Anion-exchange behavior of various metals in hydrazoic acid media

The adsorption characteristics for 43 metals on a strongly basic ion-exchange resin Bio-Rad AG1 were examined in 0.5 M hydrazoic acid solution. The distribution coefficients for V(IV), Fe(III), Cu(II), Zn, Se(IV), Mo(VI), Pd(II), Cd, In(III), Rc(VII), Hg(II) and U(VI), which showed very strong adsorption except for Cd, were measured as a function of hydrazoic acid concentration over the range 0.05–0.5 M. Favorable differences in the distribution coefficients allow useful two- and three-component separations such as Co(II)-Fe(III), As(III)-V(IV), Cd-Zn, Cd- Hg(II), Te(IV)-Se(IV), Th-U(VI), Mn(II)-Mo(VI)-Re(VII), to be achieved on a small column.     

Quantitative separation of the alkali metals by cation-exchange chkomatography with bio-rex 40 resin : Application to silicate analysis

The application of BIO-REX 40, a phenolformaldehyde resin, to the quantitative separation of Li, Na, K, Rb and Cs is described. All five elements can be separated in a single procedure by using a 25-g (62-ml) resin column and eluting lithium with 500 ml of 1.00 M hydrochloric acid in 80% ethanol, sodium with 500 ml of 0.20 M hydrochloric acid, potassium with 250 ml of 0.70 M hydrochloric acid, rubidium with another 450 ml of 0.70 M hydrochloric acid and cesium with 500 ml of 4.0 M hydrochloric acid. Procedures are described for the accurate determination of alkali metals in silicate minerals, plant material and water. Al, Fe, Ti, Zr, V, Mo and some other elements are first separated by absorption as oxalato complexes on a column of AG1-X8 resin. The alkali metals are finally determined by gravimetry or atomic absorption spectrometry. Tables of distribution coefficients and quantitative results of analyses of synthetic mixture and standard silicate samples are presented together with typical elution curves.     

Removal of interferences in absorptiometric determination of bismuth with thorin

Bismuth can be separated by ion-exchange adsorption on Dowex 21 K resin from ca. 0.25 M HCl, after removal of volatile interferences by distillation in acid-oxidizing medium. Bismuth is eluted from the column with 1 M sulfuric acid. The method is useful in the absorptiometric determination of bismuth with thorin, as well as in other photometric methods.     

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 1M.The extraction coefficients are 92.5 at 7M hydrochloric acid and 251 at 6M 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 (H₂DOAA)⁺ [Ta(C₂O₄)₃ (HDOAA_n] (n=l or 2).     

A procedure for concentrating americium and curium combined with their separation from plutonium and fission products using a chelating resin

The effect of agitation time and resin quantity on the sorption of americium, curium and europium from mineral acid solutions, using a chelating resin based on aminopolystyrene and Arsenazo I was determined, and the behaviour of plutonium and fission products was investigated under optimum conditions with respect to the sorption of americium and curium. A procedure is proposed for concentrating americium and curium from dilute solutions, combined with their separation from iron, plutonium and fission products. The procedure consists of sorption on the chelating resin from 0.1–1N mineral acid solutions, washing of the resin with 0.5M oxalic acid and 11N sulfuric acid, and elution of americium and curium with 2M triammonium citrate.     

Étude des facteurs influençant la fixation de gallium(III) sûr résine dowex 50-x8 en milieu hc1-eau-dioxanne

The retention of gallium(III) on Dowex 50-X8 resin in 0.6 M HCl-dioxan media was studied as a function of the dioxan content. The ion-exchange in complexing medium (HC1) and in non-complexing medium (H₂SO₄) was studied; the determination of the distribution coefficients indicated the reactions occurring in the different media. Solvent uptake by Dowex 50-X8 (H⁺ and Ga(III) forms) from 0.6 M HCl-dioxan mixtures and the solvent composition in the resin were determined. The influence of the weak dielectric constant of dioxan proved to be most important; however, specific solvation phenomena were evident.     

Anion exchange separation of tin,antimony and tellurium

Tracer quantities of tin(IV), antimony(V) and tellurium(IV) are separated on Dowex-1 anion exchange resin in 0.1M oxalic acid. followed by 1M sulfuric acid.     

离子交换树脂的选择及柠檬酸溶液循环使用研究

用离子交换树脂法吸附柠檬酸溶液中的金属离子,苯乙烯系阳离子交换树脂的吸附性能较好,它对镍、铝离子的吸附容量均较大,且吸附前后柠檬酸溶液的浓度变化较小.静态条件下树脂对镍的吸附容量为16.83mg Ni/g干树脂,对铝为21.36mg Al/g干树脂;动态条件下树脂对镍的吸附容量为6.78mg Ni/g干树脂,对铝为31.8mgAl/g干树脂,吸附液流速为1m/h～3m/h.吸附后的柠檬酸溶液可循环使用.当用1mol/L硫酸解吸时,树脂对镍铝的解吸率可达90%以上.当硫酸中Ni2 为1.70mmol/L,Al3 为7.40mmol/L时,树脂的解吸率仍可达80%以上.     

Coulometric generation of molybdenum(v)

Molybdenum (V) was generated at a platinum cathode from 0.7 M molybdenum(VI) in 4 M sulfuric acid. A current efficiency of 99.9% was attained. A limiting current density of 0.05 mA/cm²/mM was found. The formal potential of the Mo(VI)–Mo(V) couple in 4 M sulfuric acid was determined to be ca. 0.55 V vs. N.H.E. Chromium(VI) solutions were titrated over a wide range of sample size and generating current. Amperometric titration curves were interpreted from current-voltage curves. Titrations could be performed in the presence of oxygen at the 1μeq. level. The effect of nitrate, perchlorate, orthophosphate, and chloride ions on the titration was determined.     

Determination of five trace elements in sea water after separation by anion-exchange chromatography

Summary A preconcentration technique involving anion-exchange in a thiocyanate medium has been developed for the determination of traces of vanadium, cobalt, copper, zinc, and cadmium in sea water. A conventional, small column containing a strongly basic anionexchange resin Amberlite CG 400 in the thiocyanate form allows the five trace metals to be concentrated from a 11 of sea water sample adjusted to 0.1M in thiocyanate and 0.1M in hydrochloric acid. Sorbed metals can be recovered simultaneously by elution with 140 ml of 2M perchloric acid. A stepwise elution technique is also developed, which permits removal of vanadium-copper-cobalt as a group, zinc, and cadmium to improve the selectivity of the separation. A simple scheme of separation for vanadium, copper, and cobalt is given, so that spectrophotometric determinations of these metals even with nonselective reagents may be feasible. Results are quoted on the preconcentration and subsequent spectrophotometric determination of the five metals in brine and sea waters.     

The separation and determination of glycolic and malic acids by ion-exchange chromatography

An ion-exchange chromatographic method for the separation of glycolic and malic acids was developed. It was found that the resin structure plays an important role in the resolution of the two acids. The best system for separating the acids was a 2.8-mm i.d., 122-cm long Amberlite CG-400 anion-exchange column. The acids in concentrations of 1–10% in 2 M formic acid gave linear peak area responses.     

Sine-wave polarographic determination of zirconium or niobium in aqueous media

The sine-wave polarographic determination of zirconium in aqueous media was investigated using solutions which were 0.55 – 5.5·10^-3M in zirconyl chloride and 1 M in potassium chloride and had been adjusted to pH 2.0 with hydrochloric acid. It was possible to determine zirconium in the concentration range of 0.05 to 0.4 mg per ml. The sine-wave polarographic behavior of zirconium in aqueous solutions in the pH range 2–3 is discussed. The sine-wave polarographic determination of niobium in aqueous media was investigated using concentrated sulfuric acid containing 5 to 0.1 mg of niobium per ml in a supporting electrolyte of citric acid; the determination of niobium was possible down to 0.1 mg of niobium per ml of concentrated sulfuric acid although the D.C. polarographic method was impractical for the determination of less than 0.5 mg of niobium per ml.     

The separation of rhodium and iridium by anion-exchange

The separation of rhodium and iridium in amounts of 100–1000 μg was achieved with a strongly basic anion-exchange resin. Rhodium was eluted with 0.8 M hydrochloric acid containing cerium(IV) sulfate. Iridium was recovered by eluting with concentrated nitric acid at 74°C, which minimized the formation of hydrolysis products. Recoveries of 98% or more were obtained for both metals.     

Copper salicylaldoxime and its use in the heterometric microdeterminatton of copper in the presence of foreign metals

1. The initial precipitation of copper-salicylaldoxime occurs at pH~1.5.Between pH 1.5 and 3.0, the precipitation is incomplete. A complete precipitation occurs in the pH-region of 3–10. Between pH 10.1 and 10.7 the precipitate redissolves At higher pH's a clear solution is obtained. 2. The solubility of copper salicylaldoximate is about ten times greater in 0.01M sulfuric acid (~0.5·10^-4 mol) than in 0.1M acetic acid. 3. In 10 ml of 0.1M acetic acid solution in the presence of ~99% foreign bivalent metals, one mg copper could be determined heterometrically with an error of 1–2%. 4. In the presence of ~95% alumin um or chromium, either citrate or tartrate (0.2M) were used as masking agents. In the presence of iron (~ 95%), clear end-points were obtained only with citrate. One mg of copper could be determined with an error of 0–3%. 5. Whichever pH is used, copper is not precipitated in the presence of ethylenediaminetetraacetate.     

Separation of lithium from sodium,beryllium and other elements by cation-exchange chromatography in nitric acid-methanol

Lithium can be separated from sodium, beryllium and many other elements by eluting lithium with 1 M nitric acid in 80% methanol from a column of AG50W-X8 sulphonated polystyrene cation-exchange resin. The separation factor is not quite as large as that in 1 M hydrochloric acid in 80% methanol, but many elements, such as Zn, Cd, In, Pb(II), Bi(III) and Fe(III), which form chloride complexes in 1 M HCl-80% methanol are retained quantitatively together with Na, Be, Mg, Ca, Mn(II), Al, Ti(IV), U(VI), and many other elements, when 1 M HNO3-80% methanol is used for elution of lithium. A method for the accurate determination of traces of lithium in rock samples is described, and some results obtained are presented together with relevant distribution coefficients, elution curves and results for the analysis of synthetic mixtures.     

Anion-exchange behaviour of the platinum metals and gold in hydrochloric acid-organic solvent media

The anion-exchange characteristics of the platinum metals and gold in hydrochloric acid media are described. The distribution coefficients of these elements were measured on the strongly basic anion-exchange resin Dowex 1 x 8 in mixtures of hydrochloric acid with water and several organic solvents, i.e., dimethylformamide, acetone, tetrahydrofuran, dioxan, methanol, acetic acid and pyndine. Based on these data the conditions most suitable for quantitative separation are indicated and discussed.     

Cation-exchange separations in organic solvent-dithizone media

Numerous elements can be adsorbed on a column of the strongly acidic cation-exchange resin Dowex 50 from a mixture consisting of tetrahydrofuran and 1 M nitric acid (19:1). These elements include Ag, Cu, Bi, Pb, rare earths, alkaline earth metals, alkali metals, U, Th, Fe, Co, Zn and Cd; Hg and Sb are not retained and so can be separated from the adsorbed elements. Fractionation of the adsorbed elements can be effected by using as eluent 0.01 M dithizone in tetrahydrofuran-1 M nitric acid(19:1);; the dithizonates of silver, copper and bismuth are selectively eluted while the other adsorbed metal ions are still retained. The technique is suitable for the separation of tracer and macro amounts of elements.     

Countercurrent extraction separation of some platinum group metals: part III

The bromo complexes of platinum(IV), palladium(II), rhodium(III), and iridium(IV) were prepared and studies were made on their distribution between hydrobromic acid solutions and various common solvents. The solvents employed were n-tributyl phosphate (TBP), methyl isobutyl ketone, amyl acetate, and various TBP-benzene mixtures. Distribution coefficients as a function of HBr concentration are given for each metal for each solvent system. A careful study of the measured distribution coefficients clearly showed that a number of binary and ternary mixtures of the metals can be resolved with a Craig countercurrent distribution apparatus. Rh-Pt and Rh-Pd mixtures in 4.38M HBr solutions were quantitatively separated on a Io-stage Craig apparatus using a 90% TBP-10% benzene solvent. Rh-Ir mixtures in 4.38 M HBr were resolved by 3 consecutive batch extractions with 90% TBP-10% benzene. Mixtures of Pd, Rh, and Ir in 4.38 M HBr were resolved in 90 stages using methyl isobutyl ketone as the solvent. Pd, Rh and Ir were recovered in 97.0, 87.6 and 94.5% yields, respectively. Mixtures of Pd, Rh and Pt in 4.38 M HBr were resolved in 90 stages using amyl acetate and methyl isobutyl ketone as solvents. Pd, Rh and Pt were recovered in 90.0, 96.0 and 94.0% yields, respectively. Two computer programs for the IBM 1620 Computer are given ; these facilitate the comparison of theoretical and actual solute distributions.     

A rapid routine method for the determination of sub-microgram and microgram amounts of beryllium in filter paper

A rapid routine method for the determination of submicrogram and microgram amounts of beryllium in filter paper smears is presented. Beryllium is determined fluorimetrically with 3,5,7,2',4'- pentahydroxyflavone (Morin). Many interfering elements are removed by adsorption on a strongly basic anion-exchange resin from 9N hydrochloric acid.     

Anion-exchange isolation of rare-earth elements from apatite minerals in methanol-nitric acid medium

Batch distribution coefficients, K_d, of rare-earth elements (REE) and other elements were determined radiochemically for a strongly basic nitrate anionexchange resin Dowex 1-X8 100–200 mesh, in nitric acid-methanol media of varying composition. This method was developed for the separate recovery of REE from apatite minerals. Calcium and other common elements of the apatite are eluted by a 5% (v/v) 7 M nitric acid-95% methanol mixture, while the REE are retained. The REE are recovered and separated into two fractions; the heavier REE by elution with a 45% nitric acid-55% methanol mixture, and a very clean fraction of La, Ce, Pr, Nd by elution with water.