Chromatography of inorganic ions on polyethyleneimine cellulose layer in hydrochloric acid — Ammonium thiocyanate media

Summary Thin-layer chromatographic behavior of 58 inorganic ions on polyethyleneimine (PEI) cellulose has been systematically surveyed in hydrochloric acid — ammonium thiocyanate media. In this media most of the ions distribute chromatographically on the layer. Ag(I), Hg(II), Pd(II), Au(III), Bi(III), Ru(III), Pt(IV), Nb(V), Ta(V), Mo(VI), and W(VI) are strongly retained, while alkali earths(II), Mg(II), As(III), Ti(IV), and Te(VI) are not absorbed to any great extent in this system. An interesting correlation was found between the R_f values on PEI-cellulose in the thiocyanate media and the paramagnetic moment of the rare earths(III). An oddeven fluctuation against the atomic number is also found for the heavy rare earths(III). Chromatographic separation of many inorganic ions of analytical interest is demonstrated in this system.     

Anion-exchange behavior of rare earths,thorium, protactinium and uranium in thiocyanate-chloride media

The anion exchange of rare earths(III), thorium(IV), protactinium(V) and uranium (VI) from thiocyanate-chloride media was investigated. The equilibrium, distribution study showed that the rare earths(III) and yttrium(III) were not significantly adsorbed on a basic anion-exchangc resin, while thorium(IV), protactinium(V) and uranium(VI) were strongly adsorbed. Adsorption from the thiocyanate-chloride solutions is in the order, U(Vl) > Pa(V) > Th(IV). The separation of rare earths(III) or yttrium(III), thorium(IV), protactinium(V) and uranium(VI) was successfully accomplished by column elution in thiocyanate-chloride media. A rapid and effective ion-exchange method for separating protactinium-233 from irradiated thorium(IV) is also presented.     

Thin-layer chromatographic separation of scandium, yttrium, the rare earths, thorium and uraniuin(VI)

The Chromatographic behaviour of scandium, yttrium, the rare earths, thorium and uranium(VI) in dioxan-hydrochloric acid and dioxan-nitric acid media on a plain cellulose thin layer has been investigated. The following separations are possible: scandium-yttrium-lanthanum, scandium-samarium-thorium, scandium-lanthanum-lutetium, yttrium-lanthanum-thorium, and lutetium-thorium-uranium(VI) with dioxan-12M hydrochloric acid (7:3) and scandium-samarium-thorium, scandium-yttrium-uranium(VI), lutetium-thorium, and scandium-lanthanum-thorium with dioxan-14M nitric acid (7:3). A single chromogenic spray (Arsenazo III) has been used for the detection of all the metal ions studied.     

Studies on the adsorption behaviour of trace amounts of cerium on manganese dioxide from aqueous solutions in the presence of complexing agents

Adsorption behaviour of trace amounts of cerium on manganese dioxide has been studied as a function of pH (1–10) in the presence of EDTA, oxalate, citrate, tartrate, cyanide and thiocyanate ions. The influence of their concentration on the adsorption has also been investigated. Maximum adsorption of cerium has been noticed at pH6. Under specific conditions, adsorption of other metal ions has been measured for comparison. Low distribution coefficients are obtained for Cs(I) and Hg(II) in the presence of oxalate, and for Cr(III) in the presence of thiocyanate ions. Based on these data, separation of cesium, chromium and mercury from rare earths and cerium scavenging in natural water or in waste water treatment can be achieved.     

Analytical applications of a liquid anion-exchanger for the separation of uranium(IV) in malonate solution

Uranium was quantitatively extracted with 4% Amberlite LA-1 in xylene at pH 2.5-4.0 from 0.001 M malonic acid. It was stripped from the organic phase with 0.01 M sodium hydroxide and determined spectrophotometrically at 530 nm as its complex with 4-(2-pyridylazo) resorcinol. Of various liquid anion-exchangers tested, Amberlite LA-1 was found to be best. Uranium was separated from alkali and alkaline earth metal ions, thallium(I), iron(II), silver, arsenic(III) and tin(IV) by selective extraction, and from zinc, cadmium, nickel, copper(II), cobalt(II), chromium(III), aluminium, iron(III), lead, bismuth, antimony(III) and yttrium by selective stripping. The separation from scandium, zirconium, thorium and vanadium(V) was done by exploiting differences in the stability of chloro-complexes.     

Separation of Thorium(IV) from Associated Elements Using Poly-(Dibenzo-18-Crown-6) and Column Chromatography from Picric Acid Medium

A simple column chromatographic method has been developed for the separation of thorium(IV) from associated elements using poly-(dibenzo-18-crown-6). The separations are carried out from picric acid medium. The adsorption of thorium(IV) was quantitative from 0.0005–0.05M picric acid. Amongst the various eluents tested, 2.0–8.0M HCl, HBr, 1.0–6.0M HClO₄ and 5.0M acetic acid were found to be particularly efficient for the quantitative elution of thorium(IV). The capacity of poly-(dibenzo-18-crown-6) for thorium(IV) was found to be 1.29±0.01 mmol/g of crown polymer. Thorium(IV) was separated from a number of cations in binary mixtures in which most of the cations showed a very high tolerance limit. It was possible to separate thorium(IV) from a number of cations such as lanthanum(III), yttrium(III), uranium(VI), beryllium(II) and barium(II) in multicomponent mixtures. The method was extended to the determination of thorium in monazite sand. It is possible to separate and determine 5 ppm of thorium(IV) by this method. The method is very simple, rapid, selective and has good reproducibility (approximately ±2%).     

A specific method for the separation of mercury(II) using a weakly basic cellulose ion exchanger

A systematic study of the behavior of many metal ions on the weakly basic cellulose exchanger DEAE in dilute thiocyanate media showed that few metal ions are adsorbed. The adsorption of mercury(II) allows a rapid and highly selective separation from about 40 metal ions. Quantitative results are quoted for the separation of ca. 100 μg of mercury(II) from milligram amounts of other metal ions; 100 μg to 10 mg of mercury(II) can be quantitatively separated from iron(III) in proportions of mercury(II): iron(III) = 100:1 to 1:8,000 on a column containing only 1 g of DEAE.     

Separation of tervalent rare earths and scandium from aluminium, iron(iii), titanium(iv), and other elements by cation-exchange chromatography in hydrochloric acid-ethanol

Tervalent rare earths and Sc are separated from the silicate-forming elements Al, Fe(III), Mg and Ti(IV), and also from Mn(II), U(VI), Be, Ga, In(III), Tl(III), Bi(III), Ni, Zn, Cu(II), Cd and Pb by cation-exchange chromatography. The other elements are eluted with 3.0 M HC1 containing 50% ethanol from a column of 60 ml of AG50W-X8 resin (200-400 mesh) while the rare earths are retained. Separation factors are larger than in aqueous hydrochloric acid. Th, Zr, Hf, Ba, Sr, Ca, K, and Rb are the only elements which accompany the rare earths group, but these can easily be separated by other methods which are described. Relevant distribution coefficients, elution curves and accurate results of quantitative separations of synthetic mixtures are presented.     

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.     

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.     

Separation of transition metal ions and preconcentration of platinum (IV) and chromium (III) on alumina-immobilized diethylenetriaminepentaacetic acid by ligand exchange

Summary Basic alumina-bonded diethylenetriaminepentaacetic acid (DTPA) has been utilized for the separation and preconcentration of some transition metal ions on the basis of ligand exchange. Breakthrough capacity and rate of sorption have been studied. The distribution coefficients of 16 transition metal ions have been determined in demineralized water, 0.01 M sodium citrate and in four different pH systems. On the basis of differences in Kd values some quantitative separations of metal ions have been achieved. The greater selectivity behaviour (higher Kd values) of the adsorbent for Pt(IV)and Cr(III) has been utilized for their preconcentration in the presence of other metal ions. The method has been employed for the recovery of Pt(IV) and Cr(III) from tapwater and sea-water samples.     

Chromatography of inorganic ions on cellulose phosphate layer in hydrochlorid acid and in acid ammonium thiocyanate media

Summary Thin-layers of an intermediately acidic cation exchanger, cellulose phosphate (P-cellulose), have systematically been used to study the chromatographic behavior of 58 inorganic ions in both hydrochloric acid and acid ammonium thiocyanate media (0.01–2.0 mol dm⁻³). In both solvent systems, the R _f values of many bivalent cations increase with increasing concentration of the acid and thiocyanate. Polyvalent metal ions including beryllium (II) and the others are strongly retained on the P-cellulose in the acid and thiocyanate systems tested. Palladium(II), mercury(II), ruthenium(III), rhenium(VII), arsenic(III), selenium(IV) and tellurium(IV) are not adsorbed on P-cellulose to any great extent. For silver(I), indium(III), gold(III), and platinum(IV), there are marked differences in the chromatographic behavior between hydrochloric acid and acid ammonium thiocyanate systems. Multicomponent separations conducted on P-cellulose plates with these eluents are presented.     

Extractive separation of Th(IV), U(VI), Ti(IV), La(III) and Fe(III) from Zarigan ore

In this study, the effects of various extraction parameters such as extractant types (Cyanex302, Cyanex272, TBP), acid type (nitric, sulfuric, hydrochloric) and their concentrations were studied on the thorium separation efficiency from uranium(VI), titanium(IV), lanthanum(III), iron(III) using Taguchi^??s method. Results showed that, all these variables had significant effects on the selective thorium separation. The optimum separations of thorium from uranium, titanium and iron were achieved by Cyanex302. The aqueous solutions of 0.01 and 1 M nitric acid were found as the best aqueous conditions for separating of thorium from titanium (or iron) and uranium, respectively. The combination of 0.01 M nitric acid and Cyanex272 were found that to be the optimum conditions for the selective separation of thorium from lanthanum. The results also showed that TBP could selectively extract all studied elements into organic phase leaving thorium behind in the aqueous phase. Detailed experiments showed that 0.5 M HNO₃ is the optimum acid concentration for separating of thorium from other elements with acidic extractants such as Cyanex272 and Cyanex302. The two-stage process containing TBP-Cyanex302 was proposed for separation thorium and uranium from Zarigan ore leachate.     

A novel multi-element coprecipitation technique for separation and enrichment of metal ions in environmental samples

A multi-element preconcentration-separation technique for heavy metal ions in environmental samples has been established. The procedure is based on coprecipitation of gold(III), bismuth(III), cobalt(II), chromium(III), iron(III), manganese(II), nickel(II), lead(II), thorium(IV) and uranium(VI) ions by the aid of Cu(II)-9-phenyl-3-fluorone precipitate. The Cu(II)-9-phenyl-3-fluorone precipitate was dissolved by the addition 1.0 mL of concentrated HNO₃ and then the solution was completed to 5 mL with distilled water. Iron, lead, cobalt, chromium, manganese and nickel levels in the final solution were determined by flame atomic absorption spectrometer, while gold, bismuth, uranium and thorium were determined by inductively coupled plasma mass spectrometer. The optimal conditions are pH 7, amounts of 9-phenyl-3-fluorone: 5 mg and amounts of Cu(II): 1 mg. The effects of concomitant ions as matrix were also examined. The preconcentration factor was 30. Gold(III), bismuth(III), chromium(III), iron(III), lead(II) and thorium(IV) were quantitatively recovered from the real samples. The detection limits for the analyte elements based on 3 sigma (n = 15) were in the range of 0.05-12.9 μg L⁻¹. The validation of the presented procedure was checked by the analysis of two certified reference materials (Montana I Soil (NIST-SRM 2710) and Lake Sediment (IAEA-SL-1)). The procedure was successfully applied to some environmental samples including water and sediments.     

Anion-exchange separation of gallium from indium,thallium, aluminium and other elements in malonic acid

Summary Systematic studies of gallium on Dowex-21K in malonate media are reported. On the basis of the value of the elution constant (E) it was separated from large number of metal ions. By selective sorption it was separated from the alkalis, alkaline earths, bismuth, thallium (I), mercury (II), iron (II) and germanium (IV). With water as eluant it was separated from cobalt, nickel, zinc, manganese and palladium, with ammonium chloride it was possible to separate it from copper, iron and vanadium, and with a specific eluant it was separated from lead and zirconium. Finally the sequential separation of gallium from thallium, aluminium and indium was accomplished.     

Anion-exchange behaviour and separation of metal ions on deae-cellulose in oxalic acid media

The anion-exchange behaviour of 30 metal ions on a weakly basic ion-exchanger (DEAE-cellulose) has been investigated in aqueous oxalic acid media over the concentration range 0.0010-0.50 M. There are marked differences in adsorbability between ter- and quadrivalent metal and bivalent metal groups; the system offers good prospects for group separations. The adsorptions are moderate, generally a few orders of magnitude lower than those on Dowex 1 (a strongly basic resin). Procedures for the separations Se(IV)Se(VI); As(III)As(V); multicomponent separations Mn(II)Co(II)Cu(II)Ti(IV)Zr(IV) and Cd(II)Zn(II)Cu(II), are given to demonstrate the versatility of the system.     

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.     

Extraction of molybdenum(VI) by 4-(5-nonyl)pyridine in benzene from aqueous mineral acid solutions containing thiocyanate ions

Extraction of Mo(VI) by 4-(5-nonyl)pyridine (NPy) in benzene from mineral acid solutions containing thiocyanate ions has been investigated at room temperature (23±2°C). From mineral acid (HCl, HNO₃, and H₂SO₄) solutions alone Mo(VI) is not extracted quantitatively while the presence of small amounts of KSCN in the system augments the extraction by a large factor. Stoichiometric studies indicate that ion-pair type complexes (NPyH)₂·[MoO₂(SCN)₄] are responsible for the extraction. Separation factors determined at fixed extraction conditions (0.1M Npy/C₆H₆–0.1M acid +0.2M KSCN) reveal that Ag(I), Cu(II), Co(II), Zn(II), Hg(II) and U(VI) are co-extracted while a clean separation from alkali metals, alkaline earths and some transition metals like Ln(III), Zr(IV), Hf(IV), Cr(III), Cr(VI) and Ir(III) is possible. Some of the complexing anions like oxalate, citrate, acetate, thiosulfate or ascorbate do not affect the degree of extraction of Mo(VI) allowing it to be recovered from diverse matrices.     

Synthesis,characterization and adsorption behaviour of TX-100 based Sn(IV) phosphate,a new hybrid ion exchanger

A new hybrid ion exchanger, Triton X-100 based tin(IV) phosphate (TX-100SnP) has been synthesized and characterized by ion exchange and physico-chemical methods such as ion exchange capacity, elution and concentration behaviour, IR, X-ray, TG/DTA and elemental analysis. Its adsorption behaviour has also been studied for some alkaline earths and heavy metal ions in different acidic media. It has been found generally more selective for metal ions as compared to tin(IV) phosphate prepared earlier. For Pb(II), Hg(II) and Fe(III) its selectivity has been found to be exceptionally good. On this basis, some binary separations have been performed involving these metal ions. Thermal studies show a high thermal stability of the material. It retains 54.54% of its i.e.c. at 200°C and 27.27% at 300°C.     

Preconcentration and separation of iron, zinc, cadmium and mercury, from waste water using Nile blue a grafted polyurethane foam

The present work describes a novel method for the incorporation of Nile blue A into polyurethane foam matrix. This foam material was found to be very suitable for the extraction of metal ions from aqueous solutions. The characterization of Nile blue A grafted foam and the effect of halide concentration, pH, shaking time, extraction isotherm and capacity have been investigated. This foam material was found to be suitable for the separation and preconcentration of iron (III), zinc (II), cadmium (II) and mercury (II) from waste water. The extraction was accomplished in (15-20) minutes. Iron was separated from acid medium (2-4 M HCl), zinc from (3-5 M HCl), cadmium from (4-6 M HCl) as thiocyanate complexes and mercury was separated from (1-2 M HCl) as chloride.