Keiichi Sekine

Spectrophotometric determination of zirconium, uranium, thorium and rare earths with arsenazo III after extractions with thenoyltrifluoroacetone and tri-n-octylamine

A method is described for the spectrophotometric determination of microgram amounts of zirconium, uranium(VI), thorium and rare earths with Arsenazo III after systematic separation by extraction. First zirconium is extracted into a xylene solution of thenoyltrifluoroacetone (TTA) from about 4M hydrochloric acid. Uranium(VI) is then extracted into a xylene solution of tri-n-octy lamine from about 4M hydrochloric acid. Thorium is next extracted into TTA solution at pH about 1.5, and finally rare earths are extracted into TTA solution at pH about 4.7. Each metal is back-extracted from the organic phase before determination.

Liquid—liquid extraction separation and sequential determination of plutonium and americium in environmental samples by alpha-spectrometry

A procedure is described by which plutonium and americium can be determined in environmental samples. The sample is leached with nitric acid and hydrogen peroxide, and the two elements are co-precipitated with ferric hydroxide and calcium oxalate. The calcium oxalate is incinerated at 450 degrees and the ash is dissolved in nitric acid. Plutonium is extracted with tri-n-octylamine solution in xylene from 4M nitric acid and stripped with ammonium iodide/hydrochloric acid. Americium is extracted with thenoyltrifluoroacetone solution in xylene at pH 4 together with rare-earth elements and stripped with 1M nitric acid. Americium and the rare-earth elements thus separated are sorbed on Dowex 1 x 4 resin from 1M nitric acid in 93% methanol, the rare-earth elements are eluted with 0.1M hydrochloric acid/0.5M ammonium thiocyanate/80% methanol and the americium is finally eluted with 1.5M hydrochloric acid in 86% methanol. Plutonium and americium in each fraction are electro-deposited and determined by alpha-spectrometry. Overall average recoveries are 81% for plutonium and 59% for americium.

Determination of traces of uranium in sea water after separation by froth flotation

SummaryUranium in sea water is separated by froth flotation of the uranium(VI)-Arsenazo III-Zephiramine ion-adduct and then determined by neutron activation or spectrophotometric method using the uranium(IV)-Arsenazo III complex. Results of the analysis of Pacific coastal samples by the two methods are in good agreement; an average value of 3.0μg U per liter was obtained.ZusammenfassungDurch Schaumflotation läßt sich Uran aus Meerwasser in Form des Ionenadduktes U(VI)-Arsenazo III-Zephiramin abtrennen und dann durch Neutronenaktivierung oder spektrophotometrisch als U(IV)-Arsenazo III-Komplex bestimmen. Analysenergebnisse für Proben von der Pazific-Küste stimmen bei beiden Methoden gut überein. Als Durchschnittsergebnis wurden 3,0μg U/Liter gefunden.

Spectrophotometric determination of zirconium in nickel-base alloys with Arsenazo III after separation by froth flotation

Zusammenfassung0,02–0,1% Zirkonium kann spektralphotometrisch mit Arsenazo III in Nickellegierungen bestimmt werden, wenn es zuvor aus der Probelösung durch Schaumfraktionierung mit Arsenazo III und Zephiramin abgetrennt wird. Nickel, Chrom und Eisen stören nicht. Bei der Analyse von Standardlegierungen wurde eine Standardabweichung von 2,2% gefunden.Summary0.02–0.1% of zirconium can be determined in nickel alloys by spectrophotometry with Arsenazo III after its separation from the sample solution by means of froth flotation using Arsenazo III and Zephiramine. Nickel, chromium and iron do not interfere. Analysis of standard alloys yielded a standard deviation of 2.2%.

Separation and spectrophotometric determination of uranium (VI) by extraction with arsenazo III and zephiramine

SummaryMicrogram quantities of uranium(VI) can be determined at 655 nm after separation by chloroform extraction of its Arsenazo III complex with Zephiramine. The extracted uranium can be back-extracted with an aqueous solution of ammonium carbonate. Uranium can be separated from aluminium, iron(II), and some other elements. Probably the same species, i. e., the ion association compound between the uranium (VI)-Arsenazo III complex and Zephiramine are involved during the extraction and the froth flotation.ZusammenfassungMikrogrammengen Uran(VI) lassen sich nach Chloroformextraktion seines Arsenazo-III-Komplexes mit Zephiramin bei 655 nm messen. Das extrahierte Uran kann man mit wäßriger Ammoniumcarbonatlösung rück-extrahieren. Von Aluminium, Eisen(II) und einigen anderen Elementen kann es so getrennt werden. Wahrscheinlich handelt es sich bei der Extraktion und der Schaumflotation um die gleiche Ionenassoziatverbindung des Uran (VI)-Arsenazo-III-Komplexes mit Zephiramin.

Froth flotation separation of small amounts of thorium by means of Arsenazo III and Zephiramine

ZusammenfassungDer Komplex aus Thorium und Arsenazo III wird aus 0,3 M salzsaurer Lösung in Gegenwart der quaternären Ammoniumverbindung Zephiramin durch Schaumfraktionierung abgetrennt. Der Einfluß der Konzentrationen an Arsenazo III, Zephiramin, Säure und Fremdionen wurde untersucht. Die Thoriumbestimmung erfolgt spektralphotometrisch mit Arsenazo III. Die Anwendung auf die Trennung von Kernspaltprodukten wird beschrieben.SummaryA method is described for the separation of microgram amounts of thorium by means of froth flotation. The thorium-Arsenazo III complex is concentrated from 0.3 M hydrochloric acid solution into the scum in the presence of a quaternary ammonium compound, Zephiramine, which acts as a cationic surfactant. Effects of Arsenazo III concentration, Zephiramine concentration, acidity, and foreign ions have been studied. Thorium is determined spectrophotometrically with Arsenazo III. Behaviour of selected fission-product nuclides during systematic flotation separation has also been studied.

Measurement of Uranium Series Radionuclides in Rock and Groundwater at the Koongarra ore Deposit, Australia, by Gamma Spectrometry

Gamma spectrometry without any self-absorption correction was developed to measure low energy gamma rays emitted by uranium and actinium series radionuclides in rock samples and groundwater residues collected at the Koongarra ore deposit, Australia. Thin samples were prepared to minimize the self-absorption by uranium in the samples. The present method gave standard deviations of 0.9 to 18% for the measurements of concentrations of uranium and actinium series radionuclides. The concentrations of {sup 238}U, {sup 230}Th and {sup 235}U measured by gamma spectrometry were compared with those by alpha spectrometry that requires a complicated chemical separation procedure. The results obtained by both methods were in fairly good agreement, and it was found that the gamma spectrometry is applicable to rock and groundwater samples having uranium content sup to 8.1% (10{sup 3} B1/g) and 3 Bq/l of {sup 238}U, respectively. The detection limits were calculated to be of the order of 10{sup {minus}2} Bq/g for rock samples and 10{sup {minus}1} Bq/l for groundwater samples. The concentrations of uranium and actinium series radionuclides can be determined precisely in these samples using gamma spectrometry without any self-absorption correction.

DISTRIBUTIONS OF URANIUM-SERIES RADIONUCLIDES IN ROCK AND MIGRATION RATE OF URANIUM AT THE KOONGARRA URANIUM DEPOSIT, AUSTRALIA

Horizontal distributions and depth profiles of uranium-series radionuclides were investigated by alpha and gamma spectrometry for 206 rock samples from the Koongarra uranium deposit, Australia, to discuss the migration behavior of radionuclides in the weathering system. From the horizontal distributions of uranium and activity ratios of U/U and Th/ U, the direction of uranium migration was determined to be southward from the secondary orebody. Uranium leaching has occurred up-gradient and down-gradient of the secondary orebody, but uranium in the secondary orebody has not moved at least past 0.35 My based on the depth profiles of Th/U activity ratios. In the deeper region, leaching and deposition of uranium have occurred up-gradient and down-gradient of the primary orebody, respectively. The proportion of uranium retained over 1—3 My was estimated to be a minimum of 38% relative to the amount of uranium existing before commencement of uranium migration by comparing the amount of uranium in the weathered zone with that in the unweathered zone.

Migration Behavior of Uranium Series Nuclides in Altered Quartz-Chlorite Schist

The migration behavior of uranium series nuclides in an altered quartz-chlorite schist has been studied by utilizing data on the activity distributions of uranium series nuclides at Koongarra in the Northern Territory of Australia. The variation of 230 Th/ 234 U activity ratios (ARs) with distance along surface (2 m depth), intermediate (16 m) and deep (31 m) layers show different trends in the three layers parallel to the water flow. The relationship between the 234 U/ 238 U and 230 Th/ 238 U ARs reveals that the mobility of the uranium series nuclides is in order 238 U, 234 U and 230 Th, and that the retardation factors oft 234 U are greater than those of 238 U by a factor of 1.1, 1.9 and 1.0 in the surface, intermediate and deep layers, respectively. X-ray diffraction patterns show different mineral assemblages, which are the alteration products of chlorite at the three layers. These results imply that the migration behavior of uranium series nuclides at each depth would be related to the alteration of chlorite.

Purification of arsenazo III by gel chromatography

vanadium were not satisfying in that regard, a procedure had been worked out using vanadium (V) for the determination of N-substituted hydroxamic acids (in this case N-ptolylbenzohydroxamic acid, p-TBHA). Optimum conditions were studied in detail and are incorporated in the below described working instruction. The composition of the complex involved is V: p-TBHA = 1:2. Molar absorptivities in terms of p-TBHA and vanadium are 2350 and 4700 1 .mo le l cm -1 at the absorption maximum of 530nm, respectively. Molar absorptivity in terms of p-TBHA is numerically just half the molar absorptivity reported in terms of vanadium. It is, therefore, concluded that the recovery ofpTBHA as its vanadium (V) complex under the optimum recommended conditions of its determination is 100%. Optimum range is 19-671ag/ml of p-TBHA. Beers law is obeyed. The reaction is practically specific for N-substituted hydroxamic acids and is superior to other methods with regard to selectivity and sensitivity. Procedure. Extract p-TBHA from the aqueous solution with 10,5 and 5 ml portions of chloroform, mix 10 ml of such an extract with 2 ml of conc. hydrochloric acid and 4ml of saturated solution of ammonium metavanadate and shake vigorously. Separate the violet extract, dry it over 1 2 g of anhydrous sodium sulphate and transfer into a 25mi volumetic flask. Shake the aqueous phase again with a second 5 ml portion of chloroform, extract and transfer into the same flask. Repeat with a third 5 ml portion. Make the combined extracts upto the mark and measure the otpical density at 530 nm with chloroform as blank.