Studies on extraction of zirconium by quaternary ammonium halides from hydrochloric acid media and its separation from hafnium

The distribution of Zr(IV) between hydrochloric acid media and Hyamine 1622 in the organic phase is described. The dependence of extraction on acidity, extractant concentration and type of diluent, was investigated. The possible extraction mechanism is discussed in the light of the results obtained. A method for the separation and determination of Zr(IV) in a mixture of Zr and Hf is outlined.     

Solvent extraction separation of tantalum from niobium on macro scale using di(2-ethylhexyl) phosphoric acid as extractant

A solvent extraction procedure for the separation of niobium and tantalum has been developed. The method consists of extracting tantalum from its aqueous mixture with niobium, with the help of di(2-ethylhexyl)phosphoric acid (HDEHP) in n-heptane. The aqueous feed consists of niobium and tantalum in an aqueous medium containing hydrochloric and oxalic acids. The concentrations of niobium and tantalum were raised to 1 mg/ml in the aqueous solution. The extraction efficiency of tantalum under these conditions was found to be 85%. Effects of chloride and oxalate ions as well as those of the concentration of HDEHP on the extraction efficiency were studied and discussed in detail.     

Extraction of zirconium and hafnium from hydrochloric acid solutions with derivatives of diantipyrylmethane

Zirconium and hafnium are extracted quantitatively into chloroform, dichloroethane or nitrobenzene in the presence of hexyl-, nonyl- and o-nitrophenyl diantipyrylmethane from hydrochloric acid solutions ( 8 M) in the form of RMeCl₄ ,complexes. New methods of determining up to 1·10⁻⁴% zirconium in materials containing Mg, Be, Al, Y, Sc, La, Ce, Ti, Th, Cr, Ni, and other elements are suggested.     

3-Thianaphthenoyltrifluoroacetone: A new reagent for the solvent extraction of zirconium and hafnium

Summary A method for the solvent extraction of mg quantities of zirconium(IV) and hafnium(IV) from 3-molar perchloric acid with 3-thianaphthenoyltrifluoroacetone is described. The effects due to acidity, choice of acid, time, heating, solvents and reagent concentration are reported.

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Zusammenfassung Eine Methode zur Losungsmittelextraktion von mg-Mengen Zr(IV) und Hf(IV) aus 3-m Perchlorsäure mit 3-Thianaphthenoyltrifluoraceton wurde beschrieben. Der Einfluß der Acidität, der Art der Säure, der Zeit, des Erhitzens, der Lösungsmittel und der Reagenskonzentration wurde erörtert.

     

Selective separation and reversed phase extraction of zirconium and hafnium from a multitracer solution

The solvent extraction of Zr and Hf was studied using 444-trifluoro-1-(2-thienyl)-1,3-butanedione (TTA) from a multitracer solution containing carrier-free radioisotopes of Zr, Hf, and other elements. The multitracer was prepared from Au foil irradiated with high-energy heavy-ion beams. Effects of HCl and HNO₃ concentrations and organic solvent on the extraction and coextraction of other radionuclides have been studied. It was found that decalin (decahydronaphthalene) was the best solvent among 14 solvents studied and the optimum aqueous phase was 2 mol·dm^–3 HCl or HNO₃. About 2–10% of Sr, Rb, Sc and Nb were coextracted with Zr and Hf. The reversed phase extraction of Zr and Hf was also developed by using ethylenediaminetetraacetic acid (EDTA) solution at pH range of 8.5–10.     

N,N,N',N'-Tetrabutyladipicamide as a new extractant in toluene of nitric acid and uranium (VI)

N,N,N',N'-Tetrabutyladipicamide (TBAA) was used for the extraction of nitric acid and uranyl(II) ion from nitric acid media into toluene. The effects of nitric acid, uranyl(II) ion, and extractant concentration, temperature and back extraction on the distribution coefficient of uranyl(II) ion have been studied. The main adduct of TBAA and HNO₃ is TBAA·HNO₃ in 1.0 mol/l nitric acid solution. The 1:2:2 complex of uranyl(II) ion, nitrate ion and TBAA as extracted species is further confirmed by IR spectra of the extraction of uranyl(II) ion with TBAA. The values of the thermodynamic parameters have also been calculated.     

Liquid/liquid extraction separation of hafnium with amberlite La-1 from zirconium and other elements in citric acid solutions

Hafnium (10–110 μg ml^?1) is quantitatively extracted at pH 4.5 from 0.01 M citric acid with 0.1 M Amberlite LA-1 in xylene; it can be stripped with 0.1 M perchloric acid and determined spectrophotometrically with xylenol orange at 540 nm. Hafnium can be separated from binary and multicomponent mixtures by selective extraction and back-extraction. The method is suitable for determining hafnium in zircon.     

Extraction and separation of zirconium from hafnium using a new solvent microextraction technique

A simple method based on the dispersive liquid?Cliquid microextraction and a solidification of floating organic drop followed by an inductively coupled plasma-optical emission spectrometry (ICP-OES) was developed for the extraction and separation of zirconium from hafnium. In this extraction method, an appropriate mixture of acetone (disperser solvent) and 1-undecanol (extraction solvent) was injected rapidly, into the sample solution containing 2.0?mol?L^?1 nitric acid and metal ions in their complex form with cyanex272 and a cloudy solution was formed. After centrifugation, the test tube was cooled by inserting it into an ice bath for 5?min. The solidified 1-undecanol on the top of the solution was transferred into suitable vial and immediately melted, then, 100.0???L of it was dissolved in 100.0???L of 1-propanol and finally, was injected into an ICP-OES by a flow injection system for analysis. Some effective parameters on the extraction and separation of zirconium and hafnium such as type of extraction and disperser solvents and their volumes, type and concentration of ligands, and the type and concentration of acids have been evaluated and optimized. Under the optimum conditions, the selectivity factor of about 13 was obtained.     

Studies on extraction of zirconium(IV) by tricapryl methyl ammonium chloride from sulphate media and its separation from hafnium(IV)

The distribution of Zr(IV) between aqueous H₂SO₄ solutions and organic phases of tricapryl methyl ammonium chloride has been described. The dependence of extraction on acidity, metal and solvent concentration, diluent type and temperature was thoroughly investigated. The possible extraction mechanism is discussed in the light of results obtained. A method for the separation of Hf(IV) from Zr(IV) is also suggested.     

Concentration, separation and determination of scandium, zirconium, hafnium and thorium with a silica-based sulphonic acid cation-exchanger

A study has been made of the dependence of the sorption of scandium, zirconium, hafnium and thorium from aqueous solutions with a silica-based sulphonic cation-exchanger (SCE-SiO(2)) on the concentration and nature of the acid medium, time of contact, concentration of the element, and the ionic strength. The selectivity decreases in the order Zr approximately Hf > Th > Sc > Fe(III). The sorption characteristics of silica gel and SCE-SiO(2) have been compared, and the sorption mechanism is discussed. The SCE-SiO(2) exchanger has been used for 100-fold concentration of scandium, zirconium, hafnium and thorium from their 10(-8)-10(-7) M solutions, and a spectrophotometric method has been developed for their determination with a detection limit of 0.5 ng/ml for Zr and Sc and 0.1 ng/ml for Hf and Th. Zirconium and hafnium have been determined in the solvent phase by X-ray fluorescence and atomic-emission methods.     

Solvent extraction of zirconium from hydrochloric acid solutions by sulphoxides and their mixtures

The solvent extraction of zirconium from HCl solutions by dipentyl sulphoxide (DPSO), dioctyl sulphoxide (DOSO), tributyl phosphate (TBP), and their mixtures in various solvents has been studied. At a given H⁺ strength, the extraction coefficient η of the metal increases with an increase in Cl⁻ activity whereas it is almost independent of H⁺ at constant Cl⁻. Under otherwise identical conditions, η increases with an increase in the extractant concentration but is virtually independent of the metal ion concentration over a wide range. The species extracted are ZrCl₄·DPSO, ZrCl₄·DOSO, and ZrCl₄·2TBP. In the case of mixtures, the slope of the log η−log M extractant plot for one component decreases with an increase in the concentration of the second component, the lines crossing at a common point. Extraction is favoured by solvents of low dielectric constant. It is possible to separate zirconium from thorium and uranium by solvent extraction with sulphoxides.     

Solvent extraction separation of rhodium(III) with N-n-octylaniline as an extractant

Solvent extraction separation method for the determination of rhodium(III) has been described. Selective and quantitative extraction of rhodium(III) by N-n-octylaniline, a high molecular weight amine (HMWA) into xylene takes place from aqueous sodium malonate medium. The effect of concentration of malonate, N-n-octylaniline, role of various diluents, stripping agents and foreign ions on the extraction of rhodium(III) has been studied. The procedure offers distinct improvements in need of real sample analysis and environmental safety as the extraction procedure carried out in weak organic acid media.     

Bis(alkylamido)phenylborane complexes of zirconium,hafnium, and vanadium

The coordination chemistry of the bis(tert-butylamido)phenylborane ligand, [(t)BuN-B(Ph)-N(t)Bu](2)(-), is developed. The ligand can be delivered to metals of groups 4 and 5 from its dilithio salt. The reactions of PhB((t)BuNLi)(2), 1, with metal halides of zirconium, hafnium, and vanadium generate complexes of the general formulas ((t)BuN-B(Ph)-N(t)Bu)(2)M(THF) (M = Zr (2), Hf (3)), Li(2)[M((t)BuN-B(Ph)-N(t)Bu)(3)] (M = Zr (4), Hf (5)), and M((t)BuN-B(Ph)-N(t)Bu)(2) (M = V (6)). (1)H and (11)B[(1)H] NMR and single-crystal X-ray analysis show that these amido metal complexes are structurally analogous to amidinates.     

Reversed phase chromatographic separation of zirconium,niobium and hafnium tracers with HDEHP

Effective separation of the congeneric pair of elements, zirconium and hafnium and also niobium which was in admixtures with zirconium as daughter in its isotopic form were achieved through reversed phase column and paper extraction chromatographic procedures using di-(2-ethylhexyl)phosphoric acid (HDEHP) as the liquid exchanger. In reversed phase column chromatographic separation, the tracers,⁹⁵Zr,⁹⁵Nb and^175,181Hf, were extracted by HDEHP impregnated on kieselguhr and were sequentially eluted with 6N H₂SO₄+xN oxalic acid+H₂O₂(where x=0.1, 0.5 and 2). Similarly, in reversed phase paper chromatographic study in which a coating of HDEHP on Whatman No. 1 chromatographic paper was used as stationary phase, the mobile phase, 18N H₂SO₄+0.1N oxalic acid + H₂O₂, helped in separating the elements with favorable separation factors. Under the optimal conditions, the separation and decontamination of the elements in both methods were found to be quantitative, as verified by -spectrometric studies.     

A novel solid-phase extraction method for separation and preconcentration of zirconium

This work assesses the use of modified natural clinoptilolite as an adsorptive material for separation and preconcentration of trace amounts of zirconium ions. A simple, rapid and economical method was developed for the preconcentration of trace amounts of zirconium in aqueous medium using 1-(2-pyridylazo)-2-naphthol as a complexing agent. Effect of sample pH, flow rate of sample and elution solutions, breakthrough volume and interference of several ions were studied. Determination of zirconium was made by ICP-AES technique. The sorption was quantitative in the pH range from 3.0 to 4.0, whereas quantitative desorption occurred instantaneously with 2 mol L^?1 hydrochloric acid. Linearity was maintained between 0.05 and 9.0 μg mL^?1. Relative standard deviations range from ±0.9% to ±2.3% (n?=?5). The detection limit was 0.1 ng mL^?1. Because of good recovery (>97%), this method is suitable for preconcentration and determination of zirconium in effluents containing trace amount of zirconium.     

Tracer scale solvent extraction separation of tantalum from niobium using di-(2-ethylhexyl)-phosphoric acid as extractant

A simple solvent extraction procedure for the efficient separation of the radioactive tracers⁹⁵Nb and¹⁸²Ta from each other in a mixture using di-(2-ethylhexyl)phosphoric acid (HDEHP) as extractant is described. Tantalum was found to be quantitatively extracted from an aqueous madium, which is 1.6N in HCl and 10^?2 M in oxalic acid, with a HDEHP solution of 0.1 M concentration. Extractabilities of both niobium and tantalum in mineral acids like HCl, H₂SO₄ and HNO₃ and in some organic acids like oxalic, citric, etc., in HDEHP under the experimental conditions were also studied. The reliability of the separation procedure was verified further by γ-ray spectrometry.     

Phenyl-N,N-dibutylcarbamoylmethyl sulfoxide as a new bifunctional extractant for extraction of uranium (VI) in toluene

A new bifunctional extractant named phenyl-N,N-dibutylcarbamoylmethyl sulfoxide (PCMSO) is synthesized and characterized in order to investigate its selectivity and capability in the extraction from acidic nitrate media in nuclear reprocessing. The extraction of uranium (VI) with PCMSO in toluene has been studied at various concentrations of nitric acid, extractant and salting-out agent (LiNO₃). The mechanism of extraction is discussed in the light of the results obtained. The extracted species has also been investigated using FT-IR spectrometry. The related thermodynamic functions were calculated. The IR spectral study was also made of the extracted species.     

Separation of molybdenum from tungsten with di(2-ethylhexyl)-phosphoric acid ac extractant

The use of di(2-ethylhexyl)phosphoric acid (HDEHP) as an extractant for the separation of molybdenum from tungsten was examined with the help of molybdenum-99 and tungsten-187 as radiotracers. Effective separation was obtained when the aqueous phase contained phosphoric acid at pH 0.8–2 or pH 3–3.5, depending on the amounts of metal. The method is applicable to both tracer and milligram amounts of molybdenum. The structure of the extracted species was examined by infrared spectroscopy.