Solvent extraction separation of In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/ with sulphoxides

Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated.     

Solvent extraction of Cobalt/II/ from thiocyanate solutions by sulphoxides

The extraction of cobalt/II/ from ammonium thiocyanate solutions by di-n-pentyl sulphoxide /DPSO/, di-n-octyl sulphoxide /DOSO/ and their mixtures in carbon tetrachloride has been studied. The species extracted were found to be Co/SCN/₂. 4S /where S=DOSO or DOSO/. Synergic effects have been observed which are ascribed to the formation of mixed ligand metal complexes. The influence of the metal concentration, temperature and the diluent on the extraction of cobalt/II/has been investigated.     

Solvent extraction of zinc/II/ with sulphoxides: Theoretical analysis of extraction behaviour

This paper describes a theoretical method for analyzing the behaviour of⁶⁵Zn during solvent extraction from ammonium thiocyanate solutions with dialkyl sulphoxides. The mechanism of extraction of Zn/II/ from thiocyanate medium by sulphoxides may be represented by the following general equation: $$xM_{aq}^{m + } + ySCN_{aq}^ - + zS_{org} \rightleftharpoons [M_x /SCN/_y ]^{mx - y} .zS_{org} $$ where M^m+ is the metal ion and S is the extractant. Expressions for the distribution coefficients were derived taking into account complexation of the metal in the aqueous phase by inorganic ligands and also the dissociation of the extracted ion-pairs in the organic phase. Using these expressions, the values of the extraction constants were determined by a least-squares fit with the experimental extraction data. From these extraction constants, the various species extracted into the organic phase were resolved. The influence of the metal concentration, temperature and the diluent on the extraction of Zn/II/ has been investigated.     

Solvent extraction of zirconium from hydrochloric acid solutions by sulphoxides and their mixtures

The solvent extraction of zirconium from HCl solutions by dipentyl sulphoxide (DPSO), dioctyl sulphoxide (DOSO), tributyl phosphate (TBP), and their mixtures in various solvents has been studied. At a given H⁺ strength, the extraction coefficient η of the metal increases with an increase in Cl⁻ activity whereas it is almost independent of H⁺ at constant Cl⁻. Under otherwise identical conditions, η increases with an increase in the extractant concentration but is virtually independent of the metal ion concentration over a wide range. The species extracted are ZrCl₄·DPSO, ZrCl₄·DOSO, and ZrCl₄·2TBP. In the case of mixtures, the slope of the log η−log M extractant plot for one component decreases with an increase in the concentration of the second component, the lines crossing at a common point. Extraction is favoured by solvents of low dielectric constant. It is possible to separate zirconium from thorium and uranium by solvent extraction with sulphoxides.     

Solvent extraction separation of iron(III) and aluminium(III) from other elements with Cyanex 302

A rapid method was developed for the solvent extraction separation of iron(III) and aluminium(III) from other elements with Cyanex 302 in chloroform as the diluent. Iron(III) was quantitatively extracted at pH 2.0-2.5 with 5 x 10(-3) M Cyanex 302 in chloroform whereas the extraction of aluminium(III) was quantitative in the pH range 3.0-4.0 with 10 x 10(-3) M Cyanex 302 in chloroform. Iron(III) was stripped from the organic phase with 1.0 M and aluminium(III) with 2.0 M hydrochloric acid. Both metals were separated from multicomponent mixtures. The method was applied to the separation of iron and aluminium from real samples.     

Solvent extraction separation of rhodium(III) with N-n-octylaniline as an extractant

Solvent extraction separation method for the determination of rhodium(III) has been described. Selective and quantitative extraction of rhodium(III) by N-n-octylaniline, a high molecular weight amine (HMWA) into xylene takes place from aqueous sodium malonate medium. The effect of concentration of malonate, N-n-octylaniline, role of various diluents, stripping agents and foreign ions on the extraction of rhodium(III) has been studied. The procedure offers distinct improvements in need of real sample analysis and environmental safety as the extraction procedure carried out in weak organic acid media.     

Solvent extraction of Co/III/ by benzoylacetone from acetate solutions

The extraction of Co/III/ by benzoylacetone solutions has been carried out from acetateacetic acid solutions. The effect of different parameters affecting the distribution coefficient of Co/III/ have been determined. Lg D for Co was found to be a third order dependent on extractant concentration and a negative first order with respect to [H⁺]. From the thermodynamic parameters and the data of distribution ratios, the extraction mechanism has been suggested. Addition of some electron donor compounds shows no possibility for the increase of coordination number.     

Solvent extraction of cerium/III/ with 1-/2-pyridylazo/-2-naphthol from perchloric acid media

A study on solvent extraction of cerium/III/ ion with 1-/2-pyridylazo/-2-naphthol /PAN or HL/ in chloroform from perchloric acid solution is described. The effect of equilibrium time, the pH of the aqueous phase and the concentration centration of extractant in organic phase on the extraction efficiency of cerium/III/ has been studied. The results show that the mechanism of extraction reaction is 3Ce _/aq/ ³⁺ + 3HL_/o/ CeL_3/o/ + 3H ₊ ^/aq/     

Solvent extraction of Co/III/ with 1, 2, 3-benzotriazole into n-butanol

A new and rapid method has been developed for the quantitative extraction of Co/III/ with 1, 2, 3-benzotriazole into n-butanol. The extraction coefficient value of Co/III/ between n-butanol and an aqueous 5% solution of 1, 2, 3-BT in 2M sodium acetate-acetic acid buffer showed a maximum value of E=280 at pH 8.5. The effect of various other parameters on the extraction coefficient of Co/III/ such as solvents, anions, cations etc. has also been studied. The stoichiometry of the metal: reagent determined by the method of substoichiometric extraction and slope-ratio method was found to be 12. The separation factors studied for most of the elements were found to be better than 10³.     

Solvent extraction of In/III/ with 1,2,3-bezotriazole into n-heptanol

Aqueous 1,2,3-benzotriazole has been used for the extraction of In/III/ in alkaline medium. The extraction of In/III/ was found to be better than 99% over the pH range 5.0–10.0 and an equilibration time of 2.0 min. The effect of anions and cations on the extraction coefficient has been studied. The stoichiometry of metal: reagent determined by the slope-ratio method was found to be 13. Separation factors for around 20 elements were better than 10³.     

Solvent extraction of Au/III/ with 1,2,3-benzotriazole into n-butanol

Aqueous 1,2,3-benzotriazole/1,2,3-BT/ has been used for the extraction of Au/III/ from acidic medium into n-butanol. The extraction of Au/III/ was found to be better than 98% over the pH range 2.0–7.0 and an equilibration time of 2.0 min. The effect of anions and cations on the extraction coefficient has been studied. The stoichiometry of metal: reagent determined by the slope ratio method was found to be 13. Separation factor for many elements in the extraction of Au/III/ has been evaluated.     

Solvent extraction of Fe/III/ with 1,2,3-benzotriazole into n-heptanol

A new and rapid method has been developed for the quantitative extraction of Fe/III/ with 1,2,3-benzotriazole /1,2,3-BT/ into n-heptanol. The extaction coefficient value of Fe/III/ between n-heptanol and an aqueous 1% solution of 1,2,3-BT was found to be better than 99% over the pH range of 7.3 to 8.0 for an equilibration time of 2.0 min. The effect of various other parameters on the extraction coefficient value of Fe/III/ such as solvents, anions and cations etc. has also been studied. The stoichiometry of the metal: reagent determined by the method of substoichiometric extraction and slope-ratio method was found to be 13. Separation factors for most of the elements studied were better than 10³.     

Mixed-ligand chelate extraction of neodymium(III) with thenoyltrifluoroacetone and various sulphoxides

Mixed-ligand chelate extraction of Nd(III) into benzene with mixtures of thenoyltrifluoroacetone (HTTA) and bis-2-ethylhexyl sulphoxide (B2EHSO) or di-n-octyl sulphoxide (DOSO) or diphenyl sulphoxide (DPhSO) or trioctylphosphine oxide (TOPO) from thiocyanate solutions has been studied. A very high synergistic enhancement of the order 10(3) has been observed in these systems. Thus this mixed-ligand chelate system may be useful in the extraction and separation of Nd(III) from other metal ions. The mechanism of extraction can be explained by a simple chemically based model presented in this paper.     

Solvent extraction of silver/I/ with 2,4-dihydroxy-acetophenone thiosemicarbazone

The solvent extraction of silver/I/ is carried out in acetic acid-sodium acetate buffer solution at pH 5.0 by 2,4-dihydroxyacetophenone thiosemicarbazone /DATS/. Ethyl acetate has been used as a solvent and is found that single extraction is sufficient to remove silver/I/ completely from the aqueous phase. Silver/I/ forms 11 complex /metalreagent/ with DATS. The effect of diverse ions on the extraction of silver/I/ has been investigated.     

Solvent extraction of silver/I/ from dilute cyanide solutions with 2,4-dihydroxyacetophenone thiosemicarbazone

The solvent extraction of silver/I/ has been carried out in 0.5M nitric acid in presence of cyanide by 2,4-dihydroxyacetophenone thiosemicarbazone /DATS/. Ethyl acetate has been used as a solvent and quantitative recovery is made possible with 12.5-fold excess of the reagent in a single extraction. In this medium silver/I/ forms a 22 complex /metal:ligand/ with DATS. The effect of diverse ions on the extraction of silver/I/ has been investigated.     

Solvent extraction and separation of gallium(III), indium(III), and thallium(III) with tributylphosphate

A systematic study has been made of the solvent extraction behaviour of milligram amounts of gallium(III), indium(III), and thallium(III) with TBP from hydrochloric acid, and of thallium(III) from nitric acid, sulphuric acid and buffer solutions of different pH. The effect of the metal ion concentration, acid concentration, reagent concentration, salting-out agent, and diverse ions have been critically examined. A scheme for separation of gallium(III), indium(III), and thallium(III) from each other and for their determination is proposed.     

Solvent extraction of neptunium(IV) from nitric acid solutions by sulphoxides and their mixtures

Studies have been performed on the liquid-liquid extraction of neptunium from nitric acid solutions by di-n-hexylsulphoxide (DHSO) di-no-octylsulphoxide (DOSO) and di-iso-amylsulphoxide (DISO) and their mixtures over a wide range of conditions. At a given strength of the extractant, extraction of Np(IV) increases initially rapidly with increase in the acid concentration; at high acidities, above 8M HNO₃, the extraction decreases. Under otherwise identical conditions, extraction increases with an increase in the extractant concentration. The species extracted would appear to be Np(NO₃)₄·2(R₂SO). A mixture of two extractants extracts more than the sum of the extractions due to the individual components at concentrations corresponding to those of the mixture. After loading the organic phase with uranium(VI), extractability of Np(IV) becomes considerably lower. The diminution in extraction with increase in temperature is small. A comparison of the extraction behaviour of Np(IV) with those of Pu(IV), U(VI) and some associated fission products has been made.     

Solvent extraction separation of gallium with 18crown6 from chloride media

Gallium was quantitatively extracted with 0.02M 18crown6 in methylene chloride from 6M hydrochloric acid, then stripped with 1M acetic acid and determined with 2-(pyridylazo)naphthol with measurement at 545 nm. Gallium was separated from indium, thallium, lead, aluminium and bismuth. The method was applied to determination of gallium in bauxite.     

Solvent extraction separation of zirconium from malonate solution with high molecular-weight amines

Zirconium is quantitatively extracted with 4% Amberlite LA-1 or LA-2 in xylene, from 0.01 M malonic acid medium at pH 3.0 and stripped from the organic phase with 2M hydrochloric acid, then determined spectrophotometrically at 665 nm as its complex with Arsenazo III. Zirconium is separated from various other elements by selective extraction and stripping. The method has been applied to the analysis of zircon.