Liquid-liquid extraction study of tellurium(IV) with N-n-octylaniline in halide medium and its separation from real samples

N-n-Octylaniline in xylene is used for extractive separation of tellurium(IV) from hydrochloric acid media. Tellurium(IV) is extracted quantitatively with the 3% reagent in xylene from 5.5 to 7.5 M hydrochloric acid. It is stripped from organic phase with 1:1 ammonia and estimated spectrophotometrically with pyrimidine-2-thiol (4'-bromoPTPT). The effects of metal ion, acids, reagent concentration, diluents and various foreign ions have been investigated. The log-log plots of distribution ratio (D(Te(IV))) versus N-n-octylaniline concentration indicate that the nature of extracted species is [(RR'NH(2)(+))(2) TeCl(6)(2-)](org). The method affords binary separation of tellurium(IV) from gold(III), selenium(IV), bismuth(III), copper(II), lead(II), antimony(III), germanium(IV) and is applicable to the analyses of synthetic mixture containing associated metal ions and alloy samples. The method is simple, selective, rapid and accurate.     

Extraction and separation studies of platinum(IV) with N-n-octylaniline

N-n-octylaniline in xylene is used for the extractive separation of platinum(IV) from acidic media. Platinum(IV) was extracted quantitatively with 10 ml of 3% reagent in xylene from 0.5 to 10 and 2.5 to 10 M hydrochloric and sulphuric acid, respectively. It was stripped from organic phase with water and estimated photometrically with stannous chloride. The effect of metal ion, acids, reagent concentration and of various foreign ions has been investigated. The method affords binary separation of platinum(IV) from iron(III), cobalt(II), nickel(II) and copper(II), and is applicable to the analysis of synthetic mixtures and alloys. The method is fast, accurate and precise.     

Liquid anion exchanger study of gold (III) from aqueous halide media with N-n-octylaniline

N-n-octylaniline in xylene is used for the extractive separation of gold(III) from halide media. Gold(III) was extracted quantitatively with 10 ml of 2% reagent in xylene from 0.5-10 M and 0.5-8 M hydrochloric acid and hydrobromic acid, respectively. It was stripped from the organic phase with ammonia buffer solution (pH 10.1) and estimated spectrophotometrically with stannous chloride. The effect of metal ion, acids, reagent concentration and of various foreign ions has been investigated. Method is applicable to the analysis of synthetic mixtures containing platinum metals and alloy samples. The method is fast, accurate and precise.     

Rapid Solvent Extraction of Tin(IV) with High Molecular Weight Amine from Hydrochloric Acid Solution

A novel method has been developed for the solvent extraction of tin(IV) from 8 M hydrochloric acid with 4% N‐n‐octylaniline. Tin(IV) from the organic phase was determined spectrophotometrically with pyrocatechol violet at 550 nm. Extraction was found to be quantitative in the range of 7–10 M hydrochloric acid. When the concentration of N‐n‐octylaniline was varied from 0.05–20% in xylene, it showed that optimum concentration was > 3%. Amongst diluents like benzene and xylene, toluene was found to be an effective diluent. Effect of shaking time, concentration of metal ion, and salting out agents was studied. Tolerance limits of various diverse ions were determined by masking interfering cations. Tin(IV) was separated from associated elements in its binary mixture with Se(IV), Sb(III), Bi(III), Pb(II), Au(III), Cu(II) and Zn(II) and from its ternary mixtures with Sb(III), Bi(III) and Cu(II), Au(III). The proposed method was applied for separation and determination of tin(IV) in tin bearing alloys and foodstuffs.     

Liquid Extraction of Noble Metal Ions with an α-Amino Phosphonate

The extraction of Au(III), Pt(IV), and Pd(II) ions from aqueous hydrochloric acid solutions with solutions of bis(2-ethylhexyl) N-butyl-N-octylaminomethylphosphonate in chloroform and xylene was studied. The recovery of the noble metal ions is the most efficient at low acidities of the aqueous solution, with a high selectivity of separation from the concomitant Fe(III), Cu(II), Ni(II), and Co(II) ions.     

Solvent extraction separation of tin (IV) with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A)

Solvent extraction of tin(IV) from hydrochloric acid media was carried out with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in toluene. Tin(IV) was quantitatively extracted with 2.5x10(-2) M PC-88A in toluene from 0.1-0.3 M HCl when equilibrated for 5 min. Tin(IV) from the organic phase was stripped with 4 M HCl and determined spectrophotometrically by both the morin and pyrocatechol violet method. The nature of the extracted species was determined from the log-log plots. Various other diluents such as xylene, hexane and cyclohexane also gave quantitative extraction of tin. The metal loading capacity of the reagent was found to be 0-15 ppm of tin(IV). The extraction of tin(IV) was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. Tin(IV) was successfully separated from commonly associated metal ions such as antimony(III), bismuth(III), lead(II), thallium(I), copper(II), nickel(II), etc. The method was extended for determination of tin in real samples.     

Spectrophotometric determination of zirconium, uranium, thorium and rare earths with arsenazo III after extractions with thenoyltrifluoroacetone and tri-n-octylamine

A method is described for the spectrophotometric determination of microgram amounts of zirconium, uranium(VI), thorium and rare earths with Arsenazo III after systematic separation by extraction. First zirconium is extracted into a xylene solution of thenoyltrifluoroacetone (TTA) from about 4M hydrochloric acid. Uranium(VI) is then extracted into a xylene solution of tri-n-octy lamine from about 4M hydrochloric acid. Thorium is next extracted into TTA solution at pH about 1.5, and finally rare earths are extracted into TTA solution at pH about 4.7. Each metal is back-extracted from the organic phase before determination.     

Extraction of copper(II) with the APCD/DIBK system from concentrated hydrochloric and nitric acid media: estimation of true limit of acidity for the extraction

The extraction of copper(II) from strongly acidic solution (0.01-8M hydrochloric and 0.01-5M nitric acid) with ammonium 1-pyrrolidinecarbodithioate in di-isobutyl ketone has been studied. Compared with the hydrochloric acid system, a considerably larger amount of the reagent is needed for complete extraction of copper chelate from nitric acid solution as the extract is more unstable in the nitric acid system. The decomposition of copper chelates extracted from nitric acid is based on the oxidation of the reagent and the chelate; the spectral change of the extract from nitric acid suggests that the copper(II) chelate is initially oxidized to copper(II) and then decomposes. The upper limit of the acidity of both acids from which the copper chelate can be quantitatively extracted strongly depends on the reagent concentration; the limit with 8 x 10(-2)M APCD (500-fold reagent: metal molar ratio) was taken as 8 and 4M for hydrochloric and nitric acid, respectively.     

Extraktions-spektrophotometrische Bestimmung von Zinn in Fein- und Hüttenblei

A method suitable for the determination of 0.001–0.2% of tin in lead is described. Quadrivalent tin is extracted from the sample solution (6–8 N in hydrochloric acid) by a solution of Amberlite LA-2 in xylene and back-extracted into the aqueous phase by dilute nitric acid. After evaporation of the acidic extract and destruction of the organic matter tin is determined in the residue by Lukes method with 9-phenylfluorone as reagent.     

Extraction of palladium(II) from hydrochloric acid solutions by (RS)-1-(4-chlorophenyl)-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)-pentan-3-ol

The extraction properties of (RS)-1-(4-chlorophenyl)-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)-pentan-3-ol (with chloroform as a diluent) with respect to palladium(II) were studied. Palladium(II) was found to be efficiently extracted by the reagent from 0.1–6 M HCl solutions by the coordination mechanism. The rate of palladium(II) recovery depends on the hydrochloric acid and chloride ion concentrations in the aqueous phase. Conditions for the selective separation of palladium(II) and copper(II) from nickel(II), cobalt(II), and iron(III) were determined.     

Copper(II) extraction with 1-{[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]-methyl}-1H-1,2,4-triazole from hydrochloric acid solutions

Copper(II) extraction with 1-“[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl]-methyl”-1H-1,2,4-triazole in toluene from hydrochloric acid solutions is studied. It is shown that copper(II) is most efficiently extracted with this reagent from 3–5 M HCl solutions. For aqueous acidity of 3 mol/L HCl, the extraction is an exothermal process and follows the coordination mechanism. The anion-exchange extraction mechanism predominates where HCl concentrations is greater than 6 mol/L. The studied reagent can be used for the selective separation of copper(II) from nickel(II) and cobalt(II) at aqueous acidities of up to 4 mol/L HCl.     

Solvent extraction separation of zirconium from malonate solution with high molecular-weight amines

Zirconium is quantitatively extracted with 4% Amberlite LA-1 or LA-2 in xylene, from 0.01 M malonic acid medium at pH 3.0 and stripped from the organic phase with 2M hydrochloric acid, then determined spectrophotometrically at 665 nm as its complex with Arsenazo III. Zirconium is separated from various other elements by selective extraction and stripping. The method has been applied to the analysis of zircon.     

Evaluation of unsymmetrical dithiodiglycolamide as novel extractant for application in selective separation of palladium(II) from aqueous solutions

A novel unsymmetrical multidentate ligand namely; N,N'-dimetyl-N,N'-didecyldithiodiglycolamide (DMD³TDGA) was synthesized and used as agent for the selective extraction of palladium(II) from hydrochloric acid solutions. A systematic investigation was carried out on the extraction of Pd(II) using DMD³TDGA. The quantitative extraction of Pd(II) with DMD³TDGA in n-dodecane is observed at ~4 M HCl. The main extracted species of Pd(II) is PdC_l2. DMD³TDGA and IR spectra of the extracted species were investigated. The extraction of palladium(II) from various concentrations of hydrochloric acid solutions in the presence of metal ions, such as Pt(IV), Rh(III), Cr(II), Ni(II), Fe(III), Nd(III), Zr(II), and Mn(II) was carried. DMD³TDGA showed very high selectivity and extractability for Pd(II). Quantitative back extraction of Pd(II) was obtained in single contact using thiourea solution. The results obtained indicated that, excellent separation of Pd(II) from the investigated metal ions can be achieved. Five successive cycles of extraction/back-extraction, indicating excellent stability and re-utilization of this new extractant can be used for selective separation of Pd(II) from other elements in hydrochloric acid medium.     

Ion-pair formation of a copper(II)-ammine complex with an anionic surfactant and the recovery of copper(II) from ammonia medium by the surfactant-gel extraction method.

The extraction and separation of copper(II), zinc(II), cobalt(II), and cadmium(II) were investigated. Both copper(II) and zinc(II) formed ammine-complexes, while cadmium(II) and cobalt(II) formed hydroxide precipitates in an ammonia medium. By the addition of sodium dodecylsulfate (SDS), a copper(II) complex formed an ion-pair (copper-ammine-DS), which was extracted into the SDS phase. However, a zinc(II) complex did not form an ion-pair, and was soluble in water. Copper(II) ion was recovered by stripping (back-extraction) after the addition of hydrochloric acid. This method was applied to the separation of copper(II) in a brass alloy.     

Separation of selenium(IV) and tellurium(IV) from mixtures by extraction chromatography with trioctylphosphine oxide

The reversed-phase extraction chromatographic separation of selenium(IV) and tellurium(IV) from several elements with trioctylphosphine oxide as extractant is reported. Selenium was extracted from 6M hydrochloric acid containing 7M lithium chloride was stripped with 4M hydrochloric acid, and tellurium was extracted from either the same medium as selenium or from 4M hydrochloric acid, and stripped with 1-2M hydrochloric acid. Selenium and tellurium can be separated from multicomponent mixtures.     

Palladium(II) Extraction from Hydrochloric Acid Solutions with 4-[(Hexylsulfanyl)methyl]-3,5-Dimethyl-1H-Pyrazole

Palladium(II) extraction from hydrochloric acid solutions with a novel weakly basic complexing reagent, 4-[(hexylsulfanyl)methyl]-3,5-dimethyl-1H-pyrazole, dissolved in chloroform was studied. Palladium(II) was found to be highly efficiently extracted from 0.1–3 mol/L HCl solutions. A coordination mechanism of palladium(II) extraction with a protonated form of the reagent via fast interphase transfer of ion associates was proposed. The composition of the extracted compound, [PdCl₂μ-L]_n (n > 2), was found, and the way of coordination of the reagent to metal ions through N(2) nitrogen atom and thioether sulfur atom was determined. The reagent can be recommended for concentrating palladium(II) and selectively separating it from platinum(IV), copper(II), nickel(II), and iron(III).     

Liquid extraction of noble metal ions with bis(α-aminophosphonates)

Extraction of Au(III), Pt(IV), and Pd(II) ions from hydrochloric acid media with solutions of two bis(aminophosphonates), such as N,N-bis(dipentoxyphosphorylmethyl)octylamine and N,N′-bis[[(dioctyloxyphosphoryl)methyl]butylamine], in chloroform and xylene was investigated. Both these extractants proved to be highly effective for Au(III) ions in a wide acidity range, which allows these ions to be separated from other noble metal ions with a high degree of selectivity. At the same time, Pt(IV) and Pd(II) ions cannot be separated from one another with the extractants studied. The selectivity of their separation from Fe(III), Cu(II), Co(II), and Ni(II) metal ions is, too, not high. The reasons for these results lie in the specific structural features of the extractants, which predetermine the extraction mechanism.     

N-acetylsalicyloyl-N-phenylhydroxylamine as an analytical reagent Determination of niobium and tantalum in the presence of each other

N-Acetylsalicyloyl-N-phenylhydroxylamme is proposed for the separation of niobium(V) and tantalum(V) and their gravimetric determination. Niobium is precipitated at pH 5.5-6.5 by the reagent and the complex is weighed directly. Tantalum is precipitated from 1-2M hydrochloric acid solutions and the complex is ignited to tantalum pentoxide. The method is fairly selective. In the presence of thiocyanate the reagent forms an extractable complex with niobium. The reaction forms the basis of a selective and sensitive spectrophotometric determination of niobium.     

Pyrimidinethiol as a reagent for extraction separation of platinum metals and gold Determination of Pd(II), Os(VIII) and Ru(III)

The solvent extraction separation of Pt(IV), Pd(II), Os(VIII), Ru(III) and Au(III) from one another and also from Rh(III) and Ir(III) with 1-(2'-nitro-4'-tolyl)-4,4,6-trimethyl-(1H, 4H)-2-pyrimidinethiol has been investigated. Photometric procedures have been developed for the determination of Pd(II), Os(VIII) and Ru(III) with the same reagent. The reagent allows the enrichment of Pd(II) and Au(III) at the trace level from a large volume of aqueous medium even in the presence of base metals. The method can be used for the determination of platinum metals and gold in alloys.     

Separation and determination of ruthenium by evolution with chromium(VI)-condensed phosphoric acid reagent

Ruthenium in various chemical forms can be evolved as the tetroxide from insoluble matrix materials by heating the sample with chromium(VI)-condensed phosphoric acid reagent (abbreviated as Cr(VI)-CPA). Because of its excellent decomposing power for various solid samples, condensed phosphoric acid is very useful in the chemical analysis of various insoluble materials, and when an oxidizing agent such as potassium dichromate is added in the CPA medium, drastic oxidation proceeds on heating. This method is now extended to the separation of ruthenium from marine sediments. During the reaction with Cr(VI)-CPA ruthenium tetroxide is evolved and collected in an absorbent solution of 6M hydrochloric acid and ethanol (1:1), and the ruthenium is then determined spectrophotometrically with thiourea or radiometrically by counting the beta or gamma-activity. Osmium, which can be evolved as the tetroxide by the same treatment, can be eliminated beforehand by heating the sample with Ce(IV)-CPA, which removes osmium but not ruthenium. The successive distillations by means of Ce(IV)-CPA and Cr(VI)-CPA give satisfactory results for the separation between osmium and ruthenium. This method might be useful for the separation of ruthenium in geochemical or neutron-activation analysis.