Extraction Of Niobium Research Articles

Influence of zirconium on the extraction of niobium from nitric acid by phosphate esters

Using stable niobium solutions in nitric acid, the extraction of tracer niobium into di-n-butyl butyl phosphonate has been studied over the 2–9M HNO3 range in the prescence of varying concentrations of zirconium up to 0.4 M. The large synergic effect on niobium extraction produced by the presence of macro zirconium has been studied in detail using 8 M HNO3, and the formation of double zirconium/niobium complexes is suggested. Similar but less marked synergic effects in the extraction of niobium into tri-n-butyl phosphate in the presence of zirconium are also reported.

The extraction of niobium (V) and Tantalum (V) by Octylarsinic acid in chloroform

Dioctylarsinic acid (HDOAA) in chloroform solution extracts Nb(V) and Ta(V) efficiently from solutions containing oxalate and oxalic acid at hydrochloric acid concentrations greater than 1 M.The extraction coefficients are 92.5 at 7 M hydrochloric acid and 251 at 6 M hydrochloric acid for niobium and tantalum, respectively. These metals can be extracted even more efficiently from sulfuric acid solutions. The results of the reagent- and pH-dependence studies suggested that a trimeric, monobasic oxoacid of niobium, associated with ten HDOAA molecules, is extracted. Tantalum appears to be present in the organic phase as (H 2DOAA) + [Ta(C 2O 4) 3 (HDOAA n] (n=l or 2).

Extraction of trace amounts of niobium(V) by amine oxides and its separation from tantalum(V) and zirconium(IV)

The use of 4-(5-nonyl)pyridine oxide and trioctylamine oxide for the extraction of niobium(V) from different mineral acid solutions is described. The influence of the concentration of the solvents, acids and salting-out agents is discussed. Separations of niobium(V) from tantalum(V) and zirconium(IV) have been achieved.

Solvent extraction of niobium-4-(2-pyridylazo)resorcinol complex and spectrophotometric determination of niobium in oxalato solutions

Solvent extraction of niobium in the form of the pyridylazo resorcinol complex was studied. The strongly colored niobium complex which forms at pH 5.5 and contains 4-(2-pyridylazo)resorcinol and oxalate as ligands can be extracted into the chloroform by means of the tetraphenylarsonium and tetraphenylphosphonium chloride, respectively. The mechanism of the extraction is based on the formation of the ion-associated compounds that form between the hydrophobic organic cation and the oxo(oxalato)(pyridylazoresorcinolo)niobate(V) anion. The chloroform phase is more stable than the aqueous solutions of the complex, and it follows Beer's law in a significantly wider concentration range. A method was developed for the spectrophotometric determination of niobium in the organic phase after the chloroform extraction. This method has certain advantages over the niobium determination with 4-(2- pyridylazo)resorcinol in the aqueous oxalate medium. (auth)

Mutual effects of metals in extractions from fluoride solutions with oxygen-containing solvents

The simultaneous extraction of niobium, zirconium and tantalum from hydrofluoric ncid solutions with oxygen-containing solvents has been studied. When solvents of relatively high dielectric constant- tributyl phosphate. methyl isobutyl ketone and cyclohexanone -are used. the extration of micro amounts of niobium and zirconium is suppressed by the presence of macro amounts of tantalum. This suppression of extraction in the presence of tantalum is also evident with solvents of low polarity, such as diethyl and diisopropyl others, but with these solvents, zirconium is co-extracted with niobium. One of the principal causes of these mutual influences of metals is dissociation and association of the compounds extracted in the organic phase. The formation of mixed ion associated in the extract allows co-extraction of one metal with another. Conversely, the dissociation of complex acids in the organic phase causes suppression of extraction of micro elements by the common ion effect.

Solvent extraction of niobium and tantalum: IX. Extraction with di- n-octylamino butanone-(2) and di- n-octylamino acetic acid

The extraction of niobium and tantalum from hydrofluoric and oxalic acid solutions by di- n-octylamino butanone-(2) [DOAB]and by di- n-octylamino acetic acid [DOAA]has been studied, together with its dependence on the ligand and hydrofluoric acid concentrations. The species of niobium and tantalum extracted with DOAB have been isolated and characterized by analysis and i.r. spectra. I.r. spectra of the ligands as well as of the extracted species dissolved in the organic phase, were compared with the spectra of the separate substances. The complexes (DOABH) 3(MeO(C 2O 4) 3), (Me = Nb, Ta) have been isolated from oxalic acid solutions. From 0.04 M HF solutions, the species isolated correspond to the formulae (DOABH) 2 · NbOF 5 and (DOABH) · TaOF 4 for niobium and tantalum, respectively. In higher concentrations of hydrofluoric acid the formation of the complexes (DOABH) 2 · NbOF 5 and (DOABH) 2 · TaF 7 can be deduced.

Spectrophotometric study and extraction of niobium(V) complexes with catechol and its derivatives as ion-pairs with quaternary ammonium ions: Application to the separation of niobium from other refractory metal ions

The reactions of niobium(V) with catechol and several substituted derivatives were studied. Optimal conditions for colour development in the niobium(V)-catechol system are: pH 6.7–8.0, and heating at 85° for at least 6 min; the wavelength of maximal absorption is 365 nm, and the molar absorptivity is 1.02·10 4. Catechol derivatives require lower temperatures and develop colours with niobium(V) in neutral or slightly acidic solutions. The best of the derivatives studied were 3-methyl-catechol and 4-chlorocatechol. Extraction of the ion-pairs formed between niobium-(V)-catechol and different quaternary ammonium ions, was studied with representative solvents. Similar studies were made on other refractory metal ions, i.e., Ti(IV), V(V), Mo(VI) and W(VI), under the optimal conditions for the reaction with niobium(V). Separations of binary (1:1) mixtures of niobium(V) with Ti(IV), V(V), Mo(VI) or W(VI) at the 5·10 -5 M level were shown to be possible under the predicted conditions.

Solvent extraction of niobium and tantalum VIII. Extraction with some bidentate phosphorus compounds from sulphate solutions

The extraction of niobium and tantalum from sulphate solutions with bis(di- n-hexylphosphinyl) methane [(C 6H 13) 2OPCH 2PO(C 6H 13) 2), di- n-octyl, 1-oxo-octanephosphonate [C 7H 15COPO(OC 8H 17) 2] and di- n-octyl, 2-oxo-propane-phosphonate [CH 3COCH 2PO(OC 8H 17) 2] has been studied. The ligand/metal and hydrogen/metal ratios have been determined by slope analyses. On the basis of the evidence obtained, the extraction mechanism has been deduced. In the systems investigated at low acidity in the aqueous phase, the presence of the extraction species Me(OH) 4L·HL n ( n = 1 or 2) and Me(OH) 3L 2 (Me = Nb, Ta) in the organic phase has been proposed.

Trennung von Elementen Durch Extraktion mit O,O,S - Tríáthyldithiophosphat

Abstract The solvent extraction of niobium (V), tungsten (VI), titanum (IV) by O,O, S - triethyldithiophosphate and hydrochloric acid has been studied. Tungsten (VI) extracts as a WO2Cl2 (C2H5O)2 P(S) SC2 H5. The separation of molybdennum (VI) from niobium (V) and titanium (IV) is described.

The influence of solvents on the extraction of niobium by high molecular alkylamines from hydrochloric acid solutions

1. The influence of a number of organic solvents (halosubstituted hydrocarbons, aromatic solvents, alcohols, ethers) on the extraction of niobium from hydrochloric acid solutions by high-molecular alkylamines was studied. 2. It was confirmed that acid solvents (chloroform, alcohols) strongly suppress the extraction capacity of amine salts, while basic solvents (esters) increase it. The class of the amine does not have any significant influence on the extraction. 3. A relationship was noted between the increase in the extraction of niobium and the increase in the basicity of esters.

Solvent extraction of niobium and tantalum—VII: Extraction with di- n-octylamino alcohols from oxalic metal solutions

The extraction of niobium and tantalum with di- n-octylamino ethanol (DOAE) and di- n-octylamino propanol (DOAP) was studied from oxalic metal solutions in presence of mineral acids. The amine/metal ratio was determined in the organic phase (chloroform). The same ratio for both metals was observed, varying from 3:1 to 1:1, as dependent upon the composition of the aqueous phase. Extracting species of niobium and tantalum were separated under different conditions, and characterised by analysis and i.r. spectra. The i.r. spectra of the organic phases were examined and compared with the spectra of the separated substances. On the bases of this evidence the mechanism of the oxalato niobate and tantalate extraction with these N-substituted long chain amino alcohols is deduced, and this mechanism proved to be of the ion association type.

The Extraction of Niobium (V) from Hydrochloric acid solutions by tri‐n‐octylamine

AbstractThe partition coefficient of niobium(V) between hydrochloric acid solutions and benzene solutions of tri‐n‐octylamine (TOA) has been investigated under various conditions. A spectrophotometric study has been carried out for both the aqueous and organic phase. Further, the effects of organic solvent and of amine structure on the extraction of niobium have been examined.

Solvent extraction of niobium and tantalum: VI. Extraction with di- n-octylamino alcohols from hydrofluoric acid solutions of the metals

Studies of the extraction of niobium and tantalum from hydrofluoric acid solutions, with di- n-octylamino ethanol (DOAE) and di- n-octylamino propanol (DOAP), in chloroform, have been carried out. The metal/amine ratio was determined in the organic phase by the slope analysis. The extracting species of niobium and tantalum with DOAE were separated from the 0.04, 0.4 and 1 M HF systems, respectively. Different extracting species for niobium and tantalum were obtained, and characterized by analysis and infrared spectra. Species containing NbOF 5 2− and TaOF 4 − anions were separated from 0.04 M HF systems.

Solvent extraction of niobium and tantalum—IV: Extraction species with di-n-octyl-methylene-bis-phosphonic acid

The extracting species formed by niobium and tantalum with di-n-octyl-methylene-bis-phosphinic acid were separated from the organic phase and characterized by analysis and i.r. spectra. A previously proposed extraction mechanism for these metals from oxalic and hydrofluoric solutions was confirmed. Molecular weight studies show that the organophosphonic metal derivatives steadily polymerize in the organic phase. The niobium and tantalum polymers are not of the same type.

Use of organic additives to induce selective liquid-liquid extraction of niobium with thenoyltrifluoroacetone

Use of organic additives to induce selective liquid-liquid extraction of niobium with thenoyltrifluoroacetone

Extraction of Niobium (V) by Tri-n-butyl Phosphate from Strongly Acid Solutions in the Presence of Masking Agents

Extraction of Niobium (V) by Tri-n-butyl Phosphate from Strongly Acid Solutions in the Presence of Masking Agents

Solvent extraction of niobium and tantalum: III. Extraction mechanism in oxalic solutions with longchain tertiary amines

Studies of the extraction of niobium and tantalum oxalato solutions with tri- n-octylamine (TOA), tri- n-decylamine (TDA) and tri- n-dodecylamine (TDDA) in carbon tetrachloride have been carried out. The metal/amine ratio was determined in the organic phase and an identical behaviour was observed for all the three extractants. Further studies were carried out in detail with TOA, and extraction-species were separated under different conditions. The infrared spectra of the organic phases were examined and compared with the spectra of the isolated substances. On the basis of this evidence, the mechanism of extraction of niobium and tantalum oxalato complexes with long-chain tertiary amines, is given.

Solvent extraction of niobium and tantalum—I: Extractioni with di-octyl-methylene-bis-phosphonic acid

The extraction of niobium and tantalum has been studied from oxalic, sulphuric, hydrochloric and hydrofluoric acid solutions, with di-octyl-methylene-bis-phosphonic acid (DOMPA). The results are shown on Figs. 1–5 and Table 1. The metal/ligand ratio was determined in the organic phase and the experiments show that the ratio is not the same for both metals, amounting to 1:2 and 1:1 for niobium and tantalum, respectively. The extraction dependence upon fluoride and oxalate ion concentration was also examined. The extraction mechanism is discussed and the presence of extractable, probably polymeric hydroxo-phosphonic species of niobium and tantalum is deduced from the solvent extraction results.

Separations of protactinium from niobium, tantalum and other elements by solvent extraction using n-benzoyl- n-phenylhydroxylamine

The extraction of niobium, tantalum and protactinium from hydrochloric acid solutions containing fluoride into chloroform solutions of N-benzoyl- N-phenylhydroxylamine has been studied. From such aqueous systems it is possible to separate pairs or all three of these elements efficiently and in a reasonably quantitative manner. In addition, protactinium may be easily separated from zirconium (and presumably also hafnium), aluminium, titanium, manganesc(II), iron(III), rare earths and thorium by extracting it from concentrated hydrochloric acid solutions. The back-extraction of niobium, tantalum and protactinium into aqueous phases of various compositions and additional separations thus revealed are also discussed. Phase distribution measurements and separations have been performed using suitable radioactive isotopes of the elements concerned.

On the Carrier-Free Extraction of Niobium with N-Benzoyl-Phenyl-Hydroxylamine

On the Carrier-Free Extraction of Niobium with N-Benzoyl-Phenyl-Hydroxylamine