt(III) cation—I: The sulfate complexes of the trivalent lanthanide elements

Abstract Precipitation behaviors of the trivalent lanthanide elements and yttrium in potassium and ammonium carbonate solutions with addition of hexammine cobalt(III) chloride as the precipitant were examined. La to Tb in K2CO3 solution and La to Lu and Y in (NH4)2CO3 solution precipitated as scarcely soluble crystalline complexes. Lighter lanthanide elements are more easily precipitated and their solubilities are smaller than the heavier ones. Three different compositions of the precipitates are formed, as follows: [I] [Co(NH3)6][Ln(CO3)3]·nH2O, [II] [Co(NH3)6][Ln(CO3)3]·1/2[Ln2(CO3)3]·nH2O and [Co(NH3)6][Ln(CO3)3]·α[Co(NH3)6]2(CO3)3·nH2O(α=0.1–0.3)

Ion Exchange Behaviors of Inorganic Ions in Ion Exchange Resins of Diaion SKN-1 and SAN-1

The distribution ratios of 42 inorganic ions were radiochemically determined in a system of Diaion SKN-1 in H-form and 0–4M hydrochloric acid, and in another system of Diaion SAN-1 in Cl-form and 1–9M hydrochloric acid. The results are presented in an arrangement that follows the sequence of the periodic table. Several data were also obtained on Amberlite IRN-77 and −78 for comparison.

Flow Rate and Decontamination Factor of 137Cs and 131I through Mixed Resin Bed

Aqueous solutions of 131I and of 137Cs were passed through an ion exchange resin column. The resin bed consisted of a 2:1 mixture of cation and anion exchange resins, Diaion SKN-1 in H form and Diaion SAN-1 in OH form. The decontamination factors for these radioisotopes were determined at various flow rates, i.e., space velocities of 25–200. The decontamination factor decreased with increasing flow rate for both radioisotopes. The Kd value of l37Cs between Diaion SKN-1 and water was about half that of 131I between Diaion SAN-1 and water, but D.F. of 137Cs was higher. Distribution of 137Cs in the resin column was also studied. Most of radioactivity was found at the top of the resin column.

Determination of small amounts of TBP and DBP in uranyl nitrate solutions.

Tri- and dibutylphosphate (TBP and DBP) in concentrated uranyl nitrate solution are determined by a method based on the solvent extraction of zirconium-95. The distribution ratio of zirconium-95 between dilute solutions of TBP and DBP in dodecane and 10M hydrochloric acid and 1Mnitric acid respectively is measured. There is a logarithmic relationship between the distribution ratio and concentration of TBP and DBP, which enables them to be determined rapidly and with an error of +/- 10% over the range 1-100ppm of TBP and 40-600 ppm of DBP. The lower limit is 0.5 ppm for TBP and 10 ppm for DBP.

The precipitation of the lanthanide elements complexes with hexammine cobalt(III) cation—III: Precipitation behaviors and the compositions of the Ce(IV) sulfate and carbonate complexes

Abstract Precipitation behaviors of tetravalent cerium from (NH 4 ) 2 SO 4 , H 2 SO 4 and (NH 4 ) 2 CO 3 with addition of hexammine cobalt(III) chloride as a precipitant were studied. Scarcely soluble precipitates were formed from respective solutions. Effects of the sulfate, carbonate and precipitant concentration and also of the sulfate solution pH on the precipitations were examined. Composition of the precipitate from H 2 SO 4 was [Co(NH 3 ) 6 ] 2 [Ce(SO 4 ) 5 ]·5H 2 O and that from (NH 4 ) 2 SO 4 more complicated. The relation of compositions to pH of the (NH 4 ) 2 SO 4 solution was studied in detail. The precipitates from solutions of pH lower than 1.7 were [Ce(SO 4 ) 2 ]·α[Co(NH 3 ) 6 ] 2 (SO 4 ) 3 · n H 2 O, with α≌0.7, and those from solutions of pH higher than this contained OH − .

Separation of Curium from Neutron Irradiated Am-241

The conditions under which curium can be separated from irradiated 241Am target were elucidated. The isolation process consists of three steps: In the first step, Am(III) is oxidized to pentavalent state in a dilute nitric acid solution, and then plutonium and curium are extracted from the irradiated target by solvent extraction with HDEHP. Curium in the organic phase is back-extracted with 1 N nitric acid, and thereafter plutonium with a reducing solution containing ferrous sulfamate. The curium is finally purified by cation exchange, using α-hydroxy isobutyrate as the eluting solution. About 0.4 μg of 242Cm and 4×10−3 μg of 243Cm were found in the curium fraction, which had been separated from 1 mg of irradiated 241Am sample.