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).     

Emulsion liquid membrane extraction of Ni(II) and Co(II) from acidic chloride solutions using bis-(2-ethylhexyl) phosphoric acid as extractant

An emulsion liquid membrane process using bis-(2-ethylhexyl) phosphoric acid (D2EHPA) to extract and separate Ni(II) and Co(II) from acidic chloride solutions is described. Liquid membrane consists of a diluent, a surfactant (Span 80), and an extractant (D2EHPA). Hydrochloric acid was used as the stripping solution. The important parameters governing the permeation of nickel and their effect on the separation process have been studied. These parameters are stirring speed, feed phase pH, surfactant concentration, extractant concentration, stripping phase concentration, phase ratio, initial concentration of metal, and treatment ratio. The optimum conditions have been determined. The separation factors of Ni(II) with respect to Co(II), based on initial feed concentration, have been experimentally determined. Furthermore, the extraction selectivity for Co(II) over Ni(II) has been improved by using D2EHPA during the initial minutes.     

A dinuclear Ni(II) complex with two types of intramolecular magnetic couplings: Ni(II)-Ni(II) and Ni(II)-TTF*+

A dinuclear Ni(II) complex involving tetrathiafulvalene (TTF) radicals as ligands has been prepared and characterized, [Ni2(mu-Cl)2(L*+)2(I3)4(I2)3.(H2O)2.(C4H8O)3 (1), L = 4,5-bis(2-pyridylmethylsulfanyl)-4',5'-ethylenedithiotetrathiafulvalene. There are two types of intramolecular magnetic exchange interactions, namely one ferromagnetic Ni(II)-Ni(II) and one antiferromagnetic Ni(II)-TTF*+. This study is new in the respect of revealing a magnetic exchange interaction between a TTF*+ radical and a paramagnetic transition metal ion. This is due to the fact of a direct binding of the transition metal ion to the skeleton of the TTF*+ radical.     

Extraction and separation of mercury(II) using triisobutyl phosphine sulfide (TIBPS/Cyanex) as an extractant and its application to industrial effluent

Studies have been carried out on the extraction of Hg(II) along with Cr(III), Fe(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II) and Ag(I), from mineral acid media using TIBPS. The effect of different variables influencing extraction of Hg(II), such as, mineral acid used, nature of diluent, concentration of metal ion and extractant has been investigated. Based on the partition data some binary separations from Hg(II) have been achieved. The potential of the extractant for decontaminating Hg from paper industry effluent has been assessed.     

Performance Evaluation of Nickel Separation and Extraction Process from Simulated Spent Cr/Ni Electroplating Bath Solutions by ELM Process Using LIX63 and PC88A

The study was conducted to investigate synergistic extraction of nickel from simulated spent Cr–Ni electroplating bath solutions by emulsion liquid membrane (ELM) process using 5,8-diethyl-7-hydroxydodecan-6-one oxime (LIX 63) and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC88A) as carriers. The importance of ELM composition and the properties of simulated spent electroplating bath solution have been optimized to synergistically extract nickel. The important parameters affecting the nickel extraction efficiency and ELM stability, such as acid concentration, stripping solution type and concentration, extractant concentration, surfactant concentration, and phase ratio, were experimentally studied. Along with obtained results, higher than 99% of nickel was selectively extracted within 30 minutes from simulated electroplating bath solutions that their metal concentrations was in the range of 100–500 mg/L. in the optimum conditions. The higher separation factor value of nickel over chromium (β_Ni/Cr) was obtained as 898. As a result, the nickel extraction kinetic was found to depend on PC88A, since extraction mechanism of PC88A is slower than that of LIX63. So, the combined use of LIX63 and PC88A improved the selective extraction of nickel in that process.     

A study of the complexation and extraction of Cu(II) sulfate and Ni(II) sulfate by N3O2-donor macrocycles

Comparative solvent extraction (water/chloroform) studies of Ni(II) and Cu(II) employing a dinonyl-substituted N3O2-donor macrocycle (L2) as extractant have been undertaken from sulfate, chloride, nitrate and acetate-containing aqueous media. Contrary to expectations, efficient extraction of both metal sulfates was observed, the degree of extraction being comparable (or slightly enhanced) relative to that observed for each of the other anionic systems. X-Ray diffraction studies of [NiL1(H2O)3]SO4 x 4H2O and [CuL1(H2O)]SO4 x 6.67 H2O (where L1 is the unsubstituted derivative of L2) show that each complex occurs as a hydrogen-bonded 'cluster', with the sulfate anions involved in hydrogen bonded networks that incorporate ligand amine protons and water molecules; in the copper complex, which adopts a dimeric arrangement, simultaneous sulfate binding to a copper site is also present. In each complex the macrocyclic ligand fails to coordinate via its ether oxygen donors but instead is arranged so that the metal ion and sulfate anions are somewhat shielded hydrophobically from the exterior of the complex cluster assembly.     

Solvent extraction of metals with commercial oxime extractant (LIX 622)

The extraction characteristics of some selected metals from an aqueous buffered solution by LIX 622, a commercial oxime extractant have been studied. The pH_1/2 values for extracting different metals with 5 v/v% LIX 622 extractant in methyl isobutyl ketone (MIBK) have been obtained. The order of extraction of metals with LIX 622 extractant as a function of pH_1/2 value is determined and results agree well with the order obtained using salicylaldoxime as chelating ligand for the extraction of these metals.     

Solid phase extraction of lead (II), copper (II), cadmium (II) and nickel (II) using gallic acid-modified silica gel prior to determination by flame atomic absorption spectrometry

The immobilization of gallic acid on the surface of amino group-containing silica gel phases for the formation of a newly chelating matrix (GASG) is described. The newly synthesized extractant, characterized by the diffuse reflectance infrared Fourier transformation spectroscopy and elemental analysis, was used to preconcentrate Pb(II), Cu(II), Cd(II) and Ni(II). The pH ranges for quantitative sorption and the concentrations of HCl for eluting Pb(II), Cd(II), Cu(II) and Ni(II) were opimized, respectively. The sorption capacity of the matrix has been found to be 12.63, 6.09, 15.38, 4.62mg/g for Pb(II), Cd(II), Cu(II) and Ni(II), respectively, with the preconcentration factor of approximately 200 ( approximately 100 for Cd(II)). The effects of flow rates, the eluants, the electrolytes and cations on the metal ions extraction, as well as the chelating matrix stability and reusability, were also studied. The extraction behavior of the matrix was conformed with Langmuir's equation. The present preconcentration and determination method was successfully applied to the analysis of synthetic metal mixture solution and river water samples. The 3sigma detection limit and 10sigma quantification limit for Pb(II), Cu(II), Cd(II) and Ni(II) were found to be 0.58, 0.86, 0.65, 0.92microg/L and 1.08, 1.23, 0.87, 1.26microg/L, respectively.     

Chemically modified silica gel with aminothioamidoanthraquinone for solid phase extraction and preconcentration of Pb(II), Cu(II), Ni(II), Co(II) and Cd(II)

Silica gel chemically bonded with aminothioamidoanthraquinone was synthesized and characterized. The metal sorption properties of modified silica were studied towards Pb(II), Cu(II), Ni(II), Co(II) and Cd(II). The determination of metal ions was carried out on FAAS. For batch method, the optimum pH ranges for Pb(II), Cu(II) and Cd(II) extraction were ≥3 but for Ni(II) and Co(II) extraction were ≥4. The contact times to reach the equilibrium were less than 10 min. The adsorption isotherm fitted the Langmuir's model showed the maximum sorption capacities of 0.56, 0.30, 0.15, 0.12 and 0.067 mmol/g for Pb(II), Cu(II), Ni(II), Co(II) and Cd(II), respectively. In the flow system, a column packed modified silica at 20 mg for Pb(II) and Cu(II), 50 mg for Cd(II), 60 mg for Co(II), Ni(II) was studied at a flow rate of 4 and 2.5 mL/min for Ni(II). The sorbed metals were quantitatively eluted by 1% HNO₃. No interference from Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻ and SO₄²⁻ at 10, 100 and 1000 mg/L was observed. The application of this modified silica gel to preconcentration of pond water, tap water and drinking water gave high accuracy and precision (%R.S.D. ≤ 9). The method detection limits were 22.5, 1.0, 2.9, 0.95, 1.1 μg/L for Pb(II), Cu(II), Ni(II), Co(II) and Cd(II), respectively.     

Reactivity of potassium tetracyanomercurate with Ag(I), Ni(II) And Co(II)

Potentiometric and conductometric studies on the reactions between K(2)Hg(CN)(4) and Ag(I), Ni(II), Co(II) are reported. The possibility of determination of these metal ions has been evaluated and some titration data are reported.     

Extraction of Copper(II) and Zinc(II) from Chloride Media with Mixed Extractants

Extraction of copper(II) and zinc(II) from acidic chloride solutions with mixtures of two extractants: a basic or solvating one and a chelating extractant was discussed. Processes for recovery and separation of Cu(II) from Zn(II) were proposed, which consist of the following steps: extraction from chloride media with the formation of metal chlorocomplex ion pair or solvate, scrubbing of chloride ions with an aqueous solution of appropriate pH with simultaneous transfer of the metal ion to the chelate, traditional stripping with sulphuric acid and conditioning of the basic extractant. Both effective recovery and separation of metal ions with simultaneous change of the system from the chloride to the sulphate state can be achieved. A bifunctional reagent, such as alkyl derivative of 8-hydroxyquinoline, can be also used instead of the extractant mixture.     

Two-phase potentiometric metal extraction titrations of silver(I), copper(II) and cadmium(II) using some cation-exchangers as extractants

The use of two-phase potentiometric metal extraction titrations to study solvent extraction equilibria is described. The method provides a highly reproducible and convenient manner by which to determine extraction behaviour. The system was tested on a number of acidic extractants, namely D2EHPA, Ionquest 801, Cyanex 272, naphthenic acid and Versatic 10 acid. The extraction from an aqueous nitrate medium of silver(I), copper(II) and cadmium(II) was studied. The potentiometric data were used to obtain extraction curves and elucidate the nature of the extracted complexes by slope analysis and non-linear least squares treatment. In general, the following extraction order was obtained: D2EHPA > Ionquest 801 > Cyanex 272 and naphthenic > Versatic 10 for copper(II) and cadmium(II). Organophosphorus acids were shown to form complexes of the nature of Cu(HA(2))(2) with copper(II) and carboxylic acids formed dimeric complexes (CuA(2)(HA))(2). With cadmium octahedral complexes of the form CdA(2)(HA)(4) occurred. The extraction of silver(I) by Versatic 10 gave a dimeric complex (AgA(HA))(2). HA denotes the extractant in the acid form.     

Study of the kinetics of the transport of Cu(II), Cd(II) and Ni(II) ions through a liquid membrane

The coupled transport of Cu(II), Cd(II) and Ni(II) ions through a bulk liquid membrane (BLM) containing pyridine-2-acetaldehyde benzoylhydrazone (2-APBH) as carrier dissolved in toluene has been studied. Once the optimal conditions of extraction of each metal were established, a comparative study of the transport kinetics for these metals was performed by means of a kinetic model involving two consecutive irreversible first-order reactions. The kinetic parameters (apparent rate constants of the metal extraction and re-extraction reactions (k ₁, k ₂), the maximum reduced concentration of the metal in the liquid membrane (), the time of the maximum value of R _o ( t _max) and the maximum entry and exit fluxes of the metal through the liquid membrane ( and ) of the extraction and stripping reactions were evaluated and results showed good agreement between experimental data and theoretical predictions. Complete transport through the membrane took place according to the following order: Cd(II)>Cu(II)>Ni(II), with similar kinetic parameters obtained for Cu(II) and Cd(III). The transport behaviour of Ni(II) was different to that of Cu(II) and Cd(III), probably due to the different stoichiometry of the nickel complex compared to those of the other metal ions and the different chemical conditions required for its formation. The influence of the sample salinity on the transport kinetics was studied. k ₁ values decreased slightly when the feed solution salinity was increased for Cu(II) and Ni(II), but not for Cd(II). Values of k ₂ were practically unaffected. The proposed BLM was applied to the preconcentration and separation of metal ions (prior to their determination) in water samples with different saline matrices (CRM, river water and seawater), and good agreement with the certified values was obtained.     

Sulfonamide mit heterocyclischen Substituenten als Extraktionsmittel für Kupfer(II)

Sulfonamides with Heterocyclic Substituents as Extractants for Copper(II) With 2-picolylbenzenesulfonamide (N2NHO₂SC₆H₅) as a model of the technical extractant LIX 34, the influence of functional variations on the extraction of copper(II) is studied and estimated by a comparison of the pH_1/2 values. The relation pH_1/2～–σ_p is observed for extractants with substituents in p-position of the benzene ring. Turning to 2-pyridylethylbenzenesulfonamide, which forms six-membered rings, an increase of pH_1/2 is observed. But no direct comparison is possible with 2-pyridylbenzenesulfonamide as the copper(II) complexes are dimeric having a structure analogous to copper(II) acetate. The substitution of the methylene group by an SO₂–(PSA? H) or an NH-residue (PTSH? H) is connected with an with an increase of pH_1/2 in the first case, but a decrease of pH_1/2 in the second one (7,2₅ and 2,7₀). The application of PTSH? H as an extractant for copper(II) is confined by a slow redox reaction with this ion. π-electron delocalization within the chelate rings, which are derived from sulfonylhydrazones of heterocyclic ketones, is a factor which, in general, improves the extraction properties. There is a strong differentiation of PH_1/2 (APSH? H 1,4; BBSH? H 6,9). An increase of the tetrahedral distortion of the chromophore CuN₄, as it is indicated by ESR, measurements, is connected with a decrease of pH_1/2. The benzenesulfonyl group influences the copper(II) extraction by bidentate nitrogen containing ligands in a twofold may: The protonation of the pyridyl and also that of other heterocyclic residues is rendered more difficult, but NH-acidity is increased. Some of the new extractants (APSH? H, BPSH? H) are as active as LIX reagents.     

The synthesis of (N2O2S2)-Schiff base ligands and investigation of their ion extraction capability from aqueous media

Two new Schiff bases (I) and (II) containing nitrogen-sulfur-oxygen donor atoms were designed and synthesized in a multi-step reaction sequence. The Schiff base (I) was used in solvent extraction of metal chlorides such as Cu2+ and Cr3+ as well as metal picrates such as Hg2+ and UO2(2+) from aqueous phase to the organic phase. The influences of the parameter functions, such as pH, solvent, ionic strength of aqueous phase, aqueous to organic phase and concentration of the extractant were investigated to shed light on their chemical extracting properties upon the extractability of metal ions. The effect of chloroform, dichloromethane and nitrobenzene as organic solvents over the metal chlorides extraction was investigated at 25±0.1 °C by using flame atomic absorption and the result is that the ability of extraction in solvents as follows: C6H5NO2>CHCl3>CH2Cl2 and the compositions of the extracted species have been determined. The metal picrate extraction was investigated at 25±0.1 °C by using UV-visible spectrometry. As well that the extraction of picrates metal such as UO2(2+) and Hg2+ with Schiff base(I) in absence and presence of 2-(2-aminoethyl) pyridine was investigated in chloroform. The extraction results revealed the presence of neutral donors 2-(2-aminoethyl) pyridine shifts the extraction percentage curves towards higher pH region, indicating a synergistic effect of this donors on extraction of UO2(2+) and Hg2+ by the studied Schiff base (I).     

Ferro- and antiferromagnetic interactions in face-sharing trioctahedral Ni(II)Mn(II)Ni(II) and Ni(II)Fe(III)Ni(II) complexes with the same 1-5/2-1 spin system

Two heterotrinuclear complexes, [Mn(II)(Ni(II)L)2].2CH3OH (where H3L = 1,1,1-tris(N-salicylideneaminomethyl)ethane) and [Fe(III)(Ni(II)L)2]NO3.C2H5OH, consisting of three face-sharing octahedra have been prepared; although these complexes have closely related structures and have the same 1-5/2-1 spin system, they show completely different magnetic interactions between the adjacent metal ions: ferromagnetic (Ni(II)-Mn(II)) and antiferromagnetic (Ni(II)-Fe(III)).     

Formation of Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Ag(I) and Cd(II) hexacyanocobaltates

A study is reported of the formation of Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Ag(I) and Cd(II) hexacyanocobaltates. The results show that the precipitates form by reaction of the metal ions with KCo(CN)(6)(2-) ion-pairs in 1:1 ratio, followed by solid phase transformations.     

Ni(III) vs. Ni(II)-thiyl radical: charge-delocalisation in a binuclear Ni(III)Ni(II)-dithiolate complex

Multi-frequency EPR spectroscopy on 61Ni-labelled samples of [Ni2(L)]3+ confirms extensive charge-delocalisation between the Ni(III) centre and thiolate donors in the Ni(II)Ni(III) complex.