Improved separation of iron from copper and other elements by anion-exchange chromatography on a 4% cross-linked resin with high concentrations of hydrochloric acid

Iron(III) can be separated from copper(II) and many other elements by eluting these from a column of AG1-X4 anion-exchange resin with 8M hydrochloric acid, while iron(III) is retained and can be eluted with 0.1M hydrochloric acid. The separation is much better than the customary one with 3.5M hydrochloric acid. Columns containing only 8.8 ml (3 g) of resin can separate traces or up to more than 1 mmole of iron(III) from more than 1 g of copper. Mn(II), Ni, Al, Mg and Ca are quantitatively eluted together with copper(II). Lead, the alkali metals, Be, Sr, Ba, Ra, Sc, Y and the lanthanides, Ti(IV), Zr, Hf, Th and Cr(III) have not been investigated in detail but should be separated according to their known distribution coefficients. Separations are sharp and quantitative, less than 1 mug of copper remaining in the iron fraction when more than 1 g was present originally. Relevant elution curves and results of the quantitative analysis of synthetic mixtures are presented.     

Preparation and properties of a new chelating resin containing 1-nitroso-2-naphthol as the functional group

A macroreticular polystyrene-based chelating ion-exchanger containing 1-nitroso-2-naphthol as the functional group has been synthesized. The exchange-capacity of the resin for a number of metal ions such as copper(II), iron(III), cobalt(II), nickel(II), palladium(II) and uranium(VI) as a function of pH has been determined. The sorption and elution characteristics for palladium(II) and uranium(VI) have been thoroughly examined with a view to utilizing the resin for separation and concentration of uranium and palladium. Uranium(VI) has been separated from a mixture of ten other metal ions by sorption on the chelating resin and selective elution with 0.5M sodium carbonate. Palladium(II) has been separated from various metal ions by selective sorption on the resin in 1M hydrochloric acid medium.     

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.     

Improved separation of cadmium-109 from silver cyclotron targets by anion-exchange chromatography in nitric acid—hydrobromic acid mixtures

A method is presented for improved separation of ¹⁰⁹Cd from silver cyclotron targets. After dissolution of the target material in nitric acid and removal of silver by precipitation with copper metal, at pH 5, the cadmium is separated from zinc, copper and other elements by anion exchange chromatography. The solution in 0.5 M nitric acid plus 0.1 M hydrobromic acid is percolated through a column containing 4 ml of AG1-X8 anion-exchange resin (100–200 mesh), equilibrated with the same acid mixture. Zinc, copper(II) and other elements are eluted with 50 ml of this mixture. Cadmium is retained and finally eluted with 50 ml of 3 M nitric acid. The cadmium is retained much more strongly from the hydrobromic acid mixture than from the 0.02 M hydrochloric acid used for such separations previously; the presence of the strongly absorbed nitrate anion in fairly high concentration completely eliminates the tailing of zinc observed in 0.02 M hydrochloric acid. A typical elution curve and results of quantitative separations are presented.     

A selective lon-exchange separation and spectrophotometric determination of traces of copper in silicate rocks

Summary A combined cation-exchange separation-spectrophotometric procedure has been worked out for the accurate determination of traces of copper in silicate rocks. Silicates are opened up with sulfuric and hydrofluoric acids. The residue is taken up into a 0.5 M hydrochloric acid −0.05 M oxalic acid −1% hydrogen peroxide solution and loaded on a strongly acidic cation-exchange resin column. Polyvalent ions including ferric ions do not adsorb on the column, while copper (II) retains together with divalent metal ions as well as aluminum (III). Copper (II) can selectively be eluted by a small volume of 0.05 M thiosulfate solution. This fraction is sufficiently pure to allow a direct spectrophotometric determination of copper with Na-DDTC without the addition of tartrate and EDTA as masking agents. Quantitative results are quoted for the determination of copper in international standard rocks of the Geological Survey of Japan (GSJ) and the U.S. Geological Survey (USGS).     

Preparation and properties of a chelating resin containing the nitrosoresorcinol group

A macroreticular polystyrene-based chelating resin with the nitrosoresorcinol group as the functional group has been synthesized. The resin shows selectivity for copper(II), iron(III), and cobalt(II). The sorption behaviour of cobalt(II) is examined in detail, with the intention of using the resin analytically. Iron(III) and cobalt(II) are separated in a column operation by stepwise elution with oxalic acid solution and hydrochloric acid respectively.     

The retention behavior of radionuclides on copper(ii)sulfide

The adsorption properties of copper(II) sulfide in various acid solutions for different radiotracers are described. Column and batch equilibration methods are discussed. Copper(II) is selectively adsorbed on CuS; the decontamination factor exceeds 10⁶ for column operations in 6 M hydrochloric acid solution. Among the 30 ions tested in 6 M hydrochloric acid, only copper and gold are adsorbed quantitatively; mercury, silver, bromine, technetium and molybdenum are adsorbed partially. The retention capacity for copper(II) is around 20 mg Cu/g CuS. The adsorption processes on CuS as functions of acid concentrations (HCl, HClO₄ and H₂SO₄) are described. The method seems applicable in activation analysis for trace elements in copper matrices.     

Sorption behaviour of lanthanum(III), neodymium(III), terbium(III), thorium(IV) and uranium(VI) on Amberlite XAD-4 resin functionalized with bicine ligands

The complexing properties (capacity, pH effect, breakthrough curve) of a chelating resin, containing bicine ligands, were investigated for La(III), Nd(III), Tb(III), Th(IV) and U(VI). Trace amounts of these metal ions were quantitatively retained on the resin and recovered by eluting with 1 M hydrochloric acid. The capacity of the resin for La(III), Nd(III), Tb(III), Th(IV) and U(VI) was found to be 0.35, 0.40, 0.42, 0.25 and 0.38 mmol g(-1), respectively. Separation of U(VI) and Th(IV) from Ni(II), Zn(II), Co(II) and Cu(II) in a synthetic solution was carried out.     

Adsorption of chloro-complexes of the first row transition elements by Dowex A-1

A study has been made of the adsorption of chlorocomplexes of the first row transition metals by the chelating resin Dowex A-1, and possible mechanisms for adsorption have been reviewed. Relative adsorption follows the series Zn(II) > Co(II) = Fe(III) Cu(II) > Mn(II). Negligible adsorption occurred with Cr(III) and none with V(IV) and Ni(II). Maximum adsorption of Zn(II) occurred from 3M hydrochloric acid and for the other metals from 8M acid.     

Chemical analysis of manganese nodules : Part II. Determination of uranium and thorium after anion-exchange separation

A method is described for the determination of uranium and thorium in manganese nodules. After dissolution of the sample in a mixture of perchloric and hydrofluoric acids, uranium is adsorbed on the strongly basic anion-exchange resin Dowex 1 (chloride form) from 6 M hydrochloric acid. The effluent is evaporated and the residue is taken up in 7 M nitric acid—0.25 M oxalic acid; thorium is then isolated quantitatively by anion-exchange on Dowex 1 (nitrate form). Thorium is eluted with 6 M hydrochloric acid and determined spectrophotometrically by the arsenazo III method. Uranium is eluted from the resin in the chloride form with 1 M hydrochloric acid and then separated from iron, molybdenum and other co-eluted elements on a column of Dowex 1 (chloride form); the medium consists of 50% (v/v) tetrahydrofuran, 40% (v/v) methyl glycol and 10% (vv) 6 M hydrochloric acid. After removal of iron and molybdenum by washing the resin with a mixture of the same composition and with pure aqueous 1 M hydrochloric acid, the adsorbed uranium is eluted with 1 M hydrochloric acid and determined by fluorimetry. The method was used successfully for the determination of ppm-quantities of uranium and thorium in 60 samples of manganese nodules from the Pacific Ocean.     

Effect of acidity on the extraction and kinetic stability of the copper(II)/APCD/IBMK system in strongly acidic media

The extraction of copper(II) from strongly acidic solution (0.01-8M hydrochloric acid) with ammonium 1-pyrrolidinecarbodithioate in isobutyl methyl ketone has been investigated. The shaking time needed for quantitative extraction decreases as the acidity is increased. The effect of the mutual solubility of the organic solvent and the aqueous phase is significant when the acidity of the aqueous phase is increased. The acidity of the aqueous phase mainly affects the kinetic stability of the chelate during the shaking period, rather than the decomposition of the chelating agent. The kinetic stability of the chelate apparently depends on the mole ratio of reagent to copper, the half-lives for the chelate extracted from 4M hydrochloric acid being 29.0, 40.0 and 85.0 min for reagent: metal mole ratios of 10, 100 and 1000, respectively.     

Selective and quantitative separation of zinc and lead from other elements by cation-exchange chromatography in hydrohalic acid-acetone solutions

Zinc and lead can be separated from Cd, Bi(III), In and V(V) by eluting these elements with 0.2M hydrochloric acid in 60% acetone from a column of AG50W-X8 cation-exchange resin, zinc and lead being retained. Mercury(II), Tl(III), As(III), Au(III), Sn(IV), Mo(VI), W(VI) and the platinum metals have not been investigated quantitatively, but from their distribution coefficients, should also be eluted. Vanadium(V), Mo(VI) and W(VI) require the presence of hydrogen peroxide. Zinc and lead can be eluted with 0.5M hydrochloric acid in 60% acetone or 0.5M hydrobromic acid in 65% acetone and determined by AAS; the alkali and alkaline-earth metal ions, Mn(II), Co, Ni, Cu(II), Fe(III), Al, Ga, Cr(III), Ti(IV), Zr, Hf, Th, Sc, Y, La and the lanthanides are retained on the column, except for a small fraction of copper eluted with zinc and lead. Separations are sharp and quantitative. The method has successfully been applied to determination of zinc and lead in three silicate rocks and a sediment.     

Separation of iron-52 from chromium cyclotron targets on the 2% cross-linked anion-exchange resin AG1-X2 in hydrochloric acid

Iron-52 can be separated from solutions of chromium cyclotron targets by eluting chromium, copper and radioactive impurities with 9.0M hydrochloric acid from a column containing 1.0 g of AG1-X2 anion-exchange resin. Iron-52 is retained and can then be eluted with 6.0M hydrochloric acid containing 0.05M hydrogen iodide or 0.05M sodium iodide. The separations are sharp and quantitative. Less than 2 microg of chromium will remain with the iron-52, from 2.0 g originally present.     

Liquid-liquid extraction of palladium(II) with N-n-octylaniline from hydrochloric acid media

N-n-Octylaniline in xylene is used for the extractive separation of palladium(II) from hydrochloric acid medium. Palladium(II) was extracted quantitatively with 10 ml of 2% reagent in xylene from 0.5-2 M hydrochloric acid medium. It was stripped from the organic phase with 1:1 ammonia and estimated spectrophotometrically with pyrimidine-2-thiol at 420 nm. The effects of metal ion, acids, reagent concentration and of various foreign ions have been investigated. The method affords binary separation of palladium(II) 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.     

Copper determination in natural water samples by using FAAS after preconcentration onto amberlite XAD-2 loaded with calmagite

A procedure for separation and preconcentration of trace amounts of copper in natural water samples, has been proposed. It is based on the adsorption of copper(II) ions onto a column of Amberlite XAD-2 resin loaded with calmagite reagent. This way amounts of copper within the range from 0.0125 to 25.0 μg, in a sample volume of 25 to 250 ml, and pH from 3.7 to 10.0 was concentrated as calmagite complex in a column of 0.50 g of Amberlite XAD-2 resin. Copper (II) ion was desorpted by using 5.0 ml of 2 mol l⁻¹ hydrochloric acid. Detection and determination limits of the proposed procedure for 250 ml sample volume were 0.15 and 0.50 μg l⁻¹, respectively. Selectivity test showed that (in the indicated concentration), calcium(II) (500 mg l⁻¹), magnesium(II) (500 mg l⁻¹), strontium(II) (50 mg l⁻¹), iron(III) (10 mg l⁻¹), nickel(II) (10 mg l⁻¹), cobalt(II) (10 mg l⁻¹), cadmium(II) (10 mg l⁻¹) and lead(II) (10 mg l⁻¹) did not interfere in copper determination by this procedure. Precision of the method, evaluated as the relative standard deviation by analyzing a series of seven replicates, was 2.42% for a copper mass of 1.0 μg in a sample volume of 100 ml. The accuracy of the proposed procedure was evaluated by means of copper determination in reference biological samples. The achieved results were in good agreement with certified values. The extractor system had a sorption capacity of 1.59 μmol of copper per gram of resin loaded with calmagite. The proposed procedure was applied for copper determination by FAAS in natural water samples. Samples were collected from different places of Salvador city, Bahia, Brazil. The achieved recovery, measured by the standard addition technique, showed that the proposed procedure had good accuracy. A good enrichment factor (50×) and simplicity are the main advantages in this analytical procedure.     

Decomposition of Cu(PCD)(2) extracted into IBMK and DIBK phases from hydrochloric acid media

The decomposition of the bis(1-pyrrolidinedithiocarbamato) copper(II) complex [Cu(PCD)(2)] extracted into isobutyl methyl ketone (IBMK) and di-isobutyl ketone (DIBK) from hydrochloric acid solution (0.01-8M) has been studied with UV-visible and ESR spectrometry. The mixed-ligand complex CuCl(PCD) is formed as an intermediate and CuCl(2) or CuCl3(-)(3), are formed as final products, in the decomposition of Cu(PCD)(2). The concentration of free hydrochloric acid dissolved in the extract has also been determined, and the effect of the free acid on the decomposition has been studied. The decomposition reaction of Cu(PCD)(2) extracted from hydrochloric acid solution can be thought of as a ligand substitution by Cl(-), and occurs with both IBMK and DIBK extraction.     

Redox-driven transport of copper ions in an emulsion liquid membrane system

A new redox-driven type of emulsion liquid membrane separation is described. Milligram amounts of copper(II) in 0.2 M hydrochloric acid were reduced to copper(I) in the presence of ascorbic acid (1 M≡1 mol l⁻¹). The copper solution was emulsified with a (1+4) mixture of toluene and n-heptane using Span-80 (sorbitan monooleate) as an emusifier. The resulting water-in-oil emulsion was dispersed in 0.2 M hydrochloric acid containing hydrogen peroxide and neocuproine (2,9-dimethyl-1,10-phenanthroline) by stirring for 10 min. The copper in the internal aqueous phase was selectively transported to the external one, leaving other heavy metals (e.g., Mn, Co, Ni, Cd and Pb) in the internal aqueous phase. After collecting the dispersed emulsion globules, they were demulsified by heating and the metals in the segregated aqueous phase were determined by graphite-furnace atomic absorption spectrometry (GFAAS). The selective transport of copper offered the multielement separation of trace heavy metals from a copper matrix, allowing the GFAAS determination of impurities at the 0.01% level in copper metal.     

Acetohydroxamate Resin as Column Packing for Ion Chromatography

A chelating resin with acetohydroxamate functional groups was synthesized and used as the stationary phase in ion chromatography for the determination of copper. As the reaction mechanism was mainly complexation, the coordination behavior of the synthesized resin toward Cu(II) was studied by means of EPR, IR and electronic spectrometry and potentiometry. The kinetic study shows that the resin is suitable for use in ion chromatography. We employed a resin column 250 mm long by 3 mm I.D. in conjunction with a mixture of hydrochloric acid and acetone as mobile phase for the determination of Cu(II). Detection of the chromatography system was carried out via post-column derivatisation of the column effluent with PAR at 520nm. The detection limit is 0.22ppm, and the relationship was linear in the range 0.25-1.20ppm. We investigated the effect of other metal ions, As(V), Cd(II), Cr(III), Hg(II), Ni(II), Pb(II) and Zn(II), or foreign ligands, EDTA, ascorbic acid, humic acid or sodium chloride on the determination of Cu(II) ion. A concentration column packed with acetohydroxamate resin combined with the above separation system was also used to determine of copper ion; the dynamic range is 2-15 ppb and the detection limit is 0.70ppb. The proposed system was applied to the analysis of Cu(II) in sea water.     

The separation of W(V) from HCl-KSCN medium on polyurethane foam sorbents for its spectrophotometric determination in steels and silicates

A simple procedure for selective sorption of tungsten is described. The method involves reduction of W(VI) to W(V) with tin(II) chloride (2%, w/v) at 8-9M hydrochloric acid, formation of the W(V)-SCN complex with 0.2M KSCN and its sorption on polyurethane foam within 20 min. The sorbed complex is then eluted with acidified acetone (1 ml of 1M hydrochloric acid and 8 ml of acetone) followed by addition of 1 ml of 0.1M KSCN to the eluent. The method has been applied to the spectrophotometric determination of tungsten in steels and silicates by measuring the absorbance of the eluted solution at 400 nm. Beer's law is obeyed for the range 0.1-12 mug W/ml. Other elements, e.g., Co(III) (50 mug/ml), Cu(II) (10 mug/ml), Ti(IV) (20 mug/ml), V(V) (10 mug/ml) and Mo(VI) (0.5 mug/ml) have no effect on the method. Interference of copper, up to 100 mug/ml has been eliminated by masking with thiourea and that due to molybdenum by prior separation with thioglycollic acid on PUF. The method has been verified with standard samples.     

Extractive separation of molybdenum as Mo(V) xanthate from Iron, vanadium, Tungsten, copper, uranium and other elements

A simple and selective extraction of molybdenum is described. Tungsten is masked with tartaric acid and molybdenum(VI) is reduced in 2M hydrochloric acid by boiling with hydrazine sulphate. Iron, copper and vanadium are then masked with ascorbic acid, thiourea and potassium hydrogen fluoride respectively. The molybdenum(V) is extracted as its xanthate complex into chloroform, from 1M hydrochloric acid that is 0.4M potassium ethyl xanthate. The complex is decomposed by excess of liquid bromine, and the molybdenum is stripped into alkaline hydrogen peroxide solution. The molybdenum is then determined by standard methods. Large amounts of Cu(II), Mn(II), Fe(III), Ti(IV), Zr, Ce(IV), V(V), Nb, Cr(VI), W(VI), U(VI), Re(VII) and Os(VIII) do not interfere. Several synthetic samples and ferromolybdenum have been rapidly and satisfactorily analysed by the method.