摘要:

A series of hydrophobic tri- to hexa-dentate sulfur containing macrocyclic ligands incorporating aromatic and heteroaromatic subunits have been studied with respect to their extraction properties toward Ag(I), Hg(II), Au(III), and Pd(II) in aqueous//organic systems. The stoichiometry of extracted species and their extraction constants have been determined. The different ligands are compared with structure related open-chain compounds. The influence of substitution, solvent, and anion on the extraction equilibrium is also discussed providing a basis for future design of selective extractants and for die development of improved separation methods. The extractability of the various metal ions strongly depends on the nature and the number of donor atoms of the corresponding ligands and on the properties of the metal ion itself. In some cases, simple open-chain ligands show extraction properties comparable to the present macrocycles. A trithia crown with incorporated benzo subunit highly prefers Ag(I) to Hg(II). Furthermore a distinct selectivity for Au(ni) and Hg(II) over Pd(II) with pyridine substituted macrocycles was found.

ISSN:0736-6299    

DOI:10.1080/07366299408918220

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The extraction of Rh(III) from chloride solutions with 2 different 7-substituted 8-hydroxyquinoline (R-HQ) reagents was studied. Rh(III) was found to be extracted, to a limited degree, via an ion-pair involving the anionic hexachloro species of Rh(III), RhCl63−, and the protonated extractant. Through computer simulation of the extraction equilibria for one extractant, TN 1911, an extraction constant of log Kex= 5.8 was determined. The effect of age, contact time, [HCI], [CI−], [H+], and [SO42] on the extraction of Rh(III) with R-HQ reagents is reported.

ISSN:0736-6299    

DOI:10.1080/07366299408918221

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Studies of the extraction equilibria of platinum by chloroform solutions of 7-substituted-8-hydroxyquinoline derivatives from aqueous chloride media demonstrated that Pt(IV) is extracted as the ion-pair PtCl62−(H2Q+)2. The extraction equilibrium constants, log Kex, were determined to be log kex=3.48 and 3.62 for TN 1911 (an unsaturated and sterically-hindered derivative) and TN 2336 (a saturated and sterically-free derivative) respectively. It was found that PtCl62−(H2Q+)2exhibits an absorption band at 254.0 nm in chloroform solution. It was shown that platinum extraction is influenced by both the extractant concentration and reagent structure. The individual roles of platinum, proton and chloride ion concentration were quantified. It was found that platinum extraction is exothermic since metal extraction decreases with temperature and an enthalpy change of-39.8 kJ/mole was determined. The influence of pH on Pt(IV) stripping is also discussed. Finally, the respective extraction and stripping isotherms were established.

ISSN:0736-6299    

DOI:10.1080/07366299408918222

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Solvent extraction of palladiura(0) with bis(2,4,4,-trimethylpentyl) dithiophosphinic acid (CYANEX 301) and bis(2,4,4,-trimethylpentyl) monothiophosphinic acid (CYANEX 302) in n-heptane diluent was carried out. Measurement of palladium-loading capacity and stripping of palladium extracted by these extractants was also investigated.

ISSN:0736-6299    

DOI:10.1080/07366299408918223

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Model individual N-alkyl-3-pyridinecarboxamidee and N,N-di-alkyl-3-pyridinecarboxamides were synthesized and used for copper(II) extraction from chloride solutions. The stoichiometry of its reaction with copper(II) in chloride media was determined. N-alkyl-3-pyridinecarboxamides are stronger extractanta than N,N-dialkyl-3-pyridinecarboxamides but N-alkyl-3-pyridinecarboxamides and their complexes are slightly dissolved in the hydrocarbon diluents.

ISSN:0736-6299    

DOI:10.1080/07366299408918224

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Effects of α-acyloin oximes of various hydrophobicity upon copper(II) extraction rates with 2-hydroxy-5-alkylbenzophenone oximes was studied. Extraction rate depends mainly upon the hydrophobicity of 2-hydroxy-5-alkylbenzophenone oxime and sharply decreases when its hydrophobicity rises. The effect of a-acyloln oximes is small and more pronounced for more and less hydrophobic 2-hydroxy-5-alkylbenzophenone oximes and a-acyloin oximes, respectively, rising with the decrease of the aqueous phase acidity.

ISSN:0736-6299    

DOI:10.1080/07366299408918225

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The extraction of Mo(VI) from its aqueous solutions into chloroform, in the presence of 3-hydroxy-2-naphthoic acid (HNA) and n-butyltriphenylphosphonium bromide (LBr), was investigated using 99-Mo tracer, and the composition of extracted species was studied. The yellow extracts from diluted sulfuric acid solutions (0.5 mol dm−3H2SO4to pH 5) contained ion-associates of phosphonium cations (L+) with oligonuclear anionic complexes of Mo(VI) and HNA. Whereas the mean nuclearity of the extracted species was increasing slightly from 2.6 to 3.0 with pH increasing from 1.2 to 4.1, the content of HNA in the species increased simultaneously more than three times. The highest values of molybdenum distribution ratio were found at pH 3.0-3.2, where as much as 95% of the total amount of molybdenum was extracted at c(HNA) = 14.6 mmol dm−3, c(HNA)/c(Mo) = 147, in the form of the species with a mean composition expressed by a ratio L+: Mo: HNA = 3.1:2.7:1.4. A comparison with previously studied ion-pair extraction of Mo(VI), in the presence of 2,3-dihydroxynaphthalene as a chelating reagent, is given.

ISSN:0736-6299    

DOI:10.1080/07366299408918226

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Extraction of tri—, tetra— and hexavalent metal ions by N,N—N',N';— octabutylimidodiphosphotetramide has been investigated. Imidodiphosphoryl extractants show promise for treatment of nuclear waste but the optimum extractant structure must still be determined. Extraction of rare earths was investigated using two—phase potentiometric titrations as the more conventional slope analysis techniques could not be applied. The data thus obtained were analysed by the ESTA library of programs which was designed for modelling solution equilibria in aqueous phases. Results obtained showed that ESTA may be used for modelling two—phase systems providing corrections are made. Models were obtained for the extraction of Nd(III), Eu(III), Y(III) and Yb(III). Extraction equilibrium constants could be calculated as well as distribution ratios showing that imidodiphosphoryl extractants are promising as rare earth extractants. Extraction mechanisms were complicated with a number of species being formed proving that traditional slope analysis techniques for mechanistic determination would not have been successful here.

ISSN:0736-6299    

DOI:10.1080/07366299408918227

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The extraction equilibrium data of sulphuric acid and scandium(III) with bis(2,4,4-trimethylpenty)phosphinic acid (H[BTMPP]) from sulphuric acid solutions have been obtained. There are two extraction mechanisms of scandium(III) with H[BTMFP] at different ranges of aqueous acidity. The extraction of Sc(III) proceeds according to a cation exchange reaction at lower aqueous acidity and to a solvating reaction at higher acidity. The practicability of separating Sc(III) from Th(IV),Fe(III) and Lu(II) by controlling the aqueous acidity was discussed. The effect of temperature on extraction of Sc(III) was observed and thermodynamic, functions were caculated. IR and NMR spectra were made for organic extracts. The extraction characteristics of H[BTMPP] and di(2-ethylbexyl)phosphinic acid (H[DEHP]) were contrasted to obtain more information about extraction with H[BTMPP].

ISSN:0736-6299    

DOI:10.1080/07366299408918228

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The synergistic solvent extraction of trivalent lanthanides such as La, Eu and Lu and a trivalent actinide, Am, has been studied with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5 (HPMBP) and bis(2-ethylhexyl) sulphoxide (B2EHSO) or octyl(phenyl)-N,N-di isobutylcarbamoylmethylphosphine oxide (CMPO) in xylene. The extraction data have been analysed by both graphical and theoretical methods by taking into account aqueous phase speciation and all plausible complexes extracted into the organic phase. With HPMBP alone all the trivalent metal ions form M(PMBP)3.HPMBP type self adducts. With B2EHSO as a neutral donor, the synergistic adduct species are M(PMBP)3.B2EHSO and M(PMBP)3.2 B2EHSO (where M = La, Eu, Lu and Am), whereas with CMPO as a neutral donor the only complex extracted into the organic phase is M(PMBP)3.CMPO. The synergistic extraction constants of the above species which were deduced by non-linear regression analysis are found to increase monotonically with decreasing ionic radii of these metal ions.

ISSN:0736-6299    

DOI:10.1080/07366299408918229

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor