Determination Of Rhenium Research Articles

Gravimetric determination of rhenium as 2,4,6-triphenylpyrylium perrhenate

A gravimetric method for determination of rhenium is based on formation of sparingly soluble 2,4,6-triphenylpyrylium perrhenate. The conditional solubility product in O.1 N sulphuric acid medium was found to be (3.72 ± 0.08) × 10 −9. The interference of foreign anions (simple or complex) is eliminated by preliminary extraction of perrhenate with acetone from strongly alkaline medium. The method is applied to the determination of rhenium in perrhenates and rhenium alloys.

Spectrophotometric Determination of Rhenium with N-(4-Methoxy-phenyl)-α-thiopicolinamide and Evaluation of the Stability Constant of the Complex Involved Therein

Spectrophotometric Determination of Rhenium with N-(4-Methoxy-phenyl)-α-thiopicolinamide and Evaluation of the Stability Constant of the Complex Involved Therein

Spectrophotometric determination of rhenium in alkaline solution

The reaction of perrhenate with hydroxylammonium chloride (NH3OHCl) has been studied. Hydroxylammonium chloride reacts with rhenium in 8–10 M sodium hydroxide solution to produce a yellow complex which has λmax. at 300 nm with a molar absorptivity of 7.9 × 103 l mol–1 cm–1. The stoicheiometry of the complex has been studied spectrophotometrically using different procedures. A method for the spectrophotometric determination of rhenium has been developed, and this has been applied to the determination of rhenium in molybdenum-rhenium and tungsten-rhenium alloys.

Determination of rhenium based on the formation of rhenium(VI) oxide halide complexes by spectrophotometry and electron spin resonance spectroscopy

The possibility of obtaining solutions of rhenium(VI) compounds and their analytical applications has been studied. The rhenium(VI) compounds formed, ReOCl5– and ReOBr4, are characterised by specific absorbance spectra and electron spin resonance (ESR) spectra. New quantitative methods of rhenium determination were devised. The formation of ReOBr4 in sulphuric acid from the ReO4– ion and KBr was used for the development of a selective spectrophotometric method for the determination of rhenium and the ability of ReOBr4 to be extracted into organic solvents was used for rhenium determination by ESR.On the basis of ReOCl5– formation, a quantitative method for the determination of rhenium by the spectrophotometric titration of ReO4– in a mixture of sulphuric and hydrochloric acids using an iron(II) solution was devised. The methods were also applied to alloys.

Determination of rhenium by substoichiometric pseudoisotopic dilution analysis with technetium-99 and liquid scintillation counting

Determination of rhenium by substoichiometric pseudoisotopic dilution analysis with technetium-99 and liquid scintillation counting

Improvement of the extractionspectrophotometric thiocyanate method for the determination of rhenium by addition of imipramine

Improvement of the extractionspectrophotometric thiocyanate method for the determination of rhenium by addition of imipramine

Spectrophotometric determination of rhenium with di(2-pyridyl)ketone-2-furancarbothiohydrazone and other thiohydrazones

A simple rapid method is proposed for the determination of rhenium (as perrhenate) in which the brown-violet complex produced is measured at 546 nm. The system obeys Beer's law in the range 0.7–14.0 μg Re ml -1; the molar absorptivity is 1.51 × 10 4 l mol -1 cm -1 in ethanol and 1.64 × 10 4 l mol -1 cm -1 for the complex extracted into methyl isobutyl ketone. Molybdenum (100-fold), tungsten (40-fold), copper (10-fold), and palladium (10-fold) are tolerable. Reactions of other metal ions such as Cu(II), Ni(II), Co(II) and Fe(II) with this ligand and reactions of perrhenate with analogous reagents are discussed.

Determination of rhenium in molybdenum concentrates

Determination of rhenium in molybdenum concentrates

Determination of rhenium in the URe 2 binary compound by differential spectrophotometry

A differential spectrophotometric determination of rhenium in its binary compound with uranium is described; the method is based on the action of tin(II) chloride on perrhenate in the presence of dimethylglyoxime with measurement at 445 nm. Uranium does not interfere. For solutions containing about 1 mg of rhenium, the coefficient of variation was 0.08%.

Applications de la colorimetrie de precision a la microanalyse elementaire Dosages du rhenium, du rhodium, du tellure et du zirconium

The sample (< 1 mg) is burnt in an oxygen flask for the determination of rhenium. It is destroyed by a wet process in a Kjeldahl flask for the determination of rhodium or tellurium (sample <4–5 mg) or zirconium (sample <1.5 mg). These elements are determined spectrophotometrically. The following reactions are used: reduction of perrhenate by tin(II) chloride in the presence of 2,2′-furildioxime or thiourea, complexation of rhodium(III) by sodium hypochlorite, formation of iodotellurite, complexation of zirconium(IV) with Xylenol Orange.

Determination of rhenium in geological materials by radiochemical neutron-activation analysis

A neutron-activation method for the determination of rhenium in geological materials is described. Radiochemical separation, using Re-carrier and liquid—liquid extractions, yields 186Re in a state of radiochemical purity. The gamma-ray activity of the radionuclide is counted with an NaI(Tl) crystal scintillation detector, and the chemical yield is determined spectrophotometrically. Results for the contents of rhenium in the standard rock W-1 and in nickeliferous lateritic profiles are reported. Particular problems arising in neutron-activation analysis for rhenium in lunar surface materials are discussed.

A new catalytic reaction of rhenium and its analytical application

Small amounts of perrhenate in fairly concentrated sulphuric acid media and in the presence of tin(II) chloride are found to catalyse the acid hydrolysis of α-furildioxime, with production of a new absorption peak at 320 nm, due to the di-α-furildiketone produced. The catalytically active species is a sulphate complex of rhenium(IV). The catalytic action of rhenium is promoted by citric acid. Rhenium can be determined in the range 0.0005–0.5 μg/ml. Interferences are eliminated by a preliminary extraction. The method has been applied to the determination of rhenium in copper concentrates of low rhenium content, copper ores and rocks. On the basis of the inhibitory effect of molybdenum the reaction can be used for determination of this element as well.

Solvent Extraction and Spectrophotometric Determination of Rhenium(Vll) using Mixed Ligands

Solvent Extraction and Spectrophotometric Determination of Rhenium(Vll) using Mixed Ligands

Separation and determination of rhenium with 5,6-diphenyl-2,3-dihydro(asym)triazine-3-thione

5,6-DiphenyI-2,3-dihydro(asym)triazine-3-thione can be used as a gravimetric reagent for the determination of rhenium (4–50 mg) in the presence of 0.7–1.7 M hydrochloric acid and tin(II) chloride. The composition of the dried complex, which can be weighed directly, is [ReO(C 15H 10N 3S) 2] 2. The method is simple and rhenium can be determined in the presence of a number of foreign ions.

Neutron activation determination of rheumium in rocks and ores after preliminary extraction with pyridine

A simple neutron-activation method for the determination of rhenium based on a preliminary extractive separation of the latter from molybdenum and tungsten is described. The sample is decomposed with sodium peroxide, a small amount of water is added and the resulting pulp is extracted with pyridine. The extract is evaporated to dryness, the residue is dissolved in water and the solution is passed through a column packed with Dowex 50WX8 in H+ form to eliminate the metal impurities. The HReO4 passed, after neutralization with ammonia, is evaporated to dryness in penals, which then are irradiated with thermal neutrons.

Extraction—spectrophotometric determination of rhenium with 5,6-diphenyl-2,3-dihydro(asym)triazine-3-thione

The reagent 5,6-diphenyl-2,3-dihydro(asym)triazine-3-thione produces a green complex with perrhenate in hydrochloric acid medium in presence of stannous chloride. The complex on extraction in chloroform shows a peak at 685 nm. The system obeys Beer's law from 2–10 p.p.m. of rhenium and its molar absorptivity is 1.53-l0-4. It tolerates the presence of a large number of ions, including MoXXX and WXXX. Job's and molar ratio methods suggest that rhenium and the reagent are present in the ratio 1:2 and the isolated complex is of the same composition, i.e. ReO(C25H10N3S)2.

The determination of rhenium on supported systems

A method for the determination of rhenium on various supports is reported in which the separation is carried out without dissolution of the sample. The procedure may also be used when interfering species are present. It is shown that the elaboration of the data allows information to be obtained about the state of the rhenium and its interaction with the support.

Spectrophotometric Determination of Rhenium with Rubeanic Acid

Spectrophotometric Determination of Rhenium with Rubeanic Acid

Spectrophotometric determination of rhenium with thiobenzhydrazide

Spectrophotometric determination of rhenium with thiobenzhydrazide

An extraction-spectrophotometric method for the determination of rhenium using mixed ligands

A new method is proposed for the extraction and spectrophotometric determination of rhenium using thiocyanate and thiourea as mixed ligands. The colour formation is complete in 30 minutes and the complex is stable for 5 hours at room temperature. The complex is formed in 3.2 to 4.4 M HCl medium and is extracted into acetophenone, giving an absorbance maximum at 435 nm. The method affords a greater sensitivity than the well-known thiocyanate-stannous chloride method. Many commonly associated ions do not interfere; while interferences from Mo(VI), W(VI), V(V) and Se(IV) can be eliminated by a chloroform-tertiary amine extraction prior to the determination of rhenium.