Extractable oxo complexes of vanadium(V) with di(2-ethylhexyl) hydrogen phosphate

Extraction of vanadium(V) with di(2-ethylhexyl) hydrogen phosphate from 1.0–8.0 M aqueous sulfuric acid solutions was studied. The optimal conditions for the extraction were found. The composition of the extractable complex was determined, and the reaction equation for the extraction of V(V) was established. The extraction constant was determined.     

Extraction recovery of vanadium(V) from sulfuric acid solutions

The IR and electronic absorption spectra of di-2-ethylhexyl hydrogen phosphate (HDEHP) extracts of vanadium(V) and sulfuric acid and of vanadium(V) solutions in sulfuric acid were studied. The composition of the extractable complex was determined, and the equation of vanadium(V) extraction with HDEHP was suggested. The equilibrium constant of vanadium(V) extraction from concentrated sulfuric acid solutions was found.     

Vanadium(V) extraction from sulfuric acid solutions

We studied vanadium(V) extraction by di-2-ethylhexylphosphoric acid (DEHPA) from 1.0–12.0 M sulfuric acid. Optimal extraction parameters were determined. IR, ⁵¹V NMR, and electronic spectroscopy was used to determine the stoichiometry of the extracted complex and the reaction equation for vanadium(V) extraction by DEHPA. The equilibrium constant of vanadium(V) extraction by DEHPA was determined.     

Vanadium(V) extraction from sulfuric and hydrochloric acid solutions with hydrazides and <Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-dialkylhydrazides of Versatic acids

Conditions of vanadium(V) extraction from sulfuric and hydrochloric acid solutions with kerosene solutions of hydrazides and N’,N’-dimethylhydrazides derived from fractions of Versatic 10 and Versatic 1519 branched higher carboxylic acids were studied. Conditions of vanadium(V) back extraction from organic phase were studied. For diluted acid solutions, ratios were found to be [V(V)]: [reagent] = 1: 1 and 1: 5 for sulfuric acid media and 1: 1 and 1: 8 for hydrochloric acid media.     

Mechanism of Extraction of Vanadium(V) from Sulfuric Acid Solutions with Di-2-ethylhexylphosphoric Acid

IR and electronic absorption spectroscopies were applied to a study of the mechanism of extraction of vanadium(V) with di-2-ethylhexylphosphoric acid from sulfuric acid solutions.     

Kinetic and mechanistic aspects for the tartaric acid oxidation by vanadium(V) in sulfuric acid medium

Tartaric acid oxidation by vanadium(V) in sulfuric acid medium was investigated spectrophotometrically at 760 nm and 30°C by appearance of the vanadium(IV), as vanadyl. The reaction rate was determined under pseudo-first-order conditions with an excess of hydroxyacid over the oxidant concentration. The oxidation showed a first-order dependence with respect to vanadium(V) concentration and fractional orders with respect to tartaric acid and sulfuric acid concentrations, with no control and with constant ionic strength. The reaction rate is enhanced by an increase of ionic strength, and slightly reduced by a decrease of the dielectric constant of the medium. The activation parameters were calculated based on the rate constants determined in the 293 to 313 K interval. The proposed oxidation mechanisms and the derived rate laws are consistent with the experimental rate laws. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 55–61, 1998.     

Vanadium(V) complexes in sulfuric acid solutions

The ionic state of vanadium(V) is studied spectrophotometrically over a wide range of sulfuric acid concentrations from 1.0 to 16.8 mol/l. Existence regions for monomeric and dimeric vanadium(V) complexes are determined. The equilibrium constant of vanadium(V) dimerization in 12 M H₂SO₄ is determined.     

Joint extraction of vanadium(V) and vanadium(IV) with di(2-ethylhexyl) hydrogen phosphate

The organic extracts formed in joint extraction of vanadium(V) and vanadium(IV) with di(2-ethylhexyl) hydrogen phosphate from weakly acidic aqueous solutions were characterized by IR and electronic spectroscopy and chemical analysis.     

催化动力学极谱法测定痕量钒

在硫酸介质中,以酒石酸为活化剂,痕量钒对溴酸钾氧化甲基橙的反应有极强的催化作用,以极谱法监测催化反应过程中甲基橙及其氧化产物浓度的变化,建立了双峰指示催化动力学极谱法制定痕量钒的新方法,方法的线性范围为0.23-3.70μg/L,检出限为0.17μg/L。方法已用于食品及水样中痕量钒的测定。     

Extraction of vanadium(V) from acid solutions with octyl alcohol isomers

Vanadium(V) extraction with octyl alcohol isomers from acid solutions was studied. Two areas are determined, wherein the vanadium(V) extraction in relation to acidity of the aqueous phase is maximal. The opposite effects of temperature on the extraction are found. The mechanism of the vanadium(V) extraction with high molecular weight alcohols from weakly acid solutions was suggested.     

The determination of small amounts of vanadium in the presence of large amounts of uranium

To eliminate the color interference of large amounts of uranium in the determination of vanadium by the Hamner method, the vanadium was separated prior to titration by the extraction of vanadium cupferrate with chloroform. The chloroform extract was evaporated with sulfuric acid and the excess cupferron removed by oxidation with nitric acid and perchloric acid. The vanadium was reduced with ferrous ammonium, sulfate solution, the excess ferrous ion oxidized with ammonium persulfate, and the vanadium (IV) titrated with 0.02 N potassium permanganate. As little as 1.02 mg of vanadium in the presence of 5 g of uranium oxide was determined accurately by this method.     

Citric acid oxidation by vanadium(V) in sulfuric acid medium: Kinetic and mechanistic study

The citric acid oxidation by vanadium(V) in sulfuric acid medium at 303 K is reported. The reaction rate was determined spectrophotometrically by monitoring the formation of vanadium(IV) at 760 nm. The oxidation showed a first‐order dependence with respect to vanadium(V) concentration and fractional order with respect to citric acid concentrations, with no control and with constant ionic strength. The reaction is also first order with respect to sulfuric acid concentration with no control and of fractional order at constant ionic strength. The reaction rate is enhanced by an increase of ionic strength and increased by a decrease of the dielectric constant. The activation parameters were calculated based on the rate constants determined in the 293 to 313 K interval. The proposed oxidation mechanisms and the derived rate laws are consistent with the experimental rate laws. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 566–572, 2000     

Application d'un reactif sulfovanadique en milieu acetique anhydre a l'etude analytique de quelques acides α-carbonyles ou α-hydroxyles

(Application of a vanadium(V) reagent in anhydrous acetic acid to the determination of some α-carbonyl or α-hydroxyl carboxylic acids). The reagent is prepared from vanadium pentoxide and sulfuric acid in anhydrous acetic acid medium. The oxidation kinetics of various α-carbonyl (glyoxylic, pyruvic, phenylglyoxylic) and α-hydroxyl (glycolic, lactic, mandelic, gluconic) acids are described. A study of the reaction stoichiometry shows that the immediate reaction, corresponding to the consumption of 2–9 mol V(V) mol^?1 of acid, depending on the acid, is useful quantitatively, except for lactic acid which gives a slow non-stoichiometric reaction.     

Extraction of Vanadium (IV) with DI-2-Ethylhexylphosphoric Acid

Abstract

It was established with the use of electron and ESR spectroscopic methods that in the presence of sodium sulfate, the extraction of vanadium (IV) with di-2-ethylhexylphosphoric acid takes place by a cation-exchange mechanism giving rise to two complex compounds of vanadium (IV) oxocation with sulfuric and di-2-ethylhexylphosphoric acid anions. The vanadium (IV) oxocation sulfate complex extracted in the solid state was examined with X-ray structural analysis. It was shown that the vanadium (IV) oxocation sulfate complex trihydrate crystallizes in the centrosymmetrical space group to form dimers with bridging sulfate groups.     

动力学分析法研究(Ⅲ)——BKrO3-钒(Ⅴ)-柠檬酸-溴酚蓝体系催化光度法测定痕量钒

钒对许多均相反应都有催化作用,但利用催化光度法测定痕量钒国内研究较少。作者发现钒(Ⅴ)对稀硫酸介质中溴酸钾氧化溴酚蓝褪色的反应有催化作用,通过条件试验,建立了利用这一新指示反应催化光度法测定痕量钒的方法。     

Mechanism of oxidation of cyclohexanehexol (inositol) by quinquevalent vanadium

The oxidation of inositol by quinquevalent vandadium in acid medium is a first-order reaction both in vanadium (V) and inositol. The stoichiometry of the reaction is consistent with the use of two equivalents of vanadium (V) per mole of inositol with the formation of one mole of inosose. The reaction is catalyzed both by sulfuric and perchloric acid, but the rate is faster in sulfuric acid than in perchloric acid. In 1M–6M perchloric acid solutions the reaction has shown a variable order in H⁺, but in solutions of 2M–5M sulfuric and perchloric acid of constant ionic strength, the rate has a linear dependence on [H⁺]². There is also a linear correlation between the rate and bisulfate ions in sulfuric acid at constant hydrogen ion concentration. The energy of activation is found to be 19 kcal/mole and a negative entropy value of ? 14 e.u. A suitable mechanism, consistent with the kinetics in 2M–5M acid solutions, is suggested and the values of various rate constants are evaluated.     

Extraction of vanadium(V) by N′,N′-dialkylhydrazides of carboxylic acids from acidic solutions

Extraction of vanadium(V) with solutions of 2-ethylhexanoic acid N′,N′-dialkylhydrazides in kerosene from acidic media was studied. The optimal extraction conditions were determined depending on the concentrations of H₂SO₂, HCl, and the extraction agent; the composition of the recovered complexes was proposed. The conditions for back-extraction of vanadium(V) from the organic phase were studied. It was found that benzoic acid N′,N′-diheptylhydrazide did not recover vanadium(V) from acidic media.     

Use of N-benzyl-2-naphthohydroxamic acid as a highly selective reagent for solvent extraction and spectrophotometric determination of vanadium(V)

N-Benzyl-2-naphthohydroxamic acid extracts vanadium(V) selectively and quantitatively into chloroform from 2-8.5M hydrochloric acid in the presence of Mo(VI), Zr(IV) and Ce(IV). The extraction takes place quickly and gives a stable reddish-violet extract which shows an absorption maximum at 505 nm with molar absorptivity of (5.34 +/- 0.05) x 10(3) 1.mole(-1).cm(-1). The optimum range for the determination is 2.2-7.4 ppm of vanadium(V) in the final solution. The method has been used for the determination of vanadium in steels.     

Flüssig-Flüssig-Extraktion von Vanadium mit ausgewählten zweizähnigen Chelatbildnern

Liquid-Liquid Extraction of Vanadium with Bidentate Ligands The extraction of vanadium(V) as well as vanadium(IV) with thenoyltrifluoracetone, 1-phenyl-3-methyl-4-benzoylpyrazol-5-one, N-benzoyl-N-phenylhydroxylamine, maltol, di-2-ethylhexylphosphoric acid, and selected 8-quinolinols was studied in comparison with corresponding thioanalogue compounds. In the reaction of vanadium(IV) with 7-methyl-8-quinolinol vanadium(IV) and vanadium(V) compounds were isolated side by side.     

Mixed Ligand Complexes of Vanadium(V): Extraction With Some New Hydroxamic Acids and Application in Steel.,Rock and Environmental Anaysis

Abstract

Five new substitued hydroxamic acids are used for extraction and spectrophotometric determination of vanadium(V) in trace amounts. the binary complex of vanadium (V) with H-p-ciloropheny 1-3,4,5-trimethoxycinnamohdroxamic acid (PTCHA) and the mixed ligand complex of vanadium (V) with N-p-cinlorpheny-p-chlorophenoxyisobutyrohydroxamic acid (PP3HA) and thiocyanete were studied. The molar absorbtivities of the bluish violet vanadium(V) hydroxamate and mixed ligand complexes are 6.9 × 10³ and 1.1 × 10⁴ cm³ mol^?3 cm^?1, respectively. The vanadium is also determined with AAs and the method is applied for its determination in steel. alloy, rock and environmental samples.