Separation and determination of uranium(VI) with calixarene hydroxamic acids

A new calixarene hydroxamic acid, 5,11,17,23-tetra-(N-p-chlorophenyl hydroxamate c-phenyl-25,26,27,28-tetrahydroxycalix[4]arene (CPCHA) was synthesized and used for the extraction and spectrophotometric determination of uranium(VI). The molar absorptivity of the uranium(VI)-CPCHA-thiocyanate complex was 9.9·10³ 1·mol^–1·cm^–1 at 436 nm. The system obeyed Beer's law in the range of 1.78–23.1 ppm of uranium. The uranium(VI)-hydroxamate-ethyl acetate complex was directly aspirated for graphite furnace atomic absorption spectrometry measurements (GFAAS) which increased the sensitivity by about a factor of fifty. Uranium was determined in various standard and environmental samples.     

Extraction and spectrophotometric determination of uranium in phosphate fertilizers

An extraction and spectrophotometric method for determination of trace amounts of uranium in phosphate fertilizers is described. It is based on the extraction of uranium with trioctylphosphine oxide in benzene and the spectrophotometric determination of uranium with Arsenazo III in buffer-alcoholic medium. The maximum absorbance occurs at 655 nm with a molar absorptivity of 1.2·10⁴ l·mol^–1·cm^–1. Beer's law is obeyed over the range 0.6–15.0 g·ml^–1 of uranium(VI). The proposed method has been applied successfully to the analysis of phosphate fertilizers with phosphate concentrations of 45% P₂O₅.     

Spectrophotometric determination of plutonium with chlorophosphonazo III

Summary Plutonium(IV) forms a Chlorophosphonazo III complex in 0.5–2M hydrochloric acid. Maximum absorbance occurs at 620 and 685 nm. Beer's law is obeyed over the range of 0–50g per 10 ml and the molar absorptivity is 3.7×10⁴ mol^–1 cm^–1 at 690 nm. Plutonium can be determined in the presence of fluoride, sulfate and phosphate. However, lanthanides, thorium, uranium and zirconium interfere seriously.

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Zusammenfassung Plutonium(IV) bildet in 0,5-bis 2-m Salzsäure mit Chlorphosphonazo III eine Komplexverbindung, deren Absorptionsmaxima bei 630 und 685 nm liegen. Bis 50 g/10 ml entspricht die Farbe dem Beer'schen Gesetz; die molare Extinktion bei 690 nm beträgt 3,7·10⁴l·Mol^–1·cm^–1. Plutonium kann damit in Gegenwart von F^–, SO₄ ^2– und PO₄ ^3– bestimmt werden. Lanthanide, Th, U und Zr stören jedoch ernstlich.

     

Reversed-phase partition chromatographic separation of minor actinides with bis(2-ethylhexyl) sulfoxide from acidic nitrate PUREX waste solutions

The uptake behavior of U(VI), Pu(IV), Am(III) and a few long-lived fission products from nitric acid media by bis(2-ethylhexyl) sulfoxide (BESO) adsorbed on Chromosorb has been studied U(VI), Pu(IV) and Zr(IV) are taken up appreciably as compared to trivalent actinides/lanthanides including some coexisting fission product contaminants which are weakly sorbed on the column. Chromosorb could be loaded with (1.12±0.03) g of BESO per g of the support. Maximum sorption is observed around 4–5 mol·dm^–3 HNO₃ for both U(VI) and Pu(IV), which are sorbed as their disolvates. The elution of (U(VI) and Pu(IV) from the metal loaded sorbent has also been optimized. Desorption of U(VI) is easily accomplished with dilute nitric acid (ca. 0.01 mol·dm^–3)while Pu(IV) is reductively stripped with 0.1 mol·dm^–3 NH₂OH·HCl. Effective sequential separation of U(VI), Pu(IV) and Am(III) from their several admixtures could be readily achieved from real medium and low level active acidic process raffinates.     

Voltamperometric determination of uranium and plutonium in alkaline solutions

The simultaneous determination of U(VI), Pu(VI), Pu(V) in 0.5–4.0 M NaOH has been elaborated by means of classical and differential pulse voltamperometry. U(VI) is determined with a dropping mercury electrode (DME) at the half-wave potential of E_1/2=–0.89 V vs. Ag/AgCl reference electrode due to reduction to U(V). The limiting current or peak heights are proportional to uranium(VI) concentration in the range of 1.3.10^–7–3·10^–4 M U(VI). Deviation from proportionality is observed for higher concentrations due to polymerization of uranates. Pu(VI) and Pu(V) are determined with a platinum rotating electrode at E_1/2=–0.02 V due to the reaction Pu(VI)+e^–»Pu(V) and with DME at E_1/2=–1.1 V due to the reduction to Pu(III). The limiting currents of both Pu(VI) and Pu(V) are proportional to their concentrations in the range of 4·10^–6–1.2·10^–3 M Pu. The determination of U(VI), Pu(VI), Pu(V) is not interfered by the presence of the following salts: 2M NaNO₃, 2M NaNO₂, 1.5M NaAlO₂, 0.5M NaF and ions of Mo(VI), W(VI), V(V), Cu(II). The presence of CrO ₄ ^2– and FeO ₂ ^– ions disturbs the determination of U(VI) in 1–4M NaOH, however, contribution of the reaction Fe(III)+e^–»Fe(II) to uranium reduction peak can be calculated from the height of the second peak Fe(II)+2 e^–»Fe(0).     

A gas-jet system for the study of short-lived,light fission products

A selective method for the solvent extraction and spectrophotometric determination of uranium(VI) is described. Uranium can be extracted into chloroform at pH 6.0 with N-m-chlorophenyl-2-theno-hydroxamic acid (N-m-CPTHA) and determined by spectrophotometry using 1-(2-pyridylazo)-2-naphthol (PAN). The molar absorptivity is 1.50·10⁴ 1·mol^–1·cm^–1 at 560 nm. The system obeys Beer's law within the range 0.95–20.00 ppm of uranium. Alternatively, a back-extraction procedure was also developed in which uranium is back-extracted by nitric acid and estimated spectrophotometrically using Arsenazo III. The molar absorptivity is 2.0·10⁴ 1·mol^–1·cm^–1 at 665 nm. The parameters concerning the optimum conditions for the analytical method are discussed. The proposed method is applied precisely for the determination of uranium in rock and sea water samples.     

Solvent extraction and spectrophotometric determination of titanium (IV) with 3-phenyl-3-methyl-2-mercaptopropenoic acid by use of the synergistic effect of pyridine

Summary The distribution equilibria of 3-phenyl-3-methyl-2-mercaptopropenoic acid (PhMMP), pyridine and the titanium (IV)-PhMMP complex in the presence of pyridine have been studied in the chloroform-water system. An extraction-photometric method for the determination of micro amounts of titanium has been developed. The synergistic effect of pyridine, and the influence of pH, the reagent concentration and the presence of electrolytes and masking agents on the equilibrium have been determined. From slope analysis of the distribution curves, the composition of the extracted species has been found to be Ti(OH)₂(HR)₂·py. The complex is extracted quantitatively. Beer's law is obeyed over the range 0.09–4.30g/ml titanium (IV) and the molar absorptivity is 1.30×10⁴1·mole^–1·cm^–1 at 447 nm. The method has been applied to the determination of titanium in ceramics.

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Über die Extraktion und spektrophotometrische Bestimmung von Titan(IV) mit 3-Phenyl-3-methyl-2-mercaptopropensäure mit Hilfe der synergistischen Wirkung des Pyridins

Zusammmenfassung Das Verteilungsgleichgewicht von 3-Phenyl-3-methyl-2-mercaptopropensäure (PhMMP), Pyridin und Titan-PhMMP-Komplex in Gegenwart von Pyridin wurde in einem Wasser-Chloroform-System untersucht. Eine extraktionsphotometrische Methode für die Bestimmung von Mikromengen Titan(IV) wurde ausgearbeitet. Die synergistische Wirkung des Pyridins sowie der Einfluß des pH, des Reagens und der Gegenwart von Elektrolyten und maskierenden Reagenzien in der wäßrigen Phase auf das Gleichgewicht wurden bestimmt. Aus der Richtung der Verteilungskurven wurde für den extrahierten Komplex die Zusammensetzung Ti(OH)₂(HR)₂·py ermittelt. Der Komplex wird quantitativ extrahiert. Das Beersche Gesetz ist von 0,09–4,30g·ml^–1 Ti(IV) erfüllt, der molare Absorptionskoeffizient ist 1,13·10⁴1·mol^–1·cm^–1; die Sandell-Empfindlichkeit beträgt 3,7ng·cm^–2 bei 447 nm. Diese Methode wurde für die Bestimmung von Titan in keramischem Material verwendet.

     

Extraction-spectrophotometric determination of chromium with Nitrotetrazolium Blue

The interaction of Cr(VI) and Nitrotetrazolium Blue has been examined. A 12 NTB (CrO₃Cl)₂ ion-associate is formed and is extractable into 1,2-dichloroethane. The optimum conditions have been established. The molar absorptivity at 260 nm was (8.2 ± 0.06) × 10⁴L mol^–1cm^–1. Beer's law was obeyed in the range 0.01–0.4 g ml^–1 Cr(VI). A sensitive and selective method for determination of micro-quantities of Cr(VI) in soils and steels is suggested.     

Rapid extraction and photometric determination of cerium(IV) with N-p-tolylbenzohydroxamic acid (p-TBHA)

Summary A method for rapid extraction and spectrophotometric determination of cerium (IV) is described. The cerium-N-p-tolylbenzo-hydroxamic acid complex is extracted into chloroform at the pH 8.4 to 9.8. Maximum absorbance occurs between 460 and 470 nm. The values are reproducible at 465 nm and Beer's law is obeyed at this wavelength over the range of 0.03–40, per ml of the cerium(VI). The molar absorptivity of the cerium-p-TBHA complex is 4.6×10³ l · mole^–1 · cm^–2 at 465. An attempt has been made to determine the cerium in sea water.

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Zusammenfassung Eine Methode zur schnellen Extraktion und spektrophotometrischen Bestimmung von Cer(IV) wurde beschrieben. Der Cer-Komplex mit N-p-Tolylbenzohydroxamsäure wird bei pH 8,4–9,8 mit Chloroform extrahiert. Das Absorptionsmaximum liegt zwischen 460 und 470 nm. Bei 465 nm sind die Ablesungen reproduzierbar und wird das Beersche Gesetz zwischen 0,03 und 40g Cer/ml erfüllt. Die molare Extinktion des genannten Komplexes beträgt bei 465 nm 4,6 · 10³ l · mol^–1 · cm^–2. Es wurde versucht, den Cergehalt von Meerwasser zu bestimmen.

     

Direct and Derivative Spectrophotometric Determination of Thorium with 2,4-dihydroxybenzaldehyde Isonicotinoyl Hydrazone

A simple and sensitive spectrophotometric method is developed for the determination of throium in aqueous medium. The metal ion forms yellow coloured complex with 2,4-dihydroxybenzaldehyde isonicotinoyl hydrazone (2,4-DHBINH) in the pH range 2.0–8.0. The complex shows an absorption maximum at 390 nm. The absorbance of the complex is maximum at pH 5.5 Beer's law is obeyed in the range 0.30–7.00 g/ml of thorium(IV). The molar absorptivity and the Sandell's sensitivity of the method are 2.20· 10⁴ l·mol^–1·cm^–1 and 0.0106 g/cm^–2, respectively. The interference of various ions was studied. The composition of the complex is 1:1 {Th(IV) : 2,4-DHBINH}. The first derivative spectrum of the complex shows a zero cross at 391.2 nm and maximum amplitude at 415 nm. Thus a sensitive derivative spectrophotometric method for the determination of Th(IV) is proposed.     

Extraction of uranium (VI), plutonium (IV) and some fission products by tri-iso-amyl phosphate

The extractive properties of tri-isoamyl-phosphate (TAP), an indigenously prepared extractant, and the loading capacity of extraction solvent containing TAP for U(VI) and Pu(IV) ions in nitric solution have been investigated. The dependence of the distribution ratio on the concentration of nitric acid showed that TAP has an ability to extract these actinides, while the fission product contaminants are poorly extracted. The distribution data revealed a quantitative extraction of both U(VI) and Pu(IV) from moderate nitric acidities in the range 2–7 mol · dm^–3. Slope analysis proved predominant formation of the disolvated organic phase complex of the type UO₂(NO₃). 2TAP and Pu(NO₃)₄·2TAP with U(VI) and PU(IV), respectively. On the contrary, the extraction of fission product contaminants such as¹⁴⁴Ce,¹³⁷Cs,⁹Nb.,¹⁴⁷Pr,¹⁰⁶Ru,⁹⁵Zr was almost negligible even at very high nitric acid concentrations in the aqueous phase indicating its potential application in actinide partitioning. The recovery of TAP from the loaded actinides could be easily accomplished by using a dilute sodium carbonate solution or acidified distiled water (0.01 mol · dm^–3 HNO₃) as the strippant for U(VI) and using uranous nitrate or ferrous sulphamate as that for Pu(IV). Radiation stability of TAP was adequate for most of the process applications.     

Solvent extraction of molybdenum(VI) with 1-Phenyl-2-methyl-3-hydroxy-4-pyridone

Summary The extraction of molybdenum(VI) from aqueous hydrochloric or perchloric acid solution by 1-phenyl-2-methyl-3-hydroxy-4-pyridone (HX) dissolved in chloroform has been studied. Molybdenum(VI) is quantitatively extracted from aqueous solution in the range 0.001–1M hydrogen ion concentration. Outside this range, the extraction of molybdenum decreases and at 10M acid concentration or at pH>6 practically all the molybdenum remains in the aqueous phase. Molybdenum can be stripped with 10M HCl. The composition of the extracted molybdenum(VI) species was found to be MoO₂X₂. This complex, dissolved in chloroform, has a maximum absorbance at 317 nm and a molar absorptivity of 2.5×10⁴ 1 · mole^–1 · cm^–1. Owing to this property, molybdenum can be determined spectrophotometrically directly in the organic phase.

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Zusammenfassung Die Extraktion von Mo(VI) aus wäßriger Salzsäure oder Perchlorsäure mit 1-Phenyl-2-methyl-3-hydroxy-4-pyridon (HX) in chloroformischer Lösung wurde untersucht. Sie erfolgt quantitativ bei 0,001–1-molarer H-Ionenkonzentration. Außerhalb dieses Bereiches fällt die Extraktionsrate ab und aus 10-m Säure bzw. bei pH>6 bleibt praktisch alles Molybdän in der wäßrigen Phase. Mit 10-m Salzsäure kann man Mo abtrennen. Die Zusammensetzung der extrahierten Mo-Verbindung entspricht der Formel MoO₂X₂. Dieser in Chloroform gelöste Komplex hat ein Absorptionsmaximum bei 317 nm und eine molare Extinktion von 2,5 · 10⁴l · Mol^–1 cm^–1. Demzufolge läßt sich Molybdän unmittelbar in der organischen Phase spektrophotometrisch bestimmen.

     

Speciation of Pu ions by differential pulse polarography

By means of differential pulse polarography, Pu ions of different oxidation states have been investigated in 1M Na₂CO₃ solution. Redox reactions of Pu/III/, Pu/IV/, Pu/V/ and Pu/VI/, which are mostly of irreversible nature, have been observed within the potential range of the dropping mercury electrode /DME/, from 0 to –1.5 V, against a Ag/AgCl/NaCl (3M) reference electrode. Based on the peak potential observed for each reaction, the stability of a given oxidation state in the solution could be ascertained. The redox potential of the Pu/IV/–Pu/III/ pair, which was found to be –1.0 V, indicated that the Pu/IV/ carbonate complex was of high stability. The detection sensitivity of the Pu/IV/ ion was found to be 1×10^–6M.     

Spectrophotometric determination of trace amounts of cadmium using Cd(II)-KI-Crystal violet system in the presence of triton X-100 and PVA

A new highly sensitive spectrophotometric method for determination traces of cadmium using Cd-(II)-KI-Crystal Violet system in the presence of Triton X-100-poly(vinyl) alcohol (PVA) mixture has been developed. The apparent molar absorptivity of the system is 1.77 × 10⁵ 1-mol^–1 cm^–1 and its Sandell's sensitivity is 6.35 × 10^–4 g·Cd·cm^2–. Beer's law is obeyed up to 0.32 g·Cd(II)·ml^–1. The method has been applied to determine Cd(II) in waste water, rice and pork meat samples with satisfactory results.     

Ultraviolet spectrophotometric determination of tungsten(VI) with ammonium 1-pyrrolidinecarbodithioate

A simple and rapid ultraviolet spectrophotometric method is proposed for the determination of trace amounts of tungsten(VI) with ammonium 1-pyrrolidinecarbodithioate (APDC). The method is based on measurement of the absorbance of the tungsten APDC complex in fairly concentrated hydrochloric acid medium; no extraction is required. The complex is formed at an initial acidity of 6M hydrochloric acid and has an absorption maximum at 250 nm. The high absorption of the reagent blank at 250 nm disappears on decomposition of excess of reagent by heating. Beer's law is obeyed over the range 0.43–3.2 ppm of tungsten(VI). The molar absorptivity of the complex is 4.5 × 10⁴ l.mole⁻¹ .cm⁻¹ at 250 nm. Tenfold amounts of aluminium, magnesium, calcium, cobalt, iron(II), lead, silver, sodium and titanium do not interfere in the determination of 50 μg of tungsten (VI).     

A sensitive spectrophotometric method for the determination of trace amounts of uranium(VI) using 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone

The reaction between uranium(VI) and 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone (2HNAINH) has been investigated in HCl-sodium acetate buffers and a highly sensitive and simple procedure for the determination of uranium(VI) is suggested. The orange red colored complex showed maximum absorption at 430 nm in buffer solutions of pH 3. Beer's law is obeyed in the range of 0.2 to 33 g ml^–1. The molar absorptivity and Sandell's sensitivity are found to be 9.6×10³ mol·l^–1 and 0.025 g cm^–2, respectively. The composition of the complex between metal and reagent is found to be 11. The effect of diverse ions is also studied and the method is successfully applied for the determination of uranium in synthetic mixtures.     

Ultraviolet spectrophotometric determination of tellurium

Summary An ultraviolet spectrophotometric method for the determination of tellurium is proposed which is based on the formation of tetrakis-1-pyrrolidinecarbodithioate tellurium(IV) which is extractable with chloroform. Conformity to Beer's law was observed. The molar absorptivity at 257 nm is 8.12 · 10⁴ 1. mole^–1, cm^–1.

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Zusammenfassung Ein UV-spektrophotometrisches Verfahren für die Bestimmung von Tellur wurde vorgeschlagen, das auf der Reaktion von Te(IV) mit vier Äquivalenten 1-Pyrolidindithiocarbamat und der Extraktion des Reaktionsproduktes mit Chloroform beruht. Das Beersche Gesetz ist erfüllt. Die molare Extinktion bei 257 nm beträgt 8,12 · 10⁴ 1.Mol^–1.cm^–1.

     

Spectrophotometric determination of aluminium with Chromal Blue G in the presence of cetyltrimethylammonium chloride

Summary Spectrophotometric Determination of Aluminium with Chromal Blue G in the Presence of Cetyltrimethylammonium Chloride Chromal Blue G (C. I. 43835) in the presence of cetyltrimethylammonium chloride is proposed for the spectrophotometric determination of microgram amounts of aluminium. The stoichiometric ratio of aluminium to Chromal Blue G is 14. Beer's law is obeyed from 0.01 to 0.16 ppm of aluminium. The molar absorptivity is 1.62×10⁵1·mole^–1·cm^–1 at 660 nm.     

Microdetermination of bromate ions with antipyrine

Summary A spectrophotometric method for the micro-determination of bromate ions has been described. A red colored complex is obtained when 3 ml of 5% antipyrine, 3 ml of 60% perchloric acid and 1 ml of 0.1M sodium nitrite solution are added in a solution containing bromate ions. The maximum absorbance occurs at 525 nm. Beer's law is obeyed for solutions containing 25.0–140.0/ml of bromate ions. Sensitivity has been found to be 0.029g BrO₃ ^–/cm² for logI ₀/I=0.04 with a molar absorptivity of 2·10³ moles^–1, cm^–1. liter. As(III), Ce(IV), Fe(III), CrO₄ ^2–, Cr₂O₇ ^2–, and Cl^– interfere in the determination.

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Zusammenfassung Eine spektrophotometrische Methode zur Mikrobestimmung von Bromationen wurde beschrieben. Nach dem Zusatz von 3 ml 5%iger Antipyrinlösung, 3 ml 60% iger Perchlorsäure und lml 0,1 ·m Natriumnitrit zu einer bromathaltigen Lösung erhält man eine rot gefärbte Komplexverbindung. Deren Absorptionsmaximum liegt bei 525 nm. Lösungen mit 25,0 bis 140,0g Bromat/ml entsprechen dem Beerschen Gesetz. Die Empfindlichkeit der Reaktion beträgt 0,029g BrO₃ ^–/cm₂ für logI ₀/I=0,04 mit einer molaren Absorption von 2 · 10³ m^–1 · cm^–1 · 1. As(III), Ce(IV), Fe(III), CrO₄ ^2–, Cr²O₇ ^2– und Cl^– stören die Bestimmung.

     

Study on the colour reaction of Te-KI-RhB system in the presence of PVA-OP

A new supersensitive spectrophotometric method for the determination of tellurium (IV) has been developed which is based on the formation of an ion-association complex with potassium iodide and rhodamine B (RhB) in the presence of polyvinyl alcohol (PVA) and polyethylene glycol octyl phenyl ether (OP). The molar absorptivity at 560 nm is 2.8 × 10⁶ 1 mol^–1 cm^–1. Beer's law is obeyed over the range of 20–70 ng/ml Te. The method has been applied successfully to determine tellurium in alloy, steel and some other samples.