SOLVENT EXTRACTION EQUILIBRIA OF TRIS(BENZOYL- TRIFLUOROACETONATO)COMPLEX OF COBALT(II) AND NICKEL(II) AS ION-PAIRS WITH TETRABUTYLAMMONIUM

Abstract

Solvent extraction of cobalt(Il) and nickel(II) in aqueous 1 mol dm^?3 NaCl solutions with benzoyltrifluoro-acetone(Hbfa) in carbon tetrachloride has been measured in the absence and presence of tetrabutylammonium(tba⁺). In the absence of tba⁺, M(bfa)₂ species is extracted and the extraction of cobalt(II) is better in the higher Hbfa concentration range but in the presence, M(bfa)₃ ^?tba⁺ type ion-pair is extracted and the extraction of nickel-(II) is always better. This is explained in terms that although the bis-nickel(II) complex is more stable, it is much more strongly hydrated than the bis-cobalt(II) complex and consequently its extraction is hindered but in the tris-complexes such a large difference of the hydration may not occur and the more stable nickel(II) complex is extracted better.     

SOLVENT EXTRACTION OF COPPER(II), NICKEL(II), AND COBALT(II) FROM SODIUM CHLORIDE SOLUTIONS BY OCTANAL OXIME

The extraction of divalent copper, nickel, and cobalt from sodium chloride solutions with octanal oxime (OCOX) was found to proceed by the following reaction:

The association of octanal oxime in toluene was taken into account in the modelling of the extraction reaction, and the formation constants for dimers and trimers were calculated using vapour-pressure osmometry. Stability constants for the formation of aqueous copper-chloro species were also calculated.     

Solvent-Extraction Behavior of Cobalt(II), Nickel(II), Copper(II), and Palladium(II) with Tri-n-butylphosphate

Abstract

A systematic study of the extraction behavior of cobalt(II), nickel(II), copper(II), and palladium(II) with TBP from thiocyanate system in various ranges of acid concentrations has been performed. The thiocyanate medium leads to enhanced extractions in all these cases compared to those in the previously used chloride medium. For palladium, the chloride and nitrate systems have been critically examined. Sixty-two per cent extraction occurs from 4 M hydrochloric acid using 100% TBP in a single run and the extraction becomes quantitative (>99%) after four successive equilibrations. A simpler method has been proposed for rapid extraction of palladium(II) as the thiocyanate complex. Quantitative extraction occurs in the presence of 1.2% thiocyanate solution from 0.5 to 2 M hydrochloric acid (initial) up to pH 8.0. The extractable species of cobalt(II), nickel(II), copper(II), and palladium(II) from thiocyanate medium are probably similar and of the type [M(CNS)₄]^2? [K·TBP·3H₂O]₂ ⁺ (buffer solution) and [M(CNS)₄]^2? [H·TBP·3H₂O]⁺ ₂ (acid solution). A simple extraction scheme has been worked out for the separation of palladium(II) from iron(III), cobalt(II), nickel, manganese(II), copper(II), and platinum.     

SOLVENT EXTRACTION OF COBALT AND NICKEL IN BIS (2,4,4-TRI-METHYLPENTYL) PHOSPHINIC ACID, “CYANEX -272”

ABSTRACT A study has been made of the extraction of cobalt and nickel from sulfate solutions into bis(2,4,4 tri-methylpentyl) Phosphinic acid - “Cyanex 272”, diluent Esso solvent DX 3641, for both high and low metal loading in the organic phase. In dilute solution, 0.01 M, extraction constants and enthalpies were determined for both metals. The extraction of cobalt was always favored over that of nickel, increasing with increase in temperature. No structure change with temperature was found for the cobalt-Cyanex complex. Phase modifiers were found to effect the selectivity of “Cyanex 272” for cobalt.

At high metal loading, equilibrium curves for cobalt were fitted using semi-empirical curve fitting, while for nickel a straight line variation was observed. Organic phase polymerization was observed for both metals the degree of aggregation increasing with increase in loading. A step change increase in the viscosity of the organic phase was observed at high cobalt loading. Phase modifiers proved to be ineffective In reducing the increase in organic phase viscosity.     

Recovery and Separation of Lanthanum(III), Aluminum(III), Cobalt(II), and Nickel(II) from Misch Metal by Solvent Extraction Using Bis(2-ethylhexyl) phosphinic Acid

Abstract

This paper describes use of bis(2-ethylhexyl) phosphinic acid as a reagent for extraction and mutual separation of lanthanum(III), aluminum(II), cobalt(II), and nickel(II) in 1.0 mol/L sodium nitrate. The extraction and stripping behavior of the four metal ions has been investigated using the extractant in Solvesso #150 as a diluent. The mutual separation and recovery of the metal ions from their mixtures has been tested by multistage extraction with a conventional separator funnel. A set of separation schemes has also been proposed for a continuous countercurrent multistage extraction which is comprised of ten extraction stages, four scrubbing stages, and seven stripping stages. Lanthanum(III) and aluminum(III) are coextracted but separated by selective stripping into different concentrations of hydrochloric acid. Cobalt(II) can be extracted with the nickel(II)-preloaded extractant solution, whereas nickel(II) remains in the aqueous phase. The successful separation of these metal ions from a misch metal-simulated sample is presented.     

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.     

SOLVENT EXTRACTION OF SILVER(I) AND MERCURY(lI) BY O,O-DI-n-BUTYL PHENYLAMINO-PHENYLMETHANETHIO PHOSPHONATE FROM CHLORIDE SOLUTIONS

The extraction of Ag(I)and Hg(II) from chloride solutions of constant ionic strength (lM) by O,O-di-n-butyl a -phenylamino--phenylmethanethiophosphonate dissolved in trichloromethane has been studied. The extraction dependences of metals on the ligand, hydrogen and chloride ions concentrations have been analysed to determine the stoichiometry of the extracted complexes and their equilibrium constants.

Evidence was found for the formation of the complexes     

Selective transport of cobalt (II) from ammoniacal solutions containing cobalt (II) and nickel (II) by emulsion liquid membranes using 8-hydroxyquinoline

The selective transport of cobalt (II) from ammoniacal solutions containing nickel (II) and cobalt (II) by emulsion liquid membranes (ELMs) using 8-hydroxyquinoline (8-HQ) as extractant has been presented. Membrane solution consists of a diluent (kerosene), a surfactant (ECA 4360J), and an extractant (8-HQ). Very dilute sulphuric solution buffered at pH 5.0 has been used as a stripping solution. The ammoniacal feed solution pH was adjusted to 9.0 with hydrochloric acid. The important variables governing the permeation of cobalt (II) have been studied. These variables are membrane composition, pH of the feed solution, cobalt (II) and nickel (II) concentrations of the feed solution, stirring speed, surfactant concentration, extractant concentration, complexing agent concentration and pH of the stripping solution, and phase ratio. After the optimum conditions had been determined, it was possible to selectively transport 95.0% of cobalt (II) from ammoniacal feed solution containing Co²⁺ and Ni²⁺ ions. The separation factors of cobalt (II) with respect to nickel (II), based on initial feed concentration, have experimentally found to be of as high as 31 for equimolar Co(II)–Ni(II) feed solution.     

Recycling of nickel–metal hydride batteries. II: Electrochemical deposition of cobalt and nickel

A combination of hydrometallurgical and electrochemical processes has been developed for the separation and recovery of nickel and cobalt from cylindrical nickel–metal hydride rechargeable batteries. Leaching tests revealed that a 4 mol dm^?3 hydrochloric acid solution at 95 °C was suitable to dissolve all metals from the battery after 3 h dissolution. The rare earths were separated from the leaching solution by solvent extraction with 25% bis(2‐ethylhexyl)phosphoric acid (D2EHPA) in kerosene. The nickel and cobalt present in the aqueous phase were subjected to electrowinning. Galvanostatic tests on simulated aqueous solutions investigated the effect of current density, pH, and temperature with regard to current efficiency and deposit composition and morphology. The results indicated that achieving an Ni? Co composition with desirable properties was possible by varying the applied current density. Preferential cobalt deposition was observed at low current densities. Galvanostatic tests using solutions obtained from treatment of batteries revealed that the aqueous chloride phase, obtained from the extraction, was suitable for recovery of nickel and cobalt through simultaneous electrodeposition. Scanning electron micrography and X‐ray diffraction analysis gave detailed information of the morphology and the crystallographic orientation of the obtained deposits. Copyright © 2004 Society of Chemical Industry     

SOLVENT EXTRACTION OF ZINC(II) BY ORGANOPHOSPHORUS ACIDS COMPOUNDS FROM PERCHLORATE SOLUTIONS.

ABSTRACT

The extraction of zinc from perchlorate solutions at 0.1 mol.dm^?3 of ionic strength by di(2-ethylhexyl)phosphoric acid (HDEHP), 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) and di(n-octyl)phosphinic acid (H[DOP]) dissolved in toluene has been studied at 25 ° C.

The distribution coefficient was determined as a function of pH and HA concentrations and the data were analyzed both graphically and numerically using the computer program LETAGROP-DISTR.

The results showed that the data can be explained assuming the formation of ZnA₂(HA)₂ and ZnA₂HA in organic phase for all the extractants used. A correlation between extracted species and concentration of the various extractants has been found.

The predominance of the different species into the organic phase has been correlated with the difference between their extraction constants.

The anion of the ionic medium is not extracted into the organic phase.     

SELECTIVE EXTRACTION OF PALLADIUM(II) FROM CHLORIDE SOLUTIONS WITH NONYLTHIOUREA DISSOLVED IN CHLOROFORM

ABSTRACT

The extraction of Palladium(II) [Pd(II)] from hydrochloric acid solutions with nonylthiourea (NTH) dissolved in chloroform at a constant ionic strength of 1.0?M has been studied. The extraction of Pd(II) has been investigated as a function of the concentration of the extractant, chloride ion, and proton concentrations as well as extraction temperature. The distribution data have been treated graphically and numerically. The analysis of the experimental data has shown that Pd(II) is extracted as PdCl₂·(NTH) and PdCl₂·(NTH)₂ species with the respective extraction constants of log?K ₁₁=5.0±0.1 and log?K ₁₂=9.1±0.1. The back-extraction of Pd(II) from the organic phase using different stripping reagents has been examined. The selectivity of NTH for Pd(II) against Pt(IV), Rh(III), Cu(II), Fe(III), and Zn(II) has also been investigated.     

Separation of cobalt and nickel from acidic sulfate solutions using mixtures of di(2‐ethylhexyl)phosphoric acid (DP‐8R) and hydroxyoxime (ACORGA M5640)

DP‐8R and ACORGA M5640 extractants diluted in Exxsol D100 were used to co‐extract cobalt and nickel from aqueous acidic sulfate media. The influences of equilibration time, temperature, equilibrium pH and reagent concentrations on the extraction of both metals have been studied. It was observed that both cobalt and nickel extraction are slightly sensitive to temperature but are pH dependent. Metal extraction equilibria are reached within about 5 min contact time. In addition, cobalt extraction depends on the extractant concentration in the organic phase. For a solution containing 0.5 g dm^?3 each of cobalt and nickel and an initial pH of 4.1, conditions were established for the co‐extraction of both metals and selective stripping (with H₂SO₄) of cobalt and nickel. Using the appropriate reagent concentrations the yield (extraction stage) for both metals exceeded 90%, and stripping of cobalt and nickel was almost quantitative. Copyright © 2004 Society of Chemical Industry     

Liquid–liquid extraction of Hg(II) from acidic chloride solutions using bis‐2‐ethylhexyl sulfoxide

The liquid–liquid extraction of Hg(II) from acidic chloride solutions has been studied using bis‐2‐ethylhexyl sulfoxide (B2EHSO) as an extractant. For comparison, extraction studies have also been carried out using di‐n‐octyl sulfoxide (DOSO) and diphenyl sulfoxide (DPhSO). The extraction data have been analysed by both graphical and theoretical methods taking into account aqueous phase speciation and all plausible complexes extracted into the organic phase. These results demonstrate that Hg(II) is extracted into xylene as HgCl₂.3R₂SO (where R₂SO represents the sulfoxide). The equilibrium constant of the extracted complex has been deduced by non‐linear regression analysis. The developed liquid–liquid extraction procedure has been applied for the recovery of mercury from the brine‐sludge of a Chlor‐Alkali plant. © 2001 Society of Chemical Industry     

EXTRACTION CHEMISTRY OF COBALT AND NICKEL BY DI(1-METHYLHEPTYL)PHOSPHINIC ACID

The fundamental characteristics and mechanism of extraction of cobalt (II) and nickel(II) by di-(1-methylheptyl) phosphinic acid (DMHPA) were studied. The extraction ability of cobalt(II), nickel (II) and various metals by DMHPA decreases in the order Fe(III) > Zn ? Pb(II) > Mn(II) > Cu(II) > Co(II) > Mg > Ca > Ni(II). The difference of the pH_½ values for nickel and cobalt reaches 2.06 pH units, which is apparently greater than those from extraction by di(2-ethylhexyl)phosphoric acid (DEHPA)and 2-ethyl-hexyl ester 2-ethylhexylphosphonic acid(DHEHPA).The slope analysis and IR spectroscopy reveal that the stoichiometrics of cobalt and nickel extracted species are Co(HA₂)₂ and Ni(HA₂)₂(H₂O)₂ respectively. As demonstrated by the study of the electronic spectroscopy the structure of the extracted complexes were shown as tetrahedral and octahedral configuration respectively. Furthermore, the coordination field parameters of the complexes were calculated.     

Effect of composition and ageing of chloride solutions on extraction of Rh(III) and Ru(III) with phosphonium ionic liquids Cyphos IL 101 and IL 104

ABSTRACT

Rhodium(III) and ruthenium(III) were extracted from chloride solutions with phosphonium ionic liquids trihexyl(tetradecyl)phosphonium chloride or trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate in toluene. Influence of HCl and NaCl presence in the feed and IL concentration in the organic phase were determined. Rh(III) transport appeared to be inefficient, while over 70% of Ru(III) was extracted from 3 M HCl. Ru(III) extraction was affected by the feed acidity and the type of extractant used. The spectra of the extracts indicated some changes in the structure of Rh(III) and Ru(III) complexes in the organic phase. Also, ageing of feed solutions on the extraction of Ru(III) and Rh(III) was studied.     

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.     

COBALT-NICKEL SEPARATION BY SOLVENT EXTRACTION WITH BIS(2,4,4 TRIMETHYLPENTYL)PHOSPHINIC ACID

Abstract

The use of an organophosphinic acid to separate cobalt from nickel by solvent extraction is described. Comparative data indicate that the phosphinic acid is superior to analagous phosphoric and phosphonic acids in terms of cobalt-nickel selectivity and the ability to reject calcium. Important reagent properties, such as low aqueous solubility and hydrolytic stability, are discussed. The results of continuous, counter-current, mini-plant tests demonstrate the recovery of high purity cobalt from concentrated nickel sulphate solutions.     

EXTRACTION OF NICKEL FROM AQUEOUS SULFATE SOLUTION INTO BIS(2,2,4-TRIMETHYLPENTYL)PHOSPHINIC ACID,CYANEX 272TM -EQUILIBRIUM AND KINETIC STUDIES

ABSTRACT

Equilibrium and kinetic studies have been carried out on the extraction of nickel from sulfate solutions using bis(2,2,4 trimethylpentyl) phosphinic acid HDTMPP, “Cyanex 272tm”- It was found that nickel extraction in HDTMPP was favored by the presence of sodium in the organic phase and that equilibrium nickel concentration could be written in terms of the pre-equilibrated extractant concentration

Kinetic studies were carried out using the rising drop method, reaction orders were determined with respect to the aqueous phase nickel concentration, Ni²⁺, the aqueous phase sodium concentration, Na ⁺ the pH, the organic phase dimer concentration ------ and the organic phase sodium salt concentration ---- In addition, it was found that the extraction kinetics could be explained in terms of an aqueous phase interfacial reaction accompanied by diffusion through the interface. Mass transfer coefficient values were determined indicating extraction rates for metal extraction into HDTMPP were the same order of magnitude as those found for HDEHP.     

DILUENT EFFECT ON THE EXTRACTION OF URANIUM(VI) FROM HYDROCHLORIC ACID SOLUTIONS BY TRIOCTYLMETHYLAMMONIUM CHLORIDE

ABSTRACT

The extraction of uranium(VI) from hydrochloric acid solutions by trioctylmethylammonium chloride (TOMAC) has been examined using various diluents such as benzene, chlorobenzene, o-dichlorobenzene, toluene, m-xylene, nitrobenzene, carbon tetrachloride, chloroform and 1,2-dichloroethane. It was found that by assuming a regular solution, the distribution coefficient and the enthalpy change associated with the metal extraction can be expressed in terms of the solubility parameter of TOMAC, diluent and the complex formed in the organic phase and their molar volumes. Additionally an empirical relation holds between distribution coefficient and the viscosity of diluent. Further results for the extraction of divalent manganese, cobalt, copper, zinc and cadmium from hydrochloric acid solutions by TOMAC are investigated in comparison with those of uranium(VI).     

COBALT–NICKEL SEPARATION: THE EXTRACTION OF COBALT(II) AND NICKEL(II) WITH BIS(2-ETHYLHEXYL) PHOSPHINIC ACID (PIA-8) IN TOLUENE

The extraction behaviour of cobalt(II) and nickel(II) from sulfate solutions with bis(2-ethylhexyl) phosphinic acid (PIA-8) in toluene has been studied. Quantitative extraction of Co(II) was observed at pH 5.0–5.9 while that of Ni(II) at pH 6.8–7.0 with 0.03 M PIA-8 in toluene. The difference in pH_0.5 for Co(II) and Ni(II) was 1.9. The stoichiometry of the extracted species were determined by slope analysis method. The extraction reaction proceeds by cation exchange mechanism and the extracted species were Co · R₂(HR)₂ and Ni · R₂ · 2(HR)₂. Temperature dependance of the extraction equilibrium constants were determined to estimate the apparent thermodynamic functions (ΔG, ΔS and ΔH). The method was used for separation of cobalt(II) and nickel(II). Cobalt(II) was separated from nickel even at 1:20 (Co:Ni) ratio. The separation of cobalt(II) from nickel(II) was favoured with the increase in temperature.