Selective separation of uranium from other elements by cation-exchange chromatography in hydrobromic acid and hydrochloric acid-acetone mixtures

U(VI) can be separated from Ga, Fe(III), Bi, Pb, Cd, Zn, Cu(II) and Au(III) by quantitative elution with 0.50M HBr in 86% acetone or with 0.35M HBr in 90% acetone from a column of AG50W-X4 cation-exchange resin of 200-400 mesh particle size. U(VI) and many other ions are retained. U(VI) then can be eluted selectively with 0.50M HCl in 83% acetone or with 0.35M HCl in 85% acetone. Co(II), Mn(II), Mg, Ca, Ti(IV), Al, Zr, Th and La are quantitatively retained by the column. These elements then can be eluted with 5M HNO(3). At the higher acid concentration (0.50M) the separation between U(VI) and Li is not satisfactory but is excellent at the lower acid concentration; the U(VI) peak is sharper at the higher acid concentration. Separations are sharp and quantitative, as is demonstrated by results for some synthetic mixtures. Distribution coefficients and elution curves are presented.     

Quantitative separation of traces of lead,cadmium and many other elements from gram amounts of thallium by cation-exchange chromatography

Traces of lead and minor amounts up to 20 mg, can be separated from gram amounts of thallium by cation-exchange chromatography on a column containing only 2 g of AG50W-X4 resin. Thallium passes through the column in 0.1 M HCl in 40% acetone. The retained lead can be eluted with 3 M HCl or HNO₃. Other elements, including Cd, Zn, In, Ga, Cu(II), Fe(III). Mn(II), Co(II). Ni(II), U(VI) and Al, are retained quantitatively with lead. Only Hg(II), Au(III), the platinum metals, bismuth and elements forming oxyanions accompanying thallium. Results for the determination of trace elements in 99.999% pure thallium are presented.     

Quantitative separation of gold from cadmium, indium, zinc and other elements by cation-exchange chromatography in hydrochloric acid-acetone medium

Gold(III) can be separated from Cd, In. Zn, Ni, Cu(II), Mn(II), Co(II), Mg, Ca, Al, Fe(III), Ga and U(VI) by adsorbing these elements on a column of AG50W-X8 sulphonated polystyrene cation-exchange resin from 0.1M HCl containing 60% v v acetone, while Au(III) passes through and can be eluted with the same reagent. Separations are sharp and quantitative. The amounts of gold retained by the resin are between 1 and 2 orders of magnitude lower than encountered during adsorption from aqueous 0.1M HCl. Recoveries for mg amounts of gold are 99.9% or better and for ng amounts are still better than 99%, as shown by radioactive tracer methods. Hg(II), Bi, Sn(IV), the platinum metals and some elements which tend to form oxy-anions in dilute acid accompany gold. All other elements, though not investigated in detail, should be retained, according to their known distribution coefficients. Relevant elution curves, results of quantitative separations of binary mixtures and of recovery tests are presented.     

Quantitative separation of calcium from magnesium,aluminium, iron(III) and many other elements by cation-exchange chromatography in methanolic hydrochloric acid on a macroporous resin

Calcium can be separated from Mg, Al, Cu(II), Fe(III), Ga, Zn, Mn(II), Co(II), U(VI) and Ti(IV) by cation-exchange chromatography on a column of AG MP-50 macroporous resin. Sr, Ba, Sc, Y, the lanthanides, Zr, Hf and Th are retained together with calcium. The separation factor for the Ca—Mg pair in 3 M HCl containing 50% methanol is about 20 which is considerably larger than those obtained by other ion-exchange procedures. Separations with the cation-exchange resin are sharp and quantitative. A column containing only 2 g (5.4ml) of resin is sufficient to separate up to 0.2 mmol of calcium from 2 mmol of magnesium and larger amounts of Fe(III), Cu(II) and Zn. On a 10-g column, up to 2.5 mmol of calcium can be separated easily from similar and larger amounts of other elements. Distribution coefficients for calcium and magnesium with variation of cross-linkage and variation of methanol concentration are presented, together with relevant elution curves and results for synthetic mixtures.     

Separation of traces of manganese,cobalt, nickel and copper from gram amounts of tellurium by cation-exchange chromatography in hydrochloric acid/acetone media

Traces of Mn(II), Co(II), and Ni(II) and minor amounts (up to 20 mg of these elements are separated from gram amounts of tellurium by cation-exchange chromatography on small columns (3 g) of macroporous AG MP-50 resin or larger colunns (5 g) of microporous AG 50W-X8 resin. The trace elements are retained from 0.5 M HCl containing 70% acetone while tellurium passes through and is eluted completely with this solution. The trace elements are then eluted with 3.0 M HCl and can be determined by atomic absorption spectrometry. Copper (II) can also be separated but requires a 10-g column of AG MP-50 resin. Separations are sharp and quantitative and only microgram amounts of tellurium remain in the trace element fraction when a 3-g sample of tellurium dioxide is taken; 10-μg amounts of the trace elements were separated from such samples and determined with standard deviations of <1%. Relevant elution curves and results for the analysis of synthetic mixtures are presented.     

Radiochemical scheme for the quantitative isolation and gamma-spectrometric determination of La,Ga, Hf and Sc in neutron activation analysis of refractory materials

A new radiochemical scheme for the quantitative isolation of Ga, Sc, Hf and La, based on ion exchange and extraction chromatography, was devised, Ga and Sc were selectively retained on a Dowex 50WX2 [H⁺] column from 10 M HBr at 50°C. Ga was then eluted with ethyl acetate 0.25M in HBr, and scandium with 4M HBr. Hf was separated from 10M HBr at 75°C on a Kel-F column impregnated with tri-n-octylphosphine oxide (TOPO). The lanthamm fraction, after evaporation to dryness, was purified by ion-exchange chromatography in the system: Dowex 50WX8 [H⁺]−HCl. The effect of accompanying elements, and also the differences in the mechanism of uptake by the resin of various elements from concentrated HBr solution are briefly discussed. The scheme has been used for the determination of these four elements in refractory materials by activation analysis. As this procedure assured practically quantitative isolation of Ga, Sc, Hf and La, the addition of carriers and determination of chemical yield were unnecessary. The radiochemical purities of the respective fractions were as a rule high, and the measurements were performed by NaI(Tl) spectrometry. The detection limits were of the order of fractions of ppm, and could be considerably improved if necessary by increasing the counting time and sample weight.     

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.     

Distribution coefficients and ion-exchange selectivities for 46 elements with a macroporous cation-exchange resin in hydrochloric acid-acetone medium

Distribution coefficients with the macroporous cation-exchange resin AG MP-50 in HCl-acetone mixtures ranging from 0.2 to 4.0M HCl and from 0 to 95% acetone have been determined for 46 elements. The ion-exchange behaviour of the elements is discussed, some possible separations are indicated, and elution curves demonstrating separations of the combinations Au(III)BiZnPbSr; Rh(III)InGaCuNi and CdFe(III)LiAlYb are presented.     

Surfactant control of gas uptake: effect of butanol films on HCl and HBr entry into supercooled sulfuric acid

The entry of HCl into 60-68 wt % D(2)SO(4) and HBr into 68 wt % acid containing 0-0.18 M 1-butanol was monitored by measuring the fractions of impinging HCl and HBr molecules that desorb as DCl and DBr after undergoing H --> D exchange within the deuterated acid. The addition of 0.18 M butanol to the acid creates butyl films that reach approximately 80% surface coverage at 213 K. Surprisingly, this butyl film does not impede exchange but instead enhances it: the HCl --> DCl exchange fractions increase from 0.52 to 0.74 for 60 wt % D(2)SO(4) and from 0.14 to 0.27 for 68 wt % D(2)SO(4). HBr --> DBr exchange increases even more sharply, rising from 0.22 to 0.65 for 68 wt % D(2)SO(4). We demonstrate that this enhanced exchange corresponds to enhanced uptake into the butyl-coated acid for HBr and infer this equivalence for HCl. In contrast, the entry probability of the basic molecule CF(3)CH(2)OH exceeds 0.85 at all acid concentrations and is only slightly diminished by the butyl film. The OD groups of surface butanol molecules may assist entry by providing extra interfacial protonation sites for HCl and HBr dissociation. The experiments suggest that short-chain surfactants in sulfuric acid aerosols do not hinder heterogeneous reactions of HCl or HBr with other solute species.     

Separation of nickel from other elements by cation-exchange chromatography in dimethylglyoxime/hydrochloric acid/acetone media

Nickel can be separated from Zn, Co, Cu(II), Mn(II), Fe(III), U(VI) and other elements which readily form chloro complex ions, by eluting them with 0.5 M HCl/93% acetone from AG50W-X4 resin. Nickel is then eluted selectivity with 0.5 M HCl/95% acetone containing 0.1 M dimethylglyoxime, while the alkali and alkaline-earth elements, Al, Ti(IV), Sc, Y, La, lanthanides, Zr, Hf and Th are still retained. Separations are sharp and quantitative.     

Selective separation of indium from zinc, lead, gallium and many other elements by cation-exchange chromatography in hydrohalic acid-acetone medium

Indium can be separated from Zn, Pb(II), Ga, Ca, Be, Mg, Ti(IV), Mn(II), Fe(III), Al, U(VI), Na, Ni(II) and Co(II) by selective elution with 0.50M hydrochloric acid in 30% aqueous acetone from a column of AG50W-X8 cation-exchange resin, all the other elements being retained by the column. Lithium is included in the elements retained by the column when 0.35M hydrochloric acid in 45% aqueous acetone is used for eluting indium, but the elution of indium is slightly retarded. Ba, Sr, Zr, Hf, Th, Sc, Y, La and the lanthanides, Rb and Cs should also be retained according to their distribution coefficients. Cd, Bi(III), Au(III), Pt(IV), Pd(II), Rh(III), Mo(VI) and W(VI) can be eluted with 0.20M hydrobromic acid in 50% aqueous acetone before the elution of indium, and Ir(III), Ir(IV), As(III), As(V), Se(IV), Tl(III), Hg(II), Ge(IV), Sb(III) and Sb(V), though not investigated in detail, should accompany these elements. Relevant distribution coefficients and elution curves and results for analyses of synthetic mixtures of indium with other elements are presented.     

Quantitative separation of Al, Ga, In, and Tl by cation exchange chromatography in hydrochloric acid-acetone

Up to 4 mmole (1 mmole each) of tervalent Al, Ga, In and Tl are separated from each other on a 60-ml column of AG50W-X8 resin of 200-400 mesh particle size by cation-exchange chromatography in hydrochloric acid-acetone mixtures. Separations are very sharp and without tailing. Recoveries for amounts from 1-100 mg average 100.0 +/- 0.1 % for the analysis of synthetic mixtures. An anion-exchange method is described for the separation of gallium from the hydrochloric acid-acetone eluate. Relevant cation-exchange distribution coefficients, anion-exchange coefficients for gallium in hydrochloric acid-acetone, an elution curve for all four elements and results of quantitative separations of synthetic mixtures are presented.     

Matrix reactivity of AlF and AlCl in the presence of HCl and HBr: generation and characterization of the new Al(III) hydrides HAlFCl,HAlFBr, and HAlClBr and the monomeric mixed Al(III) halides AlX(2)Y (X,Y = F,Cl, or Br)

The spontaneous and photolytically induced reactions of AlF and AlCl in the presence of HCl and HBr in solid argon matrices were followed and the products identified and characterized by means of IR spectroscopy. Quantum mechanical calculations allow for a further evaluation of the properties of the reaction products. These are the adducts AlF.HCl, AlF.HBr, and AlCl.HBr, representing the products of spontaneous reactions, and the trivalent Al(III) hydrides HAlFCl, HAlFBr, and HAlClBr, which were formed upon photoactivation of these complexes. All three hydrides are planar molecules (C(s)() symmetry) with bond angles in agreement with the predictions of the VSEPR theory. In addition, the mixed halides AlFCl(2), AlFBr(2), and AlClBr(2) were formed upon photolysis. The bisadducts AlF.(HCl)(2) and AlF.(HBr)(2) are likely to be the precursors to these species.     

Determination of impurities in high-purity gold, with a gas-stabilized low-temperature arc

A gas-stabilized arc with aerosol supply has been used for emission spectrometric determination of Al, B, Be, Co, Cr, Fe, Ga, In, Mg, Mn, Ni, Pd, Rh and Zn, as impurities in high-purity gold. Two analytical procedures were compared: (a) direct aspiration of dissolved samples containing 2% of gold and 0.25M KCl as buffer, and (b) separation of impurities by ether extraction of gold from 1M HCl followed by impurity determination with a stabilized arc. Limits of detection, precision and recovery of the extraction procedure are given.     

Separation of trivalent rare earths plus sc(iii) from al,ga,in,tl, fe,ti, u and other elements by cation-exchange chromatography

A method is presented for the quantitative separation of the trivalent rare earths plus Sc(III) as a group from Al(III), Ga(III), In(III), Tl(III), Fc(III). Ti(IV), U(VI), Be(II). Mn(II), Co(II), Cu(II), Ni(II). Zn(II). and Cd(II). These elements can be eluted from a cation-exchange column with 1.75 N HCl, while the rare earth group elements are retained. Numerous other elements not investigated have low distribution coefficients in 1.75 N HCl and therefore should be separated by the same procedure; Th(IV) is retained by the column when the rare earths are elutcd with 3.0 N HCl. The only elements which partially accompany the rare earths plus Sc(III) are Zr(IV), Hf(IV), Sr(II), and Ba(II) ; these have to be separated by special procedures. The method is suitable for accurate reference analysis over a wide range of concentrations.     

Evaporation of water and uptake of HCl and HBr through hexanol films at the surface of supercooled sulfuric acid

Vacuum evaporation and molecular beam scattering experiments have been used to monitor the loss of water and dissolution of HCl and HBr in deuterated sulfuric acid at 213 K containing 0 to 100 mM hexanol. The addition of 1-hexanol to the acid creates a surface film of hexyl species. This film becomes more compact with decreasing acidity, ranging from approximately 62% to approximately 68% of maximum packing on 68 to 56 wt % D(2)SO(4), respectively. D(2)O evaporation from 68 wt % acid remains unaltered by the hexyl film, where it is most porous, but is impeded by approximately 20% from 56 and 60 wt % acid. H --> D exchange experiments further indicate that the hexyl film on 68 wt % acid enhances conversion of HCl and HBr into DCl and DBr, which is interpreted as an increase in HCl and HBr entry into the bulk acid. For this permeable hexyl film, the hydroxyl groups of surface hexanol molecules may assist uptake by providing extra sites for HCl and HBr hydrogen bonding and dissociation. In contrast, HCl --> DCl exchange in 60 wt % D(2)SO(4) at first rises with hexyl surface coverage but then drops back to the bare acid value as the hexyl species pack more tightly. HCl entry is actually diminished by the hexyl film on 56 wt % acid, where the film is most compact. These experiments reveal a transition from a porous hexanol film on 68 wt % sulfuric acid that enhances HCl and HBr uptake to one on 56 wt % acid that slightly impedes HCl and D(2)O transport.     

Highly accurate determination of trace amounts of uranium in standard reference materials by spectrophotometry with chlorophosphonazo III after complete separation by anion and cation exchange chromatography

Summary A method is described for the highly accurate determination of trace amounts of uranium in standard reference materials. The uranium is separated from the bulk elements by anion-exchange chromatography, eluting most elements with 6 M hydrochloric acid and iron(III) with 0.5 M hydrochloric acid in 90% acetone. After elution of uranium with 0.1 M hydrochloric acid, residual traces of other elements are separated by a very selective cation-exchange procedure using a 3 g resin column. Finally the uranium is determined in the hexavalent state by spectrophotometry at 672 nm of its complex with chlorophosphonazo III at pH 1.1±0.2 in the presence of DTPA. Results are very accurate and precise even on a semi-routine basis. Relevant elution curves and results are presented for recovery tests and for the analysis of the 10 South African UREM standard materials.

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Methode hoher Genauigkeit zur spektalphotometrischen Bestimmung von Uranspuren in Standard-Referenzmaterialien mit Chlorphosphonazo III nach Abtrennung durch Anionen- und Kationen-Austausch-Chromatographie

Zusammenfassung Das Uran wird von den Hauptelementen durch Anionenaustausch abgetrennt, wobei die meisten Elemente mit GM HCl und Eisen(III) mit 0,5 M HCl in 90 %igem Aceton eluiert werden. Nach der Elution von Uran mit 0,1 M HCl werden die restlichen Spuren anderer Elemente durch ein selektives Kationenaustauschverfahren (3 g Harz) abgetrennt. Das Uran wird schließlich in der sechswertigen Form als Chlorphosphonazo-III-Komplex in Gegenwart von DTPA bei 672 nm (pH 1,1±0,2) spektralphotometrisch bestimmt. Selbst bei halbroutinemäßiger Ausführung werden sehr genaue Resultate erhalten (Wiederfindung 99,7–100%). Analysenergebnisse für 10 Südafrikanische Standardmaterialien werden angegeben.

Dedicated to Prof. Dr. E. Blasius on occasion of his 60th birthday     

Quantitative separation of gallium from zinc, copper, indium, iron(III) and other elements by cation-exchange chromatography in hydrobromic acid-acetone medium

Gallium can be separated from Zn, Cu(II), In, Cd, Pb(II), Bi(III), Au(III), Pt(IV), Pd(II), Tl(III), Sn(IV) and Fe(III) by elution of these elements with 0.50M hydrobromic acid in 80% acetone medium, from a column of AG50W-X4 cation-exchange resin. Gallium is retained and can be eluted with 3M hydrochloric acid. Separations are sharp and quantitative except for iron(III) which shows extensive tailing. With 0.20M hydrobromic acid in 80% acetone as eluting agent, all the species above except iron(III) and copper(II) can be separated from gallium with very large separation factors. Only a 1-g resin column and small elution volumes are required to separate trace amounts and up to 0.5 mmole of gallium from more than 1 g of zinc or the other elements. Hg(II), Rh(III), Ir(IV), Se(IV), Ge(IV), As(III) and Sb(III) have not been investigated, but should be separated together with zinc according to their known distribution coefficients. Relevant elution curves, results for the analysis of synthetic mixtures and for amounts of some elements remaining in the gallium fraction are presented.     

Extraction of europium from mixed acids and mixed aqueous—Organic media

The extraction of Eu with Amberlite LA-2, TBP and HDEHP from HF, HCl, HBr, H₂SO₄, CH₃ COOH and KI solutions was investigated. The extraction of Eu with TBP and LA-2 is small over a wide range of concentrations. The extraction of Eu with HDEHP from HCl, HBr, and H₂SO₄ is inversely proportional to the third power of the acid concentration, while the extraction from KI is proportional to the square of the extractant concentration. The extraction by the three extractants from H₂SO₄ in presence of small amounts of hydrogen halides is small. These extraction data can be used to separate Eu from Th and many of the fission products. The presence of water-miscible alcohols and acetone generally increases the extraction of Eu from H₂SO₄ and KI solutions.     

Photoelectron spectroscopy and density functional theory of puckered ring structures of Group 13 metal-ethylenediamine

The ethylenediamine (en) complexes of Al, Ga, and In atoms were prepared in laser-vaporization supersonic molecular beams and studied with pulsed field ionization zero electron kinetic energy photoelectron spectroscopy and density functional theory. Several conformers of each metal complex are obtained by B3LYP calculations, and a five-membered cyclic structure is identified by combining the experimental measurements and theoretical calculations. Adiabatic ionization potentials, vibrational frequencies, and bond dissociation energies are determined for the ring structure. The ionization potentials of the Al, Ga, and In species are measured to be 32 784 (5), 33 324 (5), and 33 637 (7) cm(-1), respectively, and metal-ligand dissociation energies of the ionic and neutral complexes are calculated to be 60.2/16.2 (Al(+)/Al), 55.5/13.0 (Ga(+)/Ga), and 50.0/11.4 (In(+)/In) kcal mol(-1). Metal-ligand stretch and bend as well as a number of ligand-based vibrations are measured. Harmonic frequencies and anharmonicities of the M(+)-N (M=Al,Ga,In) stretch are determined for all three M(+)-en ions and the C-C-N bend of Ga(+)-en and In(+)-en. In comparison to monodentate methylamine, the bidentate binding of ethylenediamine leads to a significantly lower ionization potential and higher metal-ligand bond strength of the metal complexes.