Solvent extraction of metals using LIX26 extractant

Solvent extraction of some selected metals from an aqueous buffered solution by LIX26 extractant has been studied. The pH_1/2 values (at which 50% of metal ion is extracted) for extracting different metals by 1 v/v% LIX26 extractant in methyl isobutyl ketone have been obtained. The order of extraction of metals by LIX26 extractant as a function of pH_1/2 value is Pd(II)<Cu(II)<Sb(III)<Fe(II)<Co(II)<Zn(II)<Ni(II) <Pb(II)<Mn(II)<Cd(II).     

2-{[1-(3,4-Dihydroxyphenyl)methylidene]amino}benzoic acid immobilized Amberlite XAD-16 as metal extractant

2-{[1-(3,4-Dihydroxyphenyl)methylidene]amino}benzoic acid (DMABA) was loaded on Amberlite XAD-16 (AXAD-16) via azo linker and the resulting resin AXAD-16-DMABA explored for enrichment of Zn(II), Mn(II), Ni(II), Pb(II), Cd(II), Cu(II), Fe(III) and Co(II). The optimum pH values for extraction are 6.5-7.0, 5.0-6.0, 5.5-7.5, 5.0-6.5, 6.5-8.0, 5.5-7.0, 4.0-5.0 and 6.0-7.0, respectively. The sorption capacity was found between 97 and 515 μmol g⁻¹ and the preconcentration factors from 100 to 450. Tolerance limits for foreign species are reported. The kinetics of sorption is fast as t_1/2 is ≤5 min. The chelating resin can be reused for 50 cycles of sorption-desorption without any significant change (<1.5%) in the sorption capacity. The limit of detection values (blank +3 s) are 1.12, 1.38, 1.76, 0.67, 0.77, 2.52, 5.92 and 1.08 μg L⁻¹ for Zn(II), Mn(II), Ni(II), Pb(II), Cd(II), Cu(II), Fe(III) and Co(II), respectively. The enrichment on AXAD-16-DMABA coupled with monitoring by flame atomic absorption spectrometry (FAAS) is used to determine all the metal ion ions in river and synthetic water samples, Co in vitamin tablets and Zn in milk samples.     

Solvent extraction of several metal ions with mercaptotropone

Mercaptotropone was synthesized from tropone, and its acid dissociation constant (K_a) and distribution coefficient (K_D) between benze and aqueous solution were spectrophotometrically determined as 5.75 (pK_a) and 2.46 (log K_D); Extraction behaviour of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), Cr(III), Fe(III), Y(III), and Zr(IV) with this reagent into benzene was examined. Cu(II) and Fe(III) were completely extracted from acidic solution, Mn(II), Co(II), Ni(II), Zn(II), Pb(II), and Zr(IV) were also extracted from intermediate pH region, a part of Cr(III) was extracted, but Y(III) was not extracted.     

Determination of Metal Ions in Natural Waters by Flame-AAS after Preconcentration on a 5-Amino-1,3,4-Thiadiazole-2-Thiol Modified Silica Gel.

ABSTRACT

5-amino-1,3,4-thiadiazole-2-thiol groups attached on a silica gel surface have been used for adsorption of Cd(II), Co(II), Cu(II), Fe(III), Ni(II), Pb(II) and Zn(II) from aqueous solutions. The adsorption capacities for each metal ion were (in mmol.g^?1): Cd(II)= 0.35, Co(II)= 0.10, Cu(II)= 0.15, Fe(III)= 0.20, Hg(II)= 0.46, Ni(II)= 0.16, Pb(II)= 0.13 and Zn(II)= 0.15. The modified silica gel was applied in the preconcentration and quantification of trace level metal ions present in water samples (river, and bog water).     

Potentiometric Study of Tetracycline and Oxytetracycline with some Metal Ions of Biological Interest

Abstract

The stepwise metal-ligand stability constants of tetracycline and oxytetraoycline chelates with Mg(II), Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Cu(II), Zn(II), Zr(II) and Sn(II) have been determined using the Bjerrum-Calvin titration technique as employed by Irving and Rossotti. Protonation constant of the ligand and stability constants of the respective metal complexes have been determined at constant temperature (25°C) and ionic strength (0.1 M KCl). The general order of overall stability constant values have been found to be: Zr(IV) > Fe(III) > Co(II) > Zn(II) > Mg(II) > Mn(II) > Ni(II) > Sn(II) > Tn(II) > Cr(II). The rign values of the atability constanta are attricutel to the Ligands, which are stronger as an acid and weaser as a oase.     

4-{[(2-Hydroxyphenyl)imino]methyl}-1,2-benzenediol (HIMB) anchored Amberlite XAD-16: Preparation and applications as metal extractants

Amberlite XAD-16 was loaded with 4-{[(2-hydroxyphenyl)imino]methyl}-1,2-benzenediol (HIMB) via azo linker and the resulting resin AXAD-16-HIMB explored for enrichment of Zn(II), Mn(II), Ni(II), Pb(II), Cd(II), Cu(II), Fe(III) and Co(II) in the pH range 5.0-8.0. The sorption capacity was found between 56 and 415 μmol g⁻¹ and the preconcentration factors from 150 to 300. Tolerance limits for foreign species are reported. The kinetics of sorption is not slow, as t_1/2 is ≤15 min. The chelating resin can be reused for seventy cycles of sorption-desorption without any significant change (<2.0%) in the sorption capacity. The limit of detection values (blank + 3 s) are 1.72, 1.30, 2.56, 2.10, 0.44, 2.93, 2.45 and 3.23 μg l⁻¹ for Zn, Mn, Ni, Pb, Cd, Cu, Fe and Co, respectively. The enrichment on AXAD-16-HIMB coupled with flame atomic absorption spectrometry (FAAS) monitoring is used to determine the metal ion ions in river and synthetic water samples, Co in vitamin tablets and Zn in powdered milk samples.     

Flow Analysis of Transition Metals by Thermal Lensing

The conditions for the flow determination of Al(III), Bi(III), Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Nd(III), Ni(II), Pb(II), Pr(III), and Zn(II) by reaction with Xylenol Orange in aqueous solutions at pH 4.5 and the determination of Cd(II), Co(II), Cu(II), Fe(II), Ni(II), Pb(II), and Zn(II) by reaction with 4-(2-thiazolylazo)resorcinol in water–ethanol mixtures (5 : 1) at pH 5.0 using an injected sample volume of 80 L were proposed. The limits of detection were n × 10^–8–n × 10^–7 mol/L; the linearity ranges in the calibration graphs were of about three orders of magnitude; the relative standard deviation was of 3–7%.     

Metal Ions Uptake by Chelating Resin Derived from o-Substituted Benzoic Acid and its Synthesis,Characterization and Properties

Summary: Chelating resin [AFM] was synthesized by condensation of Anthranilic acid, Formaldehyde with m-Cresol. The chelating resin was characterized by FTIR Spectra, Elemental Analysis and SEM Photographs. The thermal behavior of the resin was characterized by TGA. The thermodynamic parameters such as Activation Energy (E_a), Order of decomposition (n), Entropy of decomposition (S*), Enthalpy (H*) and Free energy (G*) were calculated by Coats and Redfern method using TGA graph. The chelating behaviour of the prepared resin was studied out with using some metal ions [Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II)]. The sorption capacities of metal ions is found in the following order, Pb(II) < Zn(II) < Cd(II) < Cu(II) < Ni(II). The rate of half exchange was rapid t_1/2 < 20 min for lead ion. The separation of binary mixtures [Cu(II) and Zn(II) in brass and Pb(II) and Cd(II)] was successfully carried out using K_d value.     

Solid phase extractors derived by functionalising sub-micro silica gel with chelating agents and their pH-tunable adsorbing capability towards Pb(II) and Ag(I)

Three novel solid phase extraction agents were developed by functionalising sub-micron sized silica gel with organic functional moieties possessing {SN}-ligating atoms. The extractors were characterised by FTIR and TGA. Their capability of adsorbing the ions Fe(III), Cu(II), Zn(II), Cd(II), Cr(VI), Hg(II), Pb(II), Co(II), Ni(II), and Ag(I) is described. The extractors show pH-tunable selectivity for Ag(I) and/or Pb(II). By adjusting the pH to 5 or 6, high affinity is found for both Ag(I) and Pb(II), with little or no interference by the other metal ions. At pH values of <2, the extractors become highly selective for Ag(I), with an adsorption capacity of 35 mg g^?1. Little mechanical stirring is required due to the size of the particles. The recovery rates for both Ag(I) and Pb(II) were better 90% even after five repetitive adsorption-desorption cycles.     

Solvent extraction of copper(II), nickel(II), cobalt(II), zinc(II), and iron(Ill) by high molecular weight hydroxyoximes

The effects of pH have been examined on the extraction of the title ions by complexing with LIX-64N in kerosene. The extent of metal extraction as a function of pH is: Cu(II) < Fe(III) < Ni(II) < Zn(II) < Co(II). Stripping of all metal ions but cobalt with sulphuric acid from loaded kerosene complexing solutions is easily accomplished. Oxidation of Co(II) to Co(III) in the organic phase prevents stripping of this metal ion.     

Effect of the Nature of Crosslinking Agent on the Catalase‐Like Activity of Polystyrene‐Bound Glycine–Metal Complexes

Abstract

Catalase‐like activity of metal complexes of various crosslinked polystyrene‐supported glycines were carried out and correlated with the nature of crosslinking agent in the polymer support. Polystyrenes with 2 mol% divinyl benzene (DVB), ethylene glycol dimethacrylate (EGDMA), and 1,6‐hexanediol diacrylate (HDODA) crosslinking were used as polymer supports. Glycine functions were incorporated to the chloromethylpolystyrenes by polymer analogues reactions and complexed with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) ions. The metal uptake varied in the order: Cu(II) > Cr(III) > Mn(II) > Co(II) > Fe(III) > Ni(II) > Zn(II), and extent of metal uptake by various crosslinked systems varied with the nature of crosslinking agent. The polymeric ligands and the metal complexes were characterized by various analytical techniques. The catalytic activities of these metal complexes were investigated towards the decomposition of hydrogen peroxide and was found to decrease in the order: Co(II) > Cu(II) > Ni(II) > Cr(III) > Fe(III) > Mn(II) > Zn(II). With increasing rigidity of the crosslinking agent the catalytic activity also decreased.     

Capillary gas chromatographic analysis of pyrrolidinedithiocarbamate metal chelates

Pyrrolidinedithiocarbamate (PDTC) chelates of Zn(II), Cu(II), Ni(II), Co(III), Fe(III), Mn(II), Cr(III), and VO(II) were analysed by capillary GC on a DB-1701 column (30 m x 0.25 mm id) with flame ionisation detection (FID). Linear calibrations were attained within "1-30 microg/mL" for Ni(II), Fe(III), Mn(II), Cr(III), Cu(II), and VO(II), and within "2-50 microg/mL" for Co(III) and Zn(II). The limits of detection were in the "150-500 ng/mL" range, corresponding to 15-50 pg amounts reaching the FID system. The optimised method was applied to the determination of Cu(II) and Ni(II) in coins, and that of Zn(II), Cu(II), Ni(II), Fe(III), Mn(II), Cr(III), and VO(II) in pharmaceutical preparations with relative standard deviations within 1.1-5.2%. The results obtained are in good agreement with sewage water samples and the declared values for the pharmaceutical formulations, or with the results of AAS of metal contents in coins, pharmaceutical preparations, and sewage water samples.     

Organic acid solutions in the chromatography of inorganic ions VIII. Cation-exchange of Mn(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Fe(III), Sc(III), Y(III), Eu(III), Dy(III), Ho(III), Yb(III), Ti(IV) and Nb(V) in malate media

Summary The cation-exchange behaviour of Mn(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Fe(III), Sc(III), Y(III), Eu(III), Dy(III), Ho(III), Yb(III), Ti(IV) and Nb(V) in malate media at various concentrations and pH, was studied with Dowex 50 WX8 resin (200–400 mesh) in the ammonium form. Separation of Fe(III)/Cu(II), Fe(III)/Cu(II)/Zn(II), Fe(III)/Co(II)/Mn(II), Cu(II)/Ni(II)/Mn(II), Fe(III)/Cu(II)/Co(II)/Mn(II), Fe(III)/Cu(II)/Ni(II)/Cd(II), Yb(III)/Eu(III), Sc(III)/Y(III),Sc(III)/Yb(III)/Dy(III) and Nb(V)/Yb(III)/Ho(III) has been achieved, among others.This work was supported by C.N.R. of Italy.     

New sorbents and indicator powders for preconcentration and determination of trace metals in liquid samples

Two approaches to immobilize complex-forming analytical reagents (PAN, PAR, Xylenol orange, Brombenzothiazo, Crystal violet, Cadion, and Sulfochlorophenolazorhodanine) for the preparation of new sorbents and indicator powders are suggested: on-line coating of reversed-phase silica gel by reagents or doping of porous sol-gel silica with reagents. The retention of Ag, Cd, Cu(II), Co(II), Fe(III), Mn(II), Ni, Pb, and Zn on the sorbents developed was investigated. Quantitative sorption and desorption conditions were optimized. Procedures for the determination of Cd, Cu(II), Fe(III), Pb, and Zn with flame atomic absorption, spectrophotometric, and diffusion scattering spectrometric detection were elaborated. Detection limits for Cd, Cu(II), Fe(III), Pb, and Zn were 3 μg/L, 6 μg/L, 5 μg/L, 40 μg/L, and 1 μg/L, respectively. The procedures were used for the analysis of various real samples, e.g., natural and waste waters, and food. Received: 17 July 1997 / Revised: 20 January 1998 / Accepted: 5 February 1998     

Studies on tetrachlorodithizone isomers and their applications to the extraction of metal ions

Six isomeric tetrachlorodithizones were synthesized and their electronic and i.r. spectra were measured. Their acid dissociation constants and partition coefficients between 0.5 M NaClO₄ solution and carbon tetrachloride are reported. Their extraction equilibria with Cd(II). Co(II), Cu(II), Hg(II), Ni(II), Pb(II), Tl(I), Zn(II) and Bi(III) and the spectrophotometric characteristics of the complexes formed are described. The 3,3',4,4'-tetrachloro isomer is spectrophotometrically more sensitive than dithizone for Zn, Pb, Hg(II) and Bi(III) whereas the 2,2',3,3'- and 2,2',5,5'-isomers are more sensitive for copper ions. For most of the metals tested, the tetrachlorodithizones allowed quantitative extraction at lower pH than is possible with dithizone.     

Beiträge zur Ringofenmethodik. XV

Microchimica Acta - Ein Trennungsschema für Cs(I), Ag(I), Ba(II), Zn(II), Cd (II), Mn(II), Pb(II), Cu(II), Ni(II), Co(II), Bi(III), Al(III) und Fe(III) unter Verwendung von Dithiooxamid als...     

Determination of Metal Ions by High Performance Liquid Chromatography

The mixture of metal ions [Bi(III), Fe(III), Fe(II), Cu(II), Zn(II), Ni(II), Co(II), Pb(II), Cd(II), Mn(II)] were separated in the bonded-phase strong cation exchange column (Vydac-401 SA) and monitored at 540 nm after a postcolumn reaction with 4-(2-pyridylazo)-resorcinol (PAR). Citrate, tartrate, lactate and α-hydroxyisobutyrate buffer were used as eluent and it has been found that the elution order of some metal ions were changed with different eluents. The detection limits and the calibration curves of metal ions were also studied.     

Preparation, characterization and metal sorption studies of a Chrome-Azurol-S-loaded anion-exchange resin

Chrome Azurol S (CS) was mobilized on an strongly basic anion-exchange resin (Dowex 2 x 4, in Cl(-) form) by batch equilibration. The modified resin was stable in acetate buffer solution and in 0.1 M HCl and H(2)SO(4), but it was readily degraded with 2-6 M HCl and HNO(3). Retention of Ba(II), Sr(II), Ca(II), Mg(II), Al(III), Cr(III), Zn(II), Fe(III), Ti(IV), Mn(II), Co(II), Ni(II), Cu(II), Cd(II) and Pb(II) was studied using the batch equilibration method. The uptake and recovery yields were determined by using inductively-coupled plasma atomic emission spectroscopy (for Mg, Al, Cr, Ti, Fe, Mn, Ni, Zn, Cu, Cd and Pb) and atomic absorption spectrophotometry (for Ba, Sr, Ca and Co). The optimum pH value was established for performing a selective separation of Al(III) from the other metal ions. The sorption capacities of the CS-loaded resing for Al(III), Cr(III), Mg(II) (at pH 6), Fe(III) (at pH 5) and Ti(IV) (at pH 4) were 14, 2.9, 0.3, 3 and 3.9 mumoles g(-1) respectively. On this basis a method for separating Al(III) from other cations was established.     

Solid phase extraction of metal ions using carbon nanotubes

The sorption behaviour of carbon nanotubes (CNTs) toward some divalent metal ions such as Cu(II), Co(II), Ni(II), Zn(II), Pb(II), Mn(II) and Cd(II) has been investigated systematically. The affinity order of the metal ions towards CNTs at pH in the range of 7.0-9.0 was: Cu(II) > Pb(II) > Zn(II) > Co(II) > Ni(II) > Cd(II) > Mn(II). The experimental parameters for preconcentration of copper, which exhibits the highest affinity towards carbon nanotubes, on a microcolumn packed with CNTs prior to its determination by flame atomic absorption spectrometry have been investigated. Copper can be quantitatively retained at pH 8.2 from sample volume up to 150 mL and then eluted completely with 0.1 mol L^− 1 HNO₃. The limit of detection limit for Cu(II) determination with FAAS detection was 2.1 μg L^− 1, and the RSD was 3.5% at the 50 μg L^− 1 level. Under the optimal conditions for copper enrichment also Zn(II), Pb(II) and Ni(II) could be quantitatively preconcentrated from water samples. The method was validated using a certified reference materials BCR-610 and SRM 1640.     

Use of dichloromethane with dithizone as an alternative solvent to carbon tetrachloride restricted by Montreal protocol

The spectral characteristics of dithizone and its metal complexes were measured in dichloromethane as an alternative solvent to carbon tetrachloride which will be illegal to manufacture by the year 2000, according to the revised Montreal Protocol. The extraction equilibria of its metal complexes were also reported and discussed. Dichloromethane was found to enhance the sensitivity of dithizone towards Co(II), Cu(II), Hg(II), Pb(II), Zn(II), Bi(III), Ag(I), In(III) and Tl(I). It was also found to be a better solvent than carbon tetrachloride for the separation of Cd(II) from Zn(II) and for the separation of Co(II) from Ni(II).