Solvent extraction of hafnium(IV)

^{175, 181}Hafnium(IV) was extracted by HDBP in 2-ethylhexanol from 1–10M solutions of HClO₄, HCl and HNO₃, and 1–8M H₂SO₄. As with low polar organic phase diluents, the acidity dependence of the distribution ratio of Hf, D, passes through a minimum for HClO₄, HCl, and H₂SO₄ whereas only an increase of D can be observed with increasing HNO₃ concentration. From the slope analysis the following complexes were found to be extracted (HDBP=HA): HfA₄ at <4M HClO₄ and <5M HCl, lg K_extr=9, HfX₄(HA)₄ (X=ClO ₄ ⁻ , Cl⁻ or NO ₃ ⁻ ) at >5M HClO₄, >7M HCl and 1–10M HNO₃, Hf(SO₄)A₂(HA)_3–4 at <3M H₂SO₄, and Hf(SO₄)₂ (HA)₄ at >6M H₂SO₄. Coextraction of sulphate with hafnium from H₂SO₄ solutions was evidenced in experiments with macro concentrations of Hf(IV) and³⁵SO ₄ ²⁻ . Part XX: Coll. Czech. Chem. Commun., 40 (1975) 3617.     

Solvent extraction of hafnium(IV) by TBP and topo from acidic organic-aqueous solutions

Tracer concentrations of Hf(IV) were extracted by 60% TBP solution in benzene from 5M HClO₄, 5M HCl, 6M HNO₃ and 8M H₂SO₄ solutions, and by 1·10^?4 M TOPO solution in benzene from 2M HClO₄ and 2M HCl solutions in the presence of a variety of organic solvents miscible with the aqueous phase. Whereas for TBP these solvents caused an increase of HF(IV) extraction, an opposite effect was observed for TOPO. The results were discussed from the point of view of various solute-solvent and solvent-solvent interactions.     

Solvent extraction of trivalent lanthanide Pr(III), Ho(III) and Er(III) with N-benzoyl-N-phenylhydroxylamine

Extraction of Pr(III), Ho(III) and Er(III) has been studied in the pH range of 1–10 with N-benzoyl-N-phenylhydroxylamine (BPHA) in benzene. The separation was found to be quantitative in borate media from pH 7 to 10, at an ionic strength of 0.1M (H⁺, BO₃ ^3–). The stoichiometric composition of the complexes under the optimal conditions of shaking time, pH and reagent concentration was formulated using slope analysis and found to be M(BPHA)₃, where M=Pr(III), Ho(III) and Er(III). The effect of various masking agents shows that citrate, ascorbate, EDTA, oxalate, fluoride and phosphate form stable complexes with these rare earths as compared to BPHA. The decontamination factors for different cations with respect to these rare earths under the optimum conditions have been evaluated.     

Solvent extraction of thorium (IV) with dialkyldithiophosphoric acids

Solvent extraction of thorium (IV) from aqueous solution with dialkyldithiophosphoric acids (RO)₂P(S)SH, (abbreviated Hdtp) in different organic solvents shows that the chain length in Hdtp significantly influence the magnitude of the distribution ratio. The diluent effect and the influence of the inorganic anion present in the aqueous phase was investigated in the Th — di (2-ethyl-hexyl) dithiophosphoric acid (HEhdtp) extraction system. The treatment of the partition data shows that the extraction of Th(IV) in benzene, cyclohexane, chloroform, carbon tetrachloride and n-butanol from perchlorate, chloride and nitrate media occurs via an ion-exchange mechanism. Inorganic anions present in the aqueous phase do not participate in the formation of the extracted species but influence the magnitude of the distribution ratios.     

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.     

Solvent extraction of Np(IV) and Pu(IV) with mixtures of TOPO and HTTA

Solutions of HTTA are known to extract tetravalent actinides as M(TTA)₄ species. When TOPO is added to HTTA solutions, the extracting of Np(IV) and Pu(IV) from aqueous perchloric acid was enhanced enormously. The species responsible for the enhanced extraction were identified from the extraction data by the slope ratio method and JOB's method. It was found that the predominant species responsible for enhancement in the extraction, when [HTTA]≫[TOPO], was M(TTA)₄. TOPO for both Np(IV) and Pu(IV). Furthermore, it was established that depending on the relative concentrations of HTTA and TOPO, a number of species with the composition M(TTA)_a(ClO₄)_4-a·b TOPO, with a ranging from 1 to 4 and b having values of 1 or 2, are involved in the extraction. Several equilibrium constant values are given. Fuel Reprocessing Division.     

Solvent extraction of Os(IV) with 2-mercaptobenzothiazole into chloroform

2-mercaptobenzothiazole has been used for the solvent extraction of Os(IV) in acidic medium. The extraction of Os(IV) was found to be better than 90% over the pH range of 3.0 to 5.0 with an equilibration time of 5.0 minutes. The stoichiometry of metal:reagent determined by substoichiometric extraction and slope ratio method was found to be 1∶4. Decontamination factor for various elements in the substoichiometric extraction of Os(IV) were also evaluated.     

Solvent extraction of thorium(IV) using W/O microemulsion

The extraction of thorium(IV) was investigated using two types of W/O microemulsion,one of which was formed by a surface-active saponified extractant sodium bis(2-ethylhexyl) phosphate(NaDEHP) and the other was formed by a mixture of an anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate(AOT) and an extractant bis(2-ethylhexyl)phosphoric acid(HDEHP) as the cosurfactant.The extraction capacities of the above two systems were higher than that of the HDEHP extraction system.High concentration of NaNO 3 showed no influence on the extraction in the NaDEHP based W/O microemulsion system,whilst reduced the extractability in the AOT-HDEHP W/O microemulsion system.The mechanism in acidic condition was demonstrated by the log-log plot method.The structure of the aggregations and the water content in the organic phase after extraction were measured by dynamic light scattering and Karl Fischer water titration,respectively.It was found that NaDEHP based W/O microemulsion broke up after extraction,while AOT-HDEHP W/O microemulsion was reserved.     

On the stabilization of niobium(V) solutions by zirconium(IV) and hafnium(IV)

Niobium cannot be separated from zirconium or hafnium when these elements occur together in solution with common anions such as chloride and sulphate. This is ascribed to the co-polymerization of niobium(V) and the hydrolysed ionic species of zirconium(IV) and hafnium(IV) to form colloidal particles. In hydrochloric acid the particles are positively charged, whereas in sulphate solution the Zr-and Hf-sulphate complexes confer a negative charge. The two cases are considered separately.     

Solvent extraction of neptunium(IV) from nitric acid solutions by sulphoxides and their mixtures

Studies have been performed on the liquid-liquid extraction of neptunium from nitric acid solutions by di-n-hexylsulphoxide (DHSO) di-no-octylsulphoxide (DOSO) and di-iso-amylsulphoxide (DISO) and their mixtures over a wide range of conditions. At a given strength of the extractant, extraction of Np(IV) increases initially rapidly with increase in the acid concentration; at high acidities, above 8M HNO₃, the extraction decreases. Under otherwise identical conditions, extraction increases with an increase in the extractant concentration. The species extracted would appear to be Np(NO₃)₄·2(R₂SO). A mixture of two extractants extracts more than the sum of the extractions due to the individual components at concentrations corresponding to those of the mixture. After loading the organic phase with uranium(VI), extractability of Np(IV) becomes considerably lower. The diminution in extraction with increase in temperature is small. A comparison of the extraction behaviour of Np(IV) with those of Pu(IV), U(VI) and some associated fission products has been made.     

Solvent extraction behavior of hexachlorotechnetate(IV) ion in the HCl-TBP system

The solvent extraction behavior of [TcCl₆]²⁻ in the HCl-TBP system was studied together with that of its aqua complexes. It was deduced from the dependence of the distribution coefficient of [TcCl₆]²⁻ both on the HCl and TBP concentrations that a possible form extracted into TBP is H₂[TcCl₆](TBP)₄. The distribution coefficients of aqua complexes of [TcCl₆]²⁻ were found to be in the order of [TcCl₄(H₂O)₂]<[TcCl₆]²⁻<[TcCl₅(H₂O)]⁻.     

Multivariate spectrofluorimetry of ultra trace zirconium(IV) and hafnium(IV) assisted by several chemometrics methods

In the presence of sodium lauryl sulfate (SLS), an anionic surfactant, highly sensitive molecular fluorescence reactions occur between Zr(IV), Hf(IV) ions and quercetin (3, 3', 4', 5, 7-pentahydroxyflavone) in acidic medium to form stable ternary micellar ion-association complexes. Their lambda(ex(max))/lambda(em(max)) values are 435.0/497.9 and 435.0/492.0 nm, respectively, indicating their heavily overlapping fluorescence excitation and emission spectra. The linear ranges of their regression calibration curves are 0 to 0.20 and 0 to 0.12 mg l(-1), respectively, with 0.5 ng ml(-1) for all of sensitivities. The multivariate spectrofluorimetry of ultra trace or trace Zr(IV) and Hf(IV) without separation was performed using a partial least squares (PLS) algorithm and other algorithms. The optimum PLS computation conditions are wavelength point number of 21 and corresponding wavelength range from 450 to 540 nm oriented from lambda(em) 495 nm to two sides at combined intervals of 2.5 and 5.0 nm at a fixed lambda(ex)of 435.0 nm with an optimum calibration sample number of 12, and respective optimum abstracted factor numbers of 4 and 5. It was concluded that accuracy and precision of the determination results obtained for simulation and real soil samples were poor for LP-M, LP-P, OLS-P, KF-P, and TFA-P algorithms, moderate for OLS-M, KF-M, and TFA-M algorithms, and good for PLS algorithm.     

Solvent extraction of tellurium (IV) with mesityl oxide. Direct nephelometric determination

Summary A fast and selective method has been developed for the extraction of tellurium(IV) with mesityl oxide. Tellurium(IV) is quantitatively extracted by pure mesityl oxide from 2.5–3M hydrochloric acid solutions. After stripping with water, it is determined nephelometrically as the bluish sol. The extracted species probably has the composition TeCl₄ · 2MeO. The optimum period of equilibration is 30 seconds. Tellurium can be extracted and determined in the presence of a large excess of selenium, silver, bismuth, lead, copper and nickel which are associated with it in minerals.

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Zusammenfassung Ein schnelles und selektives Verfahren zur Extraktion von Tellur(IV) mit Mesityloxid wurde ausgearbeitet. Aus 2,5- bis 3-m Salzsäure gelingt diese Extraktion quantitativ. Nach Waschen mit Wasser wird das bläuliche Sol nephelometriert. Die extrahierte Substanz hat vermutlich die Zusammensetzung TeCl₄ · 2MeO. Die Gleichgewichtseinstellung erfolgt in 30 sec. Tellur kann so in Gegenwart eines großen Überschusses von Se, Ag, Bi, Pb, Cu und Ni bestimmt werden, mit denen es in Mineralen vergesellschaftet ist.

     

Solvent extraction of Hf(IV) and Zr(IV) with some 1-phenyl-3-methyl-4-acylpyrazolones-5

The distribution of Hf, Zr and Nb between aqueous solutions of mineral acids and solutions of 1-phenyl-3-methyl-4-acylpyrazolones-5 (acyl=acetyl, ethoxycarbonyl, butyryl, capronyl, capryl and benzoyl) in various organic solvents has been studied. The dependence of the distribution ratio of metal on the acidity of the aqueous phase, the analytical concentrations of reagents and metals, and on the organic solvent was investigated. The composition of the complex extracted is MeP₄ for Hf and Zr. The conditions for the separation of Zr, Hf and Nb are defined, and a comparison is made with extractions by means of thenoyltrifluoroacetone.     

Solvent extraction of thorium(IV) with dibutyldithiophosphoric acid in various organic solvents

The extraction of thorium(IV) from perchlorate solutions with di-n-butyldithiophosphoric acid (HBudtp) in various organic solvents occurs through an ion exchange mechanism. The extracted species in the organic phase is an eight-coordinate complex Th(Budtp)₄. The higher values of the distribution ratio obtained in HBudtp-benzene-water system than in HBudtp-n-butanol-water system are explained by higher solubility of the complex species in nonpolar solvents. The position of the extraction curves in the pH-range lower than 0.7 reduces the complexation of thorium(IV) with Budtp^– in the aqueous phase and also the hydrolysis process.     

Isolation of dithiocarbazate salts as oxinato-complexes of titanium(IV), zirconium(IV) and hafnium(IV)

Summary Ionic chelate complexes of the type, [(⁵-R)₂ML][dtz] [R=cyclopentadienyl (Cp) or indenyl (C₉H₇); M=Ti^IV, Zr^IV or Hf^IV; HL=oxine; dtz=phenyldithiocarbazate (PhNHNHCS₂)] have been synthesised and characterised. Conductance measurements indicate that the complexes are 11 electrolytes. From i.r. and u.v. spectral studies we conclude that the oxinato-group is chelating. Consequently there is tetrahedral coordination around the metal ion.¹H and¹³C N.m.r. studies are consistent with the stoichiometries. X-ray powder diffraction studies have been made for [(⁵-Cp)₂ZrL][dtz]. For [(⁵-Cp)₂TiL][dtz] and [(⁵-Cp)₂ZrL][dtz] thermal (t.g. and d.t.a.) and mass spectral studies have been carried out.