Liquid-liquid extraction and separation studies of uranium(vi)

Summary Separation of uranium(VI) from iron(III), molybdenum(VI), vanadium (V), bismuth(III), zirconium(IV) and thorium(IV) is achieved by liquid-liquid extraction with 4-methyl-3-pentene-2-one (mesityl oxide; MeO) from sodium salicylate media (0.1M, pH 6.0). The extracted species is UO₂(HO·C₆H₄COO)₂·2MeO. A procedure for separating 50g of uranium from mg amounts of the other metals is described.

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Flüssig-flüssig-Extraktion und Trennung von Uran(VI)

Zusammenfassung Die Trennung des U(VI) von Fe(III), Mo(VI), V(V), Bi(III), Zr(IV) und Th(IV) läßt sich durch Flüssig-flüssig-Extraktion mit 4-Methyl-3-penten-2-on] (Mesityloxid, MeO) aus 0,1M Natriumsalicylat bei pH 6,0 durchführen. Die extrahierte Verbindung ist UO₂(HO·C₆H₄COO)2·2MeO. Ein Verfahren zur Abtrennung von 50g Uran von Milligrammengen der anderen Metalle wurde beschrieben.

     

Spectrophotometric determination of uranium(VI) using a synergic mixture of ethyl acetoacetate and pyridine

A method is proposed for the extractive spectrophotometric determination of uranium(VI) using the synergic combination of ethyl acetoacetate (EAA) and pyridine (Py) as extractants. The optimum conditions have been evaluated by varying pH and ethyl acetoacetate and pyridine concentration. The nature of the extracted species has been determined by 1g D-1g C plots and the extracted species was found to be UO₂(EAA)₂.Py. The method has been applied for the separation and determination of uranium(VI) from synthetic mixtures.     

Validated Chiral LC Method for the Enantiomeric Separation of β-Amino-β-(3-Methoxyphenyl) Propionic Acid

A chiral liquid chromatographic method for enantiomeric resolution of β-amino-β-(3-methoxyphenyl) propionic acid was developed and validated. The “hybrid” π-electron donor–acceptor based stationary phase (R,R) Whelk-01 was found to be enantiomerically selective for (R) and (S) enantiomers of β-amino-β-(3-methoxyphenyl) propionic acid with a resolution greater than 2.0. The effects of isopropyl alcohol and ethanol on enantioselectivity and resolution of enantiomers were evaluated. Calibration curves were linear over the range of 0.10–1.00, with a regression coefficient (r) of 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were 300 and 1,000 ng mL⁻¹ respectively for 10 μL injection volume. The percentage RSD of the peak area of six replicate injections of (S) enantiomer at LOQ concentration was 2.8. The percentage recovery of (S) enantiomer from (R) enantiomer samples ranged from 92 to 102. The test solution was observed to be stable up to 24 h after the preparation. The developed normal phase chiral LC method can be used for the enantiomeric purity evaluation of R-β-amino-β-(3-methoxyphenyl) propionic acid.     

Extraction and separation of scandium salicylate with triphenylphosphine oxide

Scandium can be extracted from 5.0 × 10^–2 mol/l sodium salicylate solution, adjusted to pH 4.0–5.0 with 0.5% triphenylphosphine oxide dissolved in toluene as an extractant. After stripping from the organic phase with 0.5 mol/l HCl it can be subsequently determined spectrophotometrically with Alizarin Red S. The method permits a separation of Sc(III) from Ti(IV), V(V), Cr(VI), Fe(III), Y(III), La(III), Ce(III), Nd(III) and Sm(III) in synthetic mixtures. The method is fast, simple and selective. Received: 6 May 1996 / Revised: 21 July 1996 / Accepted: 25 July 1996     

Performance of immobilized Saccharomyces cerevisiae in the removal of long lived radionuclides from aqueous nitrate solutions

The efficiency of tailor made immobilized Saccharomyces cerevisiae(biomatrix) for the sorption of radionuclides ²³³U, ²³⁹Pu, ²⁴¹Am, ¹³⁷Ce, ¹⁴⁴Cs, ^103,106Ru and ⁹⁰Sr from aqueous nitrate solutions at different pH was studied. Effect of ionic strength, anionic components, initial metal concentration and particle size of the biomatrix on the sorption of metal ions were investigated. At pH in the range of 1 to 2 more than 95% sorption of U, Pu, Am and Ce could be accomplished, while that of Ru was 65%. Sorption of Cs and Sr were negligible under similar conditions. The metal ion-biomatrix system for Pu, Am and Ce reached equilibrium within 60 minutes. In the case of U, equilibrium attained in 100 minutes. The presence of anionic components, Cl^-, C₂O₄ ^2-, CH₃COO^-, NO₃ ^- and SO₄ ^2- (up to 0.5 mol^.dm^-3 of their individual concentration) in the aqueous solutions has no effect on the sorption of Pu by the biomatrix. Sorption of U, Pu, Am were observed in the presence of several cationic impurities such as Al, Be, Cd, Cr, Fe, Mn, Pb, Ce, Dy, Eu, Gd and Sm. Metal sorbed on the biomatrix could be leached out using 5 mol^.dm^-3 nitric acid. The I.R spectra of U bearing biomatrix suggest chemical interaction of uranyl ion with the biomatrix.     

Extraction study of uranium(VI) and thorium(IV) salicylates with triphenylarsine oxide

Triphenylarsine oxide is proposed as an extractant for the solvent extraction of uranium and thorium salicylates. The optimum extraction conditions are established by studying the various parameters such as pH, sodium salicylate concentration, triphenylarsine oxide concentration, diluents and shaking time. The probable extracted species as ascertained by logD-logC plots are UO₂(Hsal)₂·2TPAsO and Th(Hsal)₄·2TPAsO. The method is simple, fast, precise and permits the determination of uranium and thorium in monazite sand samples.     

Amphitropic liquid crystals. Two lamellar phases in a surfactant containing thermotropic and lyotropic mesogenic groups

Abstract

We have studied the lyotropic liquid-crystalline behaviour of cationic surfactants containing a potentially thermotropic moiety, a terminal cyanobiphenyloxy group. Both mono-alkyl and mid-chain substituted dialkyl surfactants have been examined using optical microscopy and NMR spectroscopy. Incorporation of the cyanobiphenyloxy group destabilizes the hexagonal and bicontinuous cubic phases, with only an extensive lamellar region being observed. For the dialkyl surfactant there is a range of compositions where two lamellar phases co-exist, one water-rich and the second surfactant-rich.     

One-Pot Palladium-Catalyzed Ligand- and Metal-Oxidant-Free Aerobic Oxidative Isocyanide Insertion Leading to 2-Amino-substituted-4(3H)-quinazolinones

An efficient, ligand- and metal-oxidant-free, one-pot, cascade aerobic oxidative, palladium-catalyzed, multicomponent reaction has been developed through isocyanide insertion of less active secondary amide and aromatic amine, which leads to 2-amino-substituted-4(3H)-quinazolinones. This approach proves to be one of the simplest methods for the synthesis of this class of valuable bioactive heterocyclic scaffolds.     

Anticancer Activity of Hydrogen‐Bond‐Stabilized Half‐Sandwich RuII Complexes with Heterocycles

Neutral half‐sandwich organometallic ruthenium(II) complexes of the type [(η⁶‐cymene)RuCl₂(L)] ( H1 – H10 ), where L represents a heterocyclic ligand, have been synthesized and characterized spectroscopically. The structures of five complexes were also established by single‐crystal X‐ray diffraction confirming a piano‐stool geometry with η⁶ coordination of the arene ligand. Hydrogen bonding between the N? H group of the heterocycle and a chlorine atom attached to Ru stabilizes the metal–ligand interaction. Complexes coordinated to a mercaptobenzothiazole framework ( H1 ) or mercaptobenzoxazole ( H6 ) showed high cytotoxicity against several cancer cells but not against normal cells. In vitro studies have shown that the inhibition of cancer cell growth involves primarily G1‐phase arrest as well as the generation of reactive oxygen species (ROS). The complexes are found to bind DNA in a non‐intercalative fashion and cause unwinding of plasmid DNA in a cell‐free medium. Surprisingly, the cytotoxic complexes H1 and H6 differ in their interaction with DNA, as observed by biophysical studies, they either cause a biphasic melting of the DNA or the inhibition of topoisomerase IIα activity, respectively. Substitution of the aromatic ring of the heterocycle or adding a second hydrogen‐bond donor on the heterocycle reduces the cytotoxicity.     

Eco‐friendly,ultrasound‐assisted,and facile synthesis of one‐pot multicomponent reaction of acridine‐1,8(2H,5H)‐diones in an aqueous solvent

A one‐pot, multistep synthesis of acridine‐1,8(2H,5H)‐diones ( 4a–m ) was achieved by three‐component reaction of dimedone ( 1 ) with an aromatic aldehyde ( 2a–m ) and an ammonium acetate ( 3 ) using water as a green solvent without any catalyst and a simple, easily handled, and ultrasonic technique as well as conventional method.