Separation of Mercury(II) as Chloride from Zinc(II), Cadmium(II), Gold(III), and Thallium(III) by Extraction in High-Molecular-Weight Amines

Abstract

The extraction behavior of Zn(II), Cd(II), Hg(II), Au(III), and Tl(III) has been studied at different HCl molarities in some commercially available liquid anion exchangers. The effect of such variables as the type of amine, molarity of HCl, amine concentration, and organic diluent on extraction has been explored to suggest the best conditions of separation of Hg(II) from Zn(II), Cd(II), Au(III), and Tl(III).     

Extraction Behavior of Zinc(II), Cadmium(II), Mercury(II), Indium(III), and Thallium(III) as Thiocyanates in High-Molecular-Weight Amines and Some Mutual Binary Separations

Abstract

The extraction behavior of Zn(II), Cd(II), Hg(II), In(III), and Tl(III) has been studied at different NH₄CNS molarities in some commercially available liquid anion exchangers. The effect of such variables as the type of amine, molarity of NH₄CNS, and pH of aqueous phase and organic diluent on extraction has been explored to achieve the best conditions of some mutual binary separations of analytical and radiochemical interest.     

Gel-Liquid Extraction and Separation of U(VI), Th(IV), Ce(lll), and Co(ll)

Abstract

The gel-liquid extraction of U(VI), Th(IV), Ce(III), and Co(II) has been investigated in the 0.01 to 2 M HNO₃ range using a gel prepared by swelling styrene divinylbenzene with di-(2-ethylhexyl)phosphoric acid. Obtained results indicate that all of the tested cations can be extracted and that the extraction coefficients increase in the order Ce(III) < Co(II) < Th(IV) < U(VI) and generally decrease with acidity. Under suitable conditions, separation of Th(IV), Ce(III), or Co(II) from U(VI) or of Th(IV) from Ce(III) can be achieved. Kinetic studies indicate that the extraction process is controlled by a progressive shell sorption mechanism.     

LIQUID-LIQUID EXTRACTION OF Ag(I), Hg(II), Au(III) AND Pd(II) BY SOME OLIGOTHIA MACROCYCLIC LIGANDS INCORPORATING AROMATIC AND HETEROAROMATIC SUBUNITS*

ABSTRACT

A series of hydrophobic tri- to hexa-dentate sulfur containing macrocyclic ligands incorporating aromatic and heteroaromatic subunits have been studied with respect to their extraction properties toward Ag(I), Hg(II), Au(III), and Pd(II) in aqueous//organic systems. The stoichiometry of extracted species and their extraction constants have been determined. The different ligands are compared with structure related open-chain compounds. The influence of substitution, solvent, and anion on the extraction equilibrium is also discussed providing a basis for future design of selective extractants and for die development of improved separation methods. The extractability of the various metal ions strongly depends on the nature and the number of donor atoms of the corresponding ligands and on the properties of the metal ion itself. In some cases, simple open-chain ligands show extraction properties comparable to the present macrocycles. A trithia crown with incorporated benzo subunit highly prefers Ag(I) to Hg(II). Furthermore a distinct selectivity for Au(ni) and Hg(II) over Pd(II) with pyridine substituted macrocycles was found.     

SOLVENT IMPREGNATED RESINS CONTAINING DI(2-ETHYL-HEXYL)PHOSPHORIC ACID.II. STUDY OF THE DISTRIBUTION EQUILIBRIA OF Zn(II), Cu(II) AND Cd(II).

ABSTRACT

The extraction of Zn(II), Cu(II) and Cd(II) from nitrate solutions at 0.1 M ionic strength by impregnated resins containing di(2-ethylhexyl)phosphoric acid has been studied at 25 °C.

The distribution coefficient was determined as a function of both pH and extractant concentration in the resin phase. The data were analyzed graphically using the slope analysis method, and numerically using the program LETAGROP-DISTR. The composition of the extracted species in the resin phase has been determined.

Analysis of the results showed that the extraction of these metal ions can be explained assuming the formation of metal complexes in the resin phase with a general composition ML₂(HL) _q where q takes different values depending on the metal. An extraction reaction is proposed and the extraction constants of these species are given.

Finally, a comparison between the extraction of Zn(II), Cu(II) and Cd(II) by di(2-ethylhexyl)phosphoric acid into Amberlite XAD2 and the extraction using organic solvents has been made.     

LIQUID-LIQUID EXTRACTION OF GOLD(III) AND ITS SEPARATION OVER COPPER(II), IRON(III), AND ZINC(II) USING THIOUREA DERIVATIVES FROM CHLORIDE MEDIA

ABSTRACT

Selective liquid-liquid extraction of Au(III) from aqueous chloride media (1 mol/L NaCl) into cumene by thiourea derivatives namely 2a-c (N-thiocarbamoylbenzamidine derivatives), 3a-f (N-benzoylthiourea derivatives) has been investigated in detail. Marked differences in the metal extraction are noted using these organic compounds with respect to their structural variation. The extraction behaviour of Au(III) with extractants 2a-c and 3a-f followed the order : 2b> 2a>2c and 3e≈ 3c≈ 3d >3a >3f≈3b, respectively. The organic reagent 2a and 3c were selected for further detailed studies owing to their better strippability behaviour. Optimum conditions such as structure of the organic extractant, aqueous phase pH, diluent, time of equilibration, metal concentration, extractant concentration, effect of other metal cations were established for extraction separation of Au(III). Experimental data have been treated graphically and numerically by means of the computer programme LETAGROP-DISTR, and can be explained by assuming the formation of the species AuCl₃L and AuCl₃L₂ for 2a-c and AuCl₃L₂ for 3a-f derivatives. The lack of interference from even appreciable amounts of possible base metals such as Cu(II), Zn(II) and Fe(III) may be considered an outstanding advantage of the method for separation of gold from these metals using 2a and 3c.     

DISTRIBUTION COEFFICIENTS AND ION EXCHANGE BEHAVIOUR OF SOME CHLORIDE COMPLEX FORMING ELEMENTS WITH BIO RAD AG50W-XB CATION EXCHANGE RESIN IN MIXED NITRIC-HYDROCHLORIC ACID SOLUTIONS

Cation exchange equilibrium distribution coefficients are presented for the chloride complex forming elements Au(III), Tl(III), Hg(II), Bi(III), In, Cd, Zn, Pb(II), Fe(III) and Ga with a microporous (gel-type) resin of 8% DVB crosslinkage in hydrochloric-nitric acid mixtures ranging from 0.02M to 0.50M and from 0.20M to 2.0M concentrations, respectively. Separations which are possible by using mixtures and pure hydrochloric acid as eluting agents are demonstrated by three elution curves separating the mixtures Hg(II)-Cd-Zn; Au(III)-Bi(III)-Pb(II) and Tl (III)-In-Zn and the exchange behaviour of the elements is discussed.     

Solvent Extraction Separation of Beryllium(ll) from Aluminum(lll) by Cyanex 921 (TOPO)

ABSTRACT

Cyanex 921, a neutral extractant, has been used for the extraction of beryllium(II)from basic media and employed for the separation of beryllium(II) in the presence of aluminum(III). Cyanex 921 diluted in cyclohexane extracted beryllium(II) in the 8–10 pH range and aluminum(III) between 4–5 pH. The selectivity of beryllium(II) over aluminum(III) was high in the 8–10 pH range. The extracted beryllium(II) was stripped with 0 M NaOH without any significant loss of the ligand while loaded aluminum(III) was stripped with 2 M HC1. The extractability of beryllium(II) and aluminum(III) was also studied separately as a function of pH, temperature, equilibration time, and stripping ability with NaOH, KOH, HCI, HNO₃, H₂SO₄, and HCIO₄. Based on these results, a sequential method was developed for the separation of beryllium(II) from aluminum(III).     

Elution Behavior of Metal Ions with Mixed Glycine-Nitric Acid Eluents in Dowex 50W-X8 Column: Separation of Th(IV), Ce(IV), Bi(III), Fe(III), and Al(III)

Abstract

Distribution coefficients (K) determined by the batch technique in acidic glycine media using Dowex 50W-X8 cation exchanger (H⁺?form, 100–200 mesh size) revealed that this medium can effectively be employed to separate a number of tetravalent and trivalent metal ions from bivalent metal ions. In fixed glycine (0.40 M) and varying concentration of nitric acid (0.10 to 1.0 M), a number of mixtures containing two or three metal ions were resolved on columns using about 8 g of exchanger. In 0.40 M glycine-1.0 M HNO₃ medium, Th(IV)/Ce(IV) were separated from Al(III)/Fe(III)/Bi(III)/Co(II)/Ni(II)/Cu(II)/Zn(II)/Cd(II)/Hg(II)/Pb(II)/Ag(I) and also Al(III)/Bi(III) from a number of divalent metal ions. In 0.40 M glycine-0.50 M HNO₃ medium, the resolution of following ternary mixtures were also achieved: Th(IV)/Ce(IV)-Al(III)/Bi(III)-Fe(III)/Co(II)/Ni(II)/Cu(II)/Zn(II)/Cd(II)/Hg(II)/Pb(II)/Ag(I). Th(IV)/Al(III)/Fe(III)/Bi(III) were also separated from other divalent metal ions in 1.60 M glycine-0.50 M HNO₃ medium. The values of K, elution characteristics of metal ions, elution curves, and the results of the resolution of a number of mixtures of metal ions along with standard deviations are reported.     

IMPREGNATED RESINS CONTAINING DI-(2-ETHYLHEXYL) THIOPHOSPHORIC ACID FOR THE EXTRACTION OF PALLADIUM(H). II. SELECTIVE PALLADIUM(II) RECOVERY FROM HYDROCHLORIC ACID SOLUTIONS

ABSTRACT

The extraction of Pd(II) from HC1 solutions by impregnated resins containing di-(2-ethylhexyl) thiophosphoric acid (DEHTPA or HL) on the Amberlite XAD2 polymeric support has been studied. Graphical and computer analysis with the program LETAGROP-DISTR demonstrated that the Pd(II) extraction can be explained by the formation of metal complexes in the resin phase having the composition PdL₂(HL)₂. DEHTPA/XAD2 resins extracted Pd(II) in the presence of other metals: Pt(IV), Rh(III), Cu(II), Fe(III) as well as Zn(II). The stripping of Pd(II) loaded on the organic phase and the lifetime of the resins were also investigated.     

Thin-Layer Chromatography of Metal Ions on Stannic Arsenate: Quantitative Separation of Hg(II) from Cd(II), Zn(II), and Cu(II)

Abstract

Stannic arsenate thin layers (0.25 mm) have been applied for the chromatographic studies of 42 metal ions without using any binder. As a result, some important binary separations, such as Cd-Sb, V-Nb, V-Ta, Ni-Fe, Pd-Nb, Hg-Pb, and Pb-Mo, have been performed. Quantitative separation of Hg from Cd, Zn, and Cu has also been made by this technique. The study has been found to give reproducible results on refluxed and nonrefluxed samples of stannic arsenate used simultaneously.     

Poly(4-sodium styrene sulfonate-co-4-acryloylmorpholine). Synthesis,Characterization, and Metal Ion Retention Properties

Abstract

A novel resin poly(sodium 4-styrene sulfonate-co-4-acryloyl morpholine) was synthesized through a radical solution polymerization in solution and studied as an adsorbent under uncompetitive and competitive conditions by batch and column equilibrium procedures for the following divalent metal ions Cd(II), Zn(II), Pb(II), and Hg(II), and trivalent Cr(III). For all metal ions, the adsorption was strongly influenced by the pH. The maximum retention capacity, 3.29 mmol of metal ion/g, was obtained for Zn(II) at pH 5 by batch equilibrium procedure. For both the batch and column procedures, the retention behavior was similar for Cd(II), Cr(III), Zn(II), and Pb(II).     

Synthesis,Composition, and Ion-Exchange Behavior of Thermally Stable Zr(IV) and Ti(IV) Arsenophosphates: Separation of Metal Ions

Abstract

Two new inorganic ion-exchange materials, Zr(IV) and Ti(IV) arsenophosphates, have been synthesized. They are reproducible in behavior and possess excellent thermal stability. Their tentative structures have been proposed based on pH titrations, thermogravimetry, chemical analysis, IR studies, and other ion-exchange properties. Distribution studies of some metal ions have also been made on the basis of which several useful binary separations have been achieved such as Fe(III) from VO(II), Cu(II), and Zn(II); Pb(II) from Cu(II), Hg(II), and Zn(II); Ti(IV) from UO₂(II) and Ce(IV); and Mg(II) from Sr(II) and Ba(II).     

1,5-Bis(2,5-Difluorophenyl)-3-Mercaptoformazan. A New Tetrafluorinated Dithizone Analogue

Abstract

1,5-Bis(2,5-difluorophenyl)-3-mercaptoformazan (2,2′, 5.5′-tetrafluorodithizone, F₄ H₄ Dz) has been synthesized; its electronic spectra was found to be significantly different from that of dithizone. Its pH_½ in chloroform (8.4) and in carbon tetra-chloride (7.4) are lower than the corresponding values (10.6 and 8.8, respectively) for dithizone. The partition coefficient of the reagent is remarkably decreased in chloroform (270) and in carbon tetrachloride (160) due to the presence of fluorine atoms, compared to the corresponding values (10⁴.89 and 10⁴.18, respectively) for dithizone. The extraction constants of its complexes with Cd(II), Cu(II), Pb(II), Co(II), Hg(II), and Zn(II) were found to be higher than the corresponding values of dithizone complexes, thus enabling their extraction from more acidic solutions. The new reagent seems also to be slightly more sensitive for Bi(III), Cd(II), Co(II), Cu(II), and Hg(II).     

Reactive polymers, 47. Sorption properties of the reaction product of macroporous poly (glycidyl methacrylate-co-ethylene dimethacrylate) with 8-aminoquinoline

The sorption of Fe(III), Al(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Au(III), Pd(II), Pt(IV), and Hg(II) ions on a sorbent prepared by reacting the copolymer of glycidyl methacrylate and ethylene dimethacrylate with 8-aminoquinoline was investigated. Gold and palladium are strongly absorbed in hydrochloric acid. Results of static and dynamic tests indicate the possibility of separation of Au(III) and Pd(II) from Pt(IV) and from the other metal ions investigated in the study. The sorption of Hg(II) by the polymer increases in nitric acid.     

COMPARATIVE DISTRIBUTION COEFFICIENTS FOR SOME ELEMENTS WITH A MACROPOROUS CATION EXCHANGE RESIN IN HNO3 AND HCl

Cation exchange equilibrium distribution coefficients are presented for the chloride complex forming elements Hg(II), Bi(III), In, Cd, Pb(II), Fe(III), Ga, Zn, Cu(II) and Te{IV) with a macroporous (macroreticular) cation exchange resin in nitric acid of concentrations ranging from 0.20 to 5.00 M.Known distribution coefficients (from the literature) for similar concentrations of hydrochloric acid are included for comparative purposes and the influence of chloride complex formation is discussed. Separations which are possible by using both HC1 and HNO₃ as eluting agents are demonstrated by two elution curves separating the mixtures Hg(II)-Bi(III)-Zn-Pb(II); and Tl(III)-Bi(III)-Cu(II)-Fe(III).     

Foam Fractionation and Ion Flotation of Simple and Complex Anions with Cationic Surfactants

Experimental data are presented and interpreted on the foam fractionation of an extensive series of simple and complex anions from dilute (of the order 10⁻⁶−10⁻⁴ molar) aqueous solutions, utilizing a quaternary ammonium surfactant with which the anions form soluble ion pairs in competition with the surfactant's counterion. Selectivity coefficients, based on a bubble-interface, ion exchange model, are established in a single-equilibrium-stage, continuous-flow, foam fractionation unit for each of a series of 13 anions and oxyanions versus the surfactant's bromide counterion. Three additional series of batch experiments with multi-metal solutions establish the separation and concentration in the foam of the oxyanions of Re(VII), Mo(VI), Cr(VI), W(VI), and V(V); of the cyanide complex anions of Zn(II), Cd(II), Hg(II), and Au(III); and of the chloride complex anions of Zn(II), Cd(II), Hg(II), and Au(III). The metal oxyanions and metal cyanide and chloride complex anions can be separated from each other and from competing chloride, cyanide, or nitrate. Ion flotation of anionic species with a cationic surfactant involves an entirely different mechanism, in which a precipitation reaction occurs and particle flotation follows. Hexavalent chromium (primarily HCrO⁻₄) is ion-floated with each of a series of variable chain length quaternary ammonium surfactants, elucidating the effects of temperature, the surfactant/Cr(VI) feed ratio, mixing time, and surfactant chain length in terms of the roles of the surfactant as precipitant, dispersant, collector, and frother.     

Search for Optimum Conditions of Extraction of Transition Metal Complexes with Alkylimidazoles. I. Extraction of the Co(II), Ni(II), and Zn(II) Complexes of 1-Methylimidazole and of the Co(II) and Zn(II) Complexes of 2-Methylimidazole

Abstract

It has been shown that for the Co(II), Zn(II), and Ni(II) complexes of 1-methylimidazole and for the Co(II) and Zn(II) complexes of 2-methylimidazole, the partition coefficient D between the aqueous and organic phases is proportional to the degree of formation α _n of a definite complex. Tetrahedral species have been found to be extracted with the Co(II) and Zn(II) complexes of 2-methylimidazole and with the Zn(II) complexes of 1-methylimidazole.     

Ionic and Colloidal Flotation of 144Ce(lll) and 147Pm(lll)

Abstract

Ionic and colloidal flotation of ¹⁴⁴Ce(III) and ¹⁴⁷Pm(III) were studied on a laboratory scale from aqueous solutions with anion-active, cation-active, or non-ionic surface-active substances and the dependence on pH, on the concentration of the separated component, and on the surface-inactive electrolyte shown. In addition to separation in one stage, multistage separation was also used in order to achieve higher efficiency.     

The Effect of Degree of Impregnation in Amberlite Resins with Organophosphorous Extractants for Y(III), La(III), Ce(III), Th(IV) and U(VI) Ions

Abstract

Background: The sorption of Y(III), La(III), Ce(III), U(VI) and Th(IV) ions with solvent impregnated resins using diphenylphosphate (DPP), and diphenylphosphinic acid (DPPA) as extractant and Amberlite XAD 16 and Amberlite XAD 2000 as a polymeric support has been studied. The impregnated resins containing various amounts of extractants (10/90, 20/80, 50/50, 60/40) have been prepared by a dry method. The effects of pH, types of extractant, extractant content, surface area of polymeric support and contact time have been investigated by batch method.

Results: The impregnation for DPP on XAD‐16 and XAD‐2000 was 111 and 46% at 60/40 extractant/resin mass ratio, respectively. The impregnation of DPPA at all ratios on both resins was found constant and lower than DPP. The sorption percentage of studied metal ions was within 90‐99% for DPP and DPPA on both resins after 20/80 extractant/resin mass ratio.

Conclusions: The sorption of DPP on Amberlite XAD 16 and XAD 2000 resins is rather more than DPPA. It could be seen that 20/80 extractant/resin mass ratio is generally adequate for single metal analysis where 60/40 could be suitable for multi‐metal analysis.