Quantitative separation of beryllium from magnesium,calcium, aluminium,iron and other elements by cation-exchange chromatography in nitric acid-methanol

Beryllium is separated from Mg, Ca, Mn(II), Fe(III), Al, Co(II). Zn. U(VI), La and Gd by elution with 2.0 M nitric acid in 70 % methanol from a column of AG50W-X8 sulphonated polystyrene cation exchanger, while the other elements are retained quantitatively. Sr, Ba, Sc, Y, the other lanthanides, Zr, Hf, Th, Ga, In, Cd and Ni(II) should also be separated according to their distribution coefficients or elution behaviour. Separations are sharp and recoveries quantitative from millimolar amounts down to 10 μg of beryllium. The separation of Ti(IV) and Cu(II) from beryllium is not satisfactory and requires rather large columns. Bi(III), Pb(II), Hg(II) and the alkali metals are eluted together with beryllium, but can be separated by other methods. Typical elution curves and results for the quantitative separation of binary synthetic mixtures are presented.     

Improved separation of cadmium from indium,zinc, gallium and other elements by anion-exchange chromatography in hydrobromic nitric acid mixtures

The separation of cadmium from indium, zinc and many other elements is considerably improved by eluting these elements with 0.1 M hydrobromic–0.5 M nitric acid solution from a column of AG1-X8 resin. Cadmium is retained very strongly and can be eluted with 2 M nitric acid or 1 M ammonia–0.2 M ammonium nitrate solution. Separations are sharp and quantitative and from microgram amounts up to 2 g of indium and zinc are separated from amounts of cadmium ranging from micrograms up to 100 mg on a 2-g (4.6 ml) resin column. Ga(II), Fe(III). Mn(II), Co(II), U(VI) and Ni(II) can be separated quantitatively from cadmium in the same way. The behaviour of numerous elements is discussed, with special attention to lead, and relevant elution curves and results from the analysis of synthetic mixtures are presented.     

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.     

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.     

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 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.     

Improvement of Am and Cm determination in soil samples

The determination of Am and Cm in a radiochemical procedure for the sequential analysis of Pu, Am, and Cm in soils was improved and optimized. This method uses only solvent extraction and extraction chromatography for the separation and cleaning of Am and Cm from soils up to 50 g sample weight. After leaching with 8M nitric acid, Pu is extracted with TOPO/cyclohexane. Am and Cm are extracted out of the remaining leaching solution at pH 1 with TOPO/cyclohexane, too. After backextraction with 2M nitric acid, Am and Cm are separated from traces of matrix elements, especially Fe, on a TRU-column, afterwards on a TEVA-column from lanthanides (TRU-resin and TEVA-resin of Eichrom Europe, SARL, Paris, France). The clean Am/Cm-fraction is electroplated and measured by alpha-spectrometry. The detection limit of this optimized procedure is 0.03 Bq/kg soil at a 95% confidence level.     

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.     

Liquid-liquid extraction of thorium (IV) with hexaacetato calix(6)arene

Thorium(IV) was quantitatively extracted at pH 7.5 with 0.0001M of hexaacetato calix(6)arene in toluene and after stripping with 0.05M nitric acid, it was determined spectrophotometrically at 545 nm with thoron. Thorium(IV) was separated from commonly associated elements in fission products like uranium(VI), cesium(I), lead(II), strontium(II) and cerium(IV) in varying proportions. The method is simple, rapid, selective and applicable for the microgram concentrations of thorium(IV).     

Separation of traces and minor amounts of lead from large amounts of zinc,indium, gallium and other elements on a low cross-linked anion-exchange resin

Lead is separated from gram amounts of Zn, In, Ga, Fe(III), Cu(II), Co(II), Mn(II), U(VI), Ca and Ba on a short column of AG1-X4 anion-exchange resin in the bromide form. Lead is retained from 0.2 M hydrobromic acid while the other elements are eluted completely with this reagent. Lead is then eluted with 2 M nitric acid. Separations are sharp and quantitative and, especially for gram amounts of zinc, much better than those obtained with an 8% cross-linked resin; up to 10 mg of lead can be separated from 2 g of zinc. Results are given for synthetic mixtures and lead is determined in several analytical grade chemicals.     

Separation of silver from zinc, cadmium, copper, nickel and other elements in nitric acid with a macroporous resin

Traces of silver and amounts up to 50 mg can be separated from up to gram amounts of Zn, Cu(II), Ni, Co(II), Mg, Be, Ti(IV), V(IV), Li and Na by eluting these with 2.0M nitric acid from a column containing 54 ml (20 g) of macroporous AG MP-50 cation-exchange resin of 100-200 mesh particle size, in the H(+)-form. Silver is retained and can be eluted with 0.5M hydrobromic acid in 9:1 v v acetone-water. Separations are sharp and quantitative and only a few microg of the other elements are found in the silver fraction. Cadmium and manganese (II) can also be separated quantitatively but show tailing and require larger elution volumes. Some typical elution curves and results of analyses of synthetic mixtures are presented.     

Extraction of rare earth elements by high molecular weight amines from nitric acid solutions

Extraction of trivalent rare earth elements by a high molecular weight primary amine /decylamine/ from 0.5–3M nitric acid solutions, containing potassium phosphotungstate /K₁₀P₂W₁₇O₆₁/, has been investigated. The effect of nitric acid and potassium phosphotungstate concentration of the organic solvent, and lanthanides ionic radii upon distribution coefficients has been studied. It has been established that decylamine solutions in chloroform can be used for the group isolation of rare earth elements and for their separation.     

Elution profiles of lanthanides with α‐hydroxyisobutyric acid by ion exchange chromatography using fine resin

Experiments were carried out using a strong acid cation exchange resin with a particle size of 75–150 μm, termed as “fine resin” in hydrogen ion form for the elution of individual lanthanides Sm, Eu, Gd, Tb, and Dy that are produced as fission products in the spent nuclear fuel and generated in the effluent during reprocessing of spent nuclear fuel. Batch experiments were carried out to study the effect of concentration of nitric acid on distribution coefficient. The distribution coefficient values for these individual lanthanides were determined in nitric acid medium in the concentration range of 0.01–4.0 N. Uptake of each individual lanthanide by resin was increased with increased nitric acid concentration from 0.01 to 0.5 N and remained similar from 0.5 to 1.0 N and decreased thereafter up to 4.0 N. Column experiments were also carried out using the same resin to study the parameters like pH of the eluent, flow rate, and resin bed height under isocratic elution conditions for eluting lanthanide elements using α‐hydroxyisobutyric acid as eluent. The results of this study have indicated the possibility for the elution of individual lanthanides.     

Adamantylcalixarenes with CMPO groups at the wide rim: synthesis and extraction of lanthanides and actinides

Starting from p-adamantylcalix[4]- and [6]arenes functionalized with carboxylic acid or ester groups at the adamantane nuclei, carbamoylmethylphosphine oxide (CMPO)-containing ligands of a novel type were synthesized. They were studied as extractants for a series of f-block elements including radioactive ¹⁵²Eu(III), ²⁴¹Am(III), ²³³U(VI), and ²³⁹Pu(IV). Tetrameric ligand 4b in which CMPO residues are connected to adamantane nuclei through methylene groups gave the best extraction results for lanthanides and actinides. For all the ligands the extraction efficiency does not decrease at higher nitric acid concentration. Although the discrimination between trivalent actinides and lanthanides is not good, all ligands are highly selective for thorium(IV) with the best separation factor achieved in the case of hexameric ligand 5 (D_Th/D_Ln>24).     

Extraction studies of trivalent ions from TALSPEAK medium using phsophonic acid-TBP solvent mixture

Indigenously synthesized extractant, phenyl (octyl) phosphonic acid (POPA) in tri-n-butylphosphate (TBP) and dodecane, has been investigated for the separation of americium from trivalent lanthanides in nitric acid medium as well as diethylene triaminepentaacetic acid (DTPA) and lactic acid mixture (TALSPEAK medium). Various experimental parameters like concentration of DTPA, lactic acid, TBP, nitrate ions and pH of the aqueous feed solution have been optimized to obtain the highest separation factor between americium and europium. Bulk actinide–lanthanide separation reagent, tetra (ethylhexyl) diglycolamide (TEHDGA), was equilibrated with simulated solution of americium and lanthanides, equivalent in concentration to the reprocessing waste originating from PHWR spent fuel. DTPA/lactic acid mixture was used to strip the metal ions from the loaded organic phase and re-extracted into POPA in TBP/dodecane to evaluate the separation factor of individual lanthanides with respect to americium. Very good separation factors between americium and trivalent lanthanides were obtained.     

Extraction of mercury(II) from aqueous thiocyanate solutions with 5-(4-pyridyl)nonane in benzene, and its subsequent atomic-absorption spectrometric determination

Tracer ( approximately 10(-8)M) mercury(II) can be quantitatively extracted with 5-(4-pyridyl)nonane in benzene from aqueous thiocyanate solutions that are up to 6M in HCl, 1M in H(2)SO(4) or 0.25M in HNO(3), in a single extraction. Optimal conditions for the extraction are given, based on a critical study of the relevant factors such as the effects of the acids, thiocyanate, salting-out and complexing agents and the reagent concentration. The mechanism underlying these extractions is discussed on the basis of the results obtained from partition and slope-analysis data. The extraction of the metal as Hg(PyN)(2)(SCN)(2) is indicated. The extracted mercury can be stripped from the non-aqueous layer with various aqueous solutions, including nitric acid (2M), sodium citrate ( 1M) and sodium thiosulphate (0.1 M). Common salts do not depress the extraction. Distribution coefficients and separation factors of several elements relative to mercury(II) are reported for media that contain the optimal concentrations of the mineral acids and are in 0.2M in potassium thiocyanate. The data have been applied for the determination of mercury in soil and water samples by atomic-absorption spectrometry.     

Separation of copper(II) from uranium(VI) and many other elements by cation-exchange chromatography in acetone-hydrobromic acid media: Improved selective separation of copper

Co(II), Ni(II), Mn(II), Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ti(IV), V(IV), Zr, Hf, Th, Al, Sc, Y, La, the lanthanides and also U(VI), which accompany copper(II) in hydrochloric acid-acetone mixtures, can be separated from copper by eluting copper(II) with 0.50 M hydrobromic acid in 85% acetone from a column of AG 50W-X8 resin, 200–400 mesh, while all these elements are retained by the column quantitatively. Separations are sharp and quantitative, as is demonstrated by results for some synthetic mixtures. Some relevant elution curves are presented.     

Thermal properties of complexes of lanthanides(III) and some of d-block elements with 5-chloro-2-methoxybenzoic acid

The thermal properties of 5-chloro-2-methoxybenzoates of lanthanides(III) and Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) were studied in air and nitrogen atmospheres. The complexes were obtained as mono-, di-, tetra- and pentahydrates with a metal to ligand ratio of 1:3 (in the case of lanthanides(III)) and 1:2 (in the case of d-block elements). They have colours typical for Ln³⁺ and M²⁺ ions. All complexes are polycrystalline compounds. When heated they dehydrate to form anhydrous salts which next in air are decomposed to the oxides of the respective metals while in nitrogen to the mixtures of metal oxides, oxychlorides and carbon. This revised version was published online in July 2006 with corrections to the Cover Date.     

Liquid-liquid extraction separation and sequential determination of plutonium and americium in environmental samples by alpha-spectrometry

A procedure is described by which plutonium and americium can be determined in environmental samples. The sample is leached with nitric acid and hydrogen peroxide, and the two elements are co-precipitated with ferric hydroxide and calcium oxalate. The calcium oxalate is incinerated at 450 degrees and the ash is dissolved in nitric acid. Plutonium is extracted with tri-n-octylamine solution in xylene from 4M nitric acid and stripped with ammonium iodide/hydrochloric acid. Americium is extracted with thenoyltrifluoroacetone solution in xylene at pH 4 together with rare-earth elements and stripped with 1M nitric acid. Americium and the rare-earth elements thus separated are sorbed on Dowex 1 x 4 resin from 1M nitric acid in 93% methanol, the rare-earth elements are eluted with 0.1M hydrochloric acid/0.5M ammonium thiocyanate/80% methanol and the americium is finally eluted with 1.5M hydrochloric acid in 86% methanol. Plutonium and americium in each fraction are electro-deposited and determined by alpha-spectrometry. Overall average recoveries are 81% for plutonium and 59% for americium.     

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.