Evaluation of the toluene-3,4-dithiol (TDT)-trioctylamine (TOA) synergic extraction system

Synergic extraction of different essential and toxic metal ions such as Mn(II), Co(II), Zn(II), Hg(II), Cd(II) and Se(IV) has been carried out using toluene-3,4-dithiol (TDT) and trioctylamine (TOA) in chloroform. A strong synergic effect in the extraction of Co(II), Mn(II) and Zn(II) has been observed. The effect of different anions on the extraction has also been analyzed. Ascorbate ions can easily separate Hg(II) and Se(IV) ions. The stability of synergic adduct and reaction mechanism are discussed.     

Sulphuric acid influence on liquid-liquid extraction of Co(II) and Zn(II) by MIBK from NH(4)SCN medium

Liquid-liquid extraction of Co(II) and Zn(II) by methylisobutylcetone (MIBK) has been studied systematically from NH(4)SCN/H(2)SO(4) media. The influence of sulphuric acid concentration on the percentage of extraction of Co(II) and Zn(II) has been discussed. It is shown that sulphuric acid concentration has not the same effect on distribution curves of Co(II) and Zn(II). Thus, it is possible to have a separation of Zn(II) of Co(II) when [NH(4)SCN] is 0.5 mol l(-1) and [H(2)SO(4)] is about 2 mol l(-1). Under these conditions the separation factor (S(Zn/Co)) is around 580. The results are treated in terms of thermodynamic activities in aqueous phase, to determine the composition of the extracted complexes (M:SCN(-)) and to discuss the extraction mechanism.     

The separation of zinc(II) and cadmium(II) by liquid-liquid extraction

The extraction of Zn(II) and Cd(II) from thiocyanate solutions with bis-2-ethylhexyl sulphoxide (B₂EHSO) in benzene as an extractant has been studied by tracer techniques. For comparison, extraction has also been carried out with tributylphosphate (TBP). The extraction data have been analysed by both graphical and theoretical methods by taking into account complexation of the metal in the aqueous phase by inorganic ligands and plausible complexes extracted into the organic phase. The results demonstrate that Zn(II) is extracted as Zn(SCN)₂·2B2EHSO and Zn(SCN)₂·2TBP. In the case of Cd(II), the extracted species are Cd(SCN)₂·4B2EHSO/4TBP. The synergistic extraction of Zn(II) and Cd(II) with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and B2EHSO or TBP or trioctylphosphine oxide (TOPO) from acetate buffer solutions has also been investigated. Zn(II) is extracted as Zn(PMBP)₂·B2EHSO/TBP/TOPO. On the other hand, Cd(II) is found to be not extracted with these mixed-ligand systems under the experimental conditions. These results also demonstrate the mutual separation of Zn(II) and Cd(II) using the synergistic extraction with HPMBP in the presence of various neutral oxodonors.     

Solvent extraction of metals with potassium-dihydro-bispyrazolyl-borate

The extraction of Cu(II), Ni(II), Co(II), Cd(II), Zn(II), Pb(II) and Mn(II) with potassium-dihydro-bispyrazolyl-borate (H(2)BPz(2)(-)) in dichloromethane has been studied. Extraction constants (logK(ex)) have been calculated for all metal systems and were compared with those obtained with dibenzoylmethane (DBM), thenoyltrifluoroacetone (HTTA) and 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP). The method has been used for the determination of Cu(II), Co(II), Cd(II), Zn(II), Pb(II) and Mn(II) in standard alloys and for preconcentration of metal ions in synthetic samples.     

Determination of Nickel in Biological Samples by Electrothermal Atomization-Atomic Absorption Spectrometry Involving a Prior Extraction with 1,5-Bis (Di-2-Pyridylmethylene) Thiocarbono-Hydrazide

Abstract

The use of 1,5-bis(di-2-pyridylmethylene) thiocarbono-hydrazide as a reagent for the extraction of Ni(II), Co(II), Zn(II), Fe(II), Cd(II) and Cu(II) into methyl isobutyl ketone has been studied, and a method for the determination of nickel at ultra-trace (ng/ml) level has been developed, by using electrothermal-atomization (graphite furnace) atomic absorption spectrometry involving a prior extraction with the cited extracting reagent. The chief advantage of the proposed method lies in its maximum allowed aqueous-to-organic phase volume ratio of 15. It has been successfully applied to the determination of nickel substrates in various biological samples.     

Solvent extraction of Zn/II/ with 1,2,3-benzotriazole into n-hepatanol

A method based on solvent extraction has been developed for the radiochemical separation of Zn/II/ from other elements employing 1,2,3-benzotriazole as a complexing agent and n-heptanol as an extractant. Optimum conditions for the extraction have been established. The effect of various anions and cations on the extraction coefficient value of Zn/II/ has been studied. The stoichiometry of the metal to reagent determined by the method of substoichiometric extraction and slope-ratio method was found to be 12.     

Determination of gold by substoichiometric extraction with N-thioacetyl benzamide

Estimation of gold has been successfully carried out by substoichiometric radiochemical solvent extraction method using a newly designed organic moiety, N-thioacetyl benzamide as extractant and chloroform as solvent at aqueous pH 4. The interference effects of different closely related diverse ions like Fe(III), Cu(II), Co(II), Zn(II), Ni(II) etc. were also critically studied. The validity of this method has been verified by the study of recovery of gold in mud samples.     

Die Extraktion und Trennung von Mikromengen Quecksilber(II), Zink(II) und Cadmium(II) mit organischen Thiophosphorverbindungen

Zusammenfassung Die Extraktion von Zink(II), Cadmium(II) und Quecksilber(II) aus salzsauren und salpetersauren Lösungen mit Di-n-butylthiophosphit und Di-n-butyl-2-hydroxypropylthiophosphonat wurde studiert. Die Abhängigkeit der Verteilung der Metalle von der Säurekonzentration und der Konzentration der Liganden wurde festgestellt. Eine neue Trennungsmethode für Mikromengen Quecksilber durch Extraktion mit Di-n-butylthiophosphit wurde entwickelt.

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The extraction and separation of micro amounts of Hg(II) from Zn(II) and Cd(II) by means of thiophosphoric compounds

Summary The extraction of zinc(II), cadmium(II) and mercury(II) from hydrochloric and nitric acid solutions has been studied with di-n-butyl thiophosphite and di-n-butyl 2-hydroxypropyl thiophosphonate. The dependence of the extraction of the metals on the acid and ligand concentrations has been established. A new separation method for micro amounts of mercury has been developed.

     

Cloud Point Extraction Simultaneous Spectrophotometric Determination of Zn(II), Co(II) and Ni(II) in Water and Urine Samples by 1-(2-Pyridylazo)2-Naphthol Using Partial Least Squares Regression

A cloud-point extraction (CPE) process using the nonionic surfactant Triton X-114 to simultaneous extraction and spectrophotometric determination of Zn(II), Co(II) and Ni(II) from aqueous solution using partial least squares (PLS) regression is investigated. The method is based on the color reaction of these cations with 1-(2-pyridylazo)2-naphthol and subsequent micelle-mediated extraction of products. The optimum extraction and reaction conditions such as pH, reagents concentration and effect of time have been studied. Linearity was obeyed in the range 2–150, 5–250 and 2–150 ng mL⁻¹ of Zn(II), Co(II) and Ni(II) respectively. The relative standard error (RSE) for the simultaneous determination of 15 test samples of different concentrations of Zn(II), Co(II) and Ni(II) was 4.38%;, 1.18% and 2.42%, respectively. The total relative standard error (RSE_t) for applying the PLS method to 15 synthetic samples in the linear ranges of these metals was 2.36%. The interference effect of some anions and cations was also tested. The method was applied to the simultaneous determination of Zn(II), Co(II) and Ni(II) in water and human urine samples.     

Liquid-liquid extraction of zinc(II) as its ethyl xanthate

A method for quantitative extraction of zinc with potassium ethyl xanthate into carbon tetrachloride is described. The optimum conditions are: pH 5-6 and Zn(II) to reagent ~1:8 mole ratio. The effects of other ions on the extraction of Zn(2+) have been investigated, and its separation from As(3+), Pb(2+), Cu(2+) and Fe(3+)is described. The possibility of repeated use of the solvent (still loaded with xanthate after the zinc has been stripped) for further extractions (after addition of a little extra xanthate) has been explored. Various stripping agents have been examined, and the optimum conditions found.     

Solvent extraction of zinc by 2-hexylpyridine in benzene from aqueous mineral acid — Thiocyanate media

Solvent extraction of Zn(II) by 2-hexylpyridine (HPy) in benzene has been studied from aqueous mineral acid—thiocyanate media. The extraction, though dependent on the acidity of the aqueous phase, is poor from mineral acids (HCl, HNO₃ or H₂SO₄). Addition of 0.02M KSCN to the aqueous phase enhances the distribution ratio by a factor of almost one thousand. The stoichiometry of the extracted complex established by the usual slope analysis method indicates that an ionic type complex, e.g. Zn(SCN)₄·(HPyH)₂, is responsible for extraction. Complexing anions like acetate, oxalate or citrate at 1 M concentration mask the extraction of Zn(II) almost completely. Separation factors determined at optimal conditions (0.1M HPy in benzene −0.05M H₂SO₄+0.2M SCN⁻) indicate that Zn(II), along with Hg(II), can be separated in a single extraction from a number of metals, e.g. Cs(I), Sr(II), Ln(III), Y(III), Cr(III) and (VI). Other metals of interest like Cu(II), Co(II), Fe(III), Mo(VI), U(VI) and Tc(VII) are coextracted but the separation factors are large enough to allow separation in a multistage extraction process.     

Selective separation of copper with Lix 864 in a hollow fiber module

The transfer and separation of Cu(II), Co(II), Ni(II) and Zn(II) ions across a hollow fiber supported liquid membrane containing LIX 864 as the mobile carrier dissolved in kerosene solvent has been investigated. The flux and selectivity for copper has been studied as a function of the feed flow, the carrier concentration in the liquid membrane and the extraction solution acidity. A maximum copper recovery at 30% of LIX (v/v) in the diluent was obtained. The permeation experiments showed that at pH 2 in the extraction solution a highly selective separation of Cu over the other cations can be achieved. Increasing the acidity of the extraction solution copper selectivity decrease and the grade of recuperation sequence is Cu>Co>Ni>Zn. These results suggest that in selected situations, this membrane system can be competitive with the conventional liquid-liquid extraction process, in particular in leaching solutions with low metal concentration.     

Equilibrium and kinetics of Zn(II) bromide extraction with Amberlite LA-2 and methyl isobutyl ketone

The rates of extraction of Zn(II) from hydrobromic acid solutions into benzene solutions of the liquid anion exchanger Amberlite LA-2 and those into methyl isobutyl ketone (MIBK) have been investigated. The distribution equilibria of this system have been also studied. Under the used experimental conditions the extracted species of Zn(II) have been proposed. The kinetic data indicated a first order reaction with respect to Zn(II) in both systems, nearly one with respect to HBr and from 0–0.38 for LA-2. In case of extraction of Zn(II) with methyl isobutyl ketone, MIBK, the reaction order with respect to MIBK was found to be 4 and with respect to HBr inverse first order. The rate constants of these extraction processes were determined and the rate determining steps were discussed in the light of the obtained results.     

Enhancement effect of 3,5-dichlorophenol on the solvent extraction of copper(II) and zinc(II) with acetylacetone and trifluoroacetylacetone

The effect of 3,5-dichlorophenol (DCP) on the extraction of Cu(II) and Zn(II) with acetylacetone (Hacac) and trifluoroacetylacetone (Htfa) in heptane and carbon tetrachloride has been investigated. DCP enhances these chelate extractions; the largest effect is observed on the extraction of Cu(II) with Hacac, which is much larger than the corresponding synergistic effect seen with neutral electron donors such as trioctylphosphine oxide. By analysing the various equilibria involved, the enhanced extraction has been ascribed to the formation of association complexes of the bis(beta-diketonato) chelates (MA(2)) with DCP as MA(2).nDCP (n = 1 for A = tfa and n = 2 for A = acac) in the organic phase, and the association constants have been determined. The association constants increase in the following order of ligand and metal(II): tfa < acac and Zn(II) < Cu(II). These orders are exactly opposite those observed in the adduct formation of the chelates with neutral electron donors.     

Silica gel surface modified with sulfanilamide for selective solid-phase extraction of Cu(II), Zn(II) and Ni(II)

A new chelating matrix has been prepared by immobilising sulfanilamide (SA) on silica gel (SG) surface modified with 3-chloropropyltrimethoxysilane as a sorbent for the solid-phase extraction (SPE) Cu(II), Zn(II) and Ni(II). The determination of metal ions in aqueous solutions was carried out by inductively coupled plasma optical emission spectrometry (ICP-OES). Experimental conditions for effective sorption of trace levels of Cu(II), Zn(II) and Ni(II) were optimised with respect to different experimental parameters using the batch and column procedures. The presence of common coexisting ions does not affect the sorption capacities. The maximum sorption capacity of the sorbent at optimum conditions was found to be 34.91, 19.07 and 23.62 mg g^?1 for Cu(II), Zn(II) and Ni(II), respectively. The detection limit of the method defined by IUPAC was found to be 1.60, 0.50 and 0.61 µg L^?1 for Cu(II), Zn(II) and Ni(II), respectively. The relative standard deviation (RSD) of the method under optimum conditions was 4.0% (n = 8). The method was applied to the recovery of Cu(II), Zn(II) and Ni(II) from the certified reference material (GBW 08301, river sediment) and to the simultaneous determination of these cations in different water samples with satisfactory results.     

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.     

Ionic strength effect on the liquid–liquid extraction of zinc(II) and cadmium(II) from sulphate medium by 1-phenyl-3-methyl-4-benzoylpyrazol-5-one in chloroform

The liquid–liquid extraction of zinc(II) and cadmium(II) from sulphate medium by 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (HPMBP) in chloroform is studied. The ionic strength effect of the aqueous phase shows that the extraction of the metal increases with decreasing concentration of sulphate. At initially of about 10^?4?M with three different sulphate concentrations 0.033, 0.16 and 0.33?M in the aqueous phase, Zn(II) and Cd(II) are extracted as the complexes Zn(PMBP)₂ and Cd(PMBP)₂. Sulphate complexes of Zn(II) and Cd(II) are formed in the aqueous phase. The metal–sulphate interaction has been made in evidence by using the Debye–Huckel extended limiting law of ionic activity coefficient.     

Investigation of the use of diphenyl-2-pyridylmethane in benzene as an extractant for palladium from aqueous thiocyanate-nitrate solutions

The extraction of palladium/II/ with diphenyl-2-pyridylmethane /DPPM/ in benzene has been investigated from thiocyanate-nitrate media and optimized. Thiosulphate ions showed strong interference and reduced the extraction below 1%. Separation factors determined for most of the elements were better than 10³. This extraction method affords palladium preconcentration and its separation from Sc/III/, Co/II/, Cu/II/, Zn/II/, Se/IV/, Sr/II/, Ru/III/, Cd/II/, Cs/I/ and Eu/III/. Few possible applications of such separations have been cited.     

Extraction of molybdenum(V) as its ferron complex with trioctylamine in chloroform from a sulphuric acid medium

A simple, rapid, and highly selective method for the separation of molybdenum from a large number of elements of analytical importance has been developed. The method is based on the extraction of a Mo(V)-ferron (7-iodo-8-hydroxyquinoline-5-sulphonic acid) complex into trioctylamine-chloroform in a sulphuric acid medium using ascorbic acid as a reductant. Many elements such as Re(VII), W(VI), U(VI), Th(IV), Cr(III), Cr(VI), V(V), Ce(IV), Ru(III), Co(II), Ni(II), Mn(II), Fe(II), Fe(III), Cd(II), Mg(II), Cu(II), Al(III), Zn(II), Pb(II), Ag(I), and As(V) are not extracted under the conditions proposed and, thus, molybdenum can be easily separated without any interference. Sulphate, chloride, nitrate, phosphate, and oxalate anions have no effect on the extraction of molybdenum. However, zirconium and palladium interfere seriously. The ratio of Mo: ferron: TOA in the extracted species is found to be 1: 1: 3 using Job’s method of continuous variations. This value has been further confirmed by the mole-ratio method. The text was submitted by the authors in English.     

Inorganic polarography in organic solvents-I Some metal-pyridine-thiocyanate complexes in toluene

Results are reported for the direct application of polarography to the examination of organic phases following solvent extraction. Experimental factors such as suitable solvents, supporting electrolytes and electrode parameters have been studied and the method is tested for the extraction of the Cd, Co(II), Cu(II), Fe(II), Mn(II), Ni and Zn pyridine/thiocyanate complexes into toluene. The results show that the sensitivity is increased by the concentrating effect of the extraction system and better selectivity is achieved without searching for a suitable supporting electrolyte.