摘要:

A study of the extraction of copper salts from aqueous solutions into an equimolar solution of a long-chain amine and a long-chain carboxylic acid in toluene has shown that a cationic copper aggregate is formed in the organic phase. A mechanism of the extraction process and a model structure of the aggregate are proposed based on UV-visible, and NMR spectra, water solubilization, and computer-aided model design (CAMD).

ISSN:0736-6299    

DOI:10.1080/07366299108918079

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The solvent extraction of antimony (in), bismuth (111), lead (II) and tin (IV) from aqueous hydrochloric acid solutions by bis(2,4,4-trimethylpentyl) phosphinodithioic acid (Cyanex 301® denoted HL) in kerosene + 10 % v/v n-decanol was investigated. Lead (II), tin (IV), bismuth (III) and antimony (III) are efficiently extracted by Cyanex 301® up to about 5, 6, 9 and 11 mol.L1−HCl, respectively. The corresponding extracted species were identified as PbL2, SnCl2L2, BiL3and SMvj. However, it was observed that Sn (IV) can be moderately extracted from the aqueous phase by the mere mixture of kerosene and n-decanol above 9 mol.L1−HCl. In all cases, extraction equilibrium was reached within a few minutes. Finally, a thermodynamic modelling of the extraction system was developed in the particular case of lead (II).

ISSN:0736-6299    

DOI:10.1080/07366299108918080

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The alkalyne leaching of spent alumina-based catalysts from the petroleum industry, containing molybdenum and/or vanadium among other metals, yields a solution rich in Mo(VI), V(V) and Al(III). In order to recover the two heavy metals aluminum must be first quantitatively separated. Several routes were theoretically tested by computer simulation. Finally, the extraction of aluminum with oxine was chosen. A commercial reagent similar to oxime, LIX 26 (Henkel), was used. The extraction of the three metals with several organic phases containing LIX 26 /n-octanol /hexane was systematically studied.|The best separation conditions were found to be 7<pH<8, 0.3% LIX 26 and 10% n-octanol. A two step counter-current extraction with equal volumes of the two phases gives 99.6% extraction of Al(III) with less than 1 ppm of Mo(VI) and V(V). The organic phase can be regenerated by contacting with sulphuric acid, at pH<2, where aluminum is quantitatively stripped.

ISSN:0736-6299    

DOI:10.1080/07366299108918081

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The potential of the chelate extraction mode displayed by diamine extractants is illustrated by using two tertiary diamine extractants to extract palladium(II) and platinum(IV) from a base metal solution containing copper(II), nickel(IT), cobalml) and iron(III) in 1 mol/dm3lithium chloride. The extraction behaviour of the diamine extractants is compared with that of the commercially-available extractants Alamine 336 (a tertiary monoamine extractant) and Aliquat 336 (a quaternary monoammonium chloride salt). By exploiting the chelate extraction mode, specific to diamine extractants, separation of palladium(IT) from platinum(lv) can be achieved. The only base metal ion that is extracted is iron(III). Iron(III) can be stripped with 1 mol/dm3sulphuric acid or the extraction can be performed under mildly acidic conditions, e.g. pH 4.7. Under the latter conditions ironflll) precipitates quantitatively as a hydroxide complex and can be removed by filtration. The selective back-extraction of palladium(II) and platinum(lV) by thiourea in hydrochloric acid and sodium thiocyanate respectively is demonstrated.

ISSN:0736-6299    

DOI:10.1080/07366299108918082

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Solvent extraction of platinum(IV) and palladium(II) with tri-n-octylamine(TOA) in o-xylene from 4.0M (Na,H)(Cl, HSO4) has been investigated at 298K in order to compare with similar extraction by trioctylphosphine oxide(TOPO). The dependence of the distribution ratio of platinum(IV) and pal 1adium(II) on TOA, hydrogen ion and chloride ion concentrations suggests the dominant extracted species of these metals would be 2:1 for proto-nated amine : chlorocomplex anion and the extraction should be essentially anion exchange reaction. The extraction constants (Kex = D[H+(T0A)C1 ] 2[C1 ]2), were evaluated as 106-3and 105.8for platinum(IV) and pal ladium(II), respectively. The anion exchange with protonated TOPO salt represented by H(T0P0)2+C1 is less than that with protonated TOA salt by a factor of one order.

ISSN:0736-6299    

DOI:10.1080/07366299108918083

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The synergistic extraction of zinc and cadmium (M2*) from sulphate, nitrate and perchlorate media with mixtures of 1-phenyl-3-methyl-4-benzoylpyra2ol-5-ol (HL) and n-dodecylammoniura salts (DDAH*,X−) in toluene has been studied. In sulphate medium, the lipophilic ammonium pyrazololate (DDAK*L−) is the predominating ammonium species : the synergy observed can be considered as the addition of (DDAH*,L−) on HL2perchlorate and nitrate media, the amphiphilic ammonium salts {DDAH*, CIO4−) and (DDAH+N03−) predominate, leading to the formation of an aqueous emulsion in equilibrium with a clear organic phase. Metal distribution curves show that the formation of the lipophilic synergistic species (DDAH+ML2−) results from a X−/ML3−exchange in the interfacial region between the aqueous and the organic phase. The addition of n-octanol or 4-nonylphenol in the organic phase turns the emulsion into a micro-emulsion whereas the substitution of toluene by chloroform largely decreases the emulsion stability.

ISSN:0736-6299    

DOI:10.1080/07366299108918084

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Possible reasons for significant enhancement of solvent extraction of some metals with dialkylphos-phoric acids in the presence of Zr(IV) and Hf(IV) are critically discussed, taking into consideration both the literature and the autors'data on the structure of acidic salts formed by these acids with Zr(IV) and Hf(IV). The chemistry of extraction of nitric acid, FeUII) and Eu ( I I I ) with Zr(IV) and Hf(IV) salts of di-2-ethy1hexy1 phosphoric acid (HX) has been studied using IR and31P NMR spectroscopy. Nitric acid is extracted by these salts due to interaction with their acceptor sites that results in the formation of a new polymeric extractant with bidentate anions of two types, (X-H-X)- and (X-H-N03)_. Protons of these groups can be exchanged with metal cations extracted, e.g., with Fe(III) or Eu(I 11 ), heteropolynuc1 ear complexes with non-equivalent (chelating and bridge) N03anions being formed during the extraction. The composition and structure of coordination polyhedrons formed around Zr(IV), Hf(IV), Fe(III) and Eu(III) have been determined. The reasons for a higher extraction ability of the salts studied for Fe(III) and Eu(III) versus D2EHPA itselfaredescribed.

ISSN:0736-6299    

DOI:10.1080/07366299108918085

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Slope analysis is critically examined as a stand-alone method for analyzing the representative extraction system uranyl nitrate, nitric acid, sodium nitrate, water, di-2-ethylhexylsulfoxide (DEHSO). n-dodecane at 25°C. The use of detailed computer calculations of free extractant concentrations and activity coefficients has permitted assessment of commonly employed assumptions of slope analysis in the data treatment. On the basis of slope analysis alone, the extraction of nitric acid in the absence of U(VI) can be partly described by the formation of the 1:1 adduct (DEHSO)(HNO3), but complications due to nonideality effects and the formation of at least two other species hinder further reliable analysis. Under the limiting conditions of low DEHSO molarity, low aqueous nitric acid molarity, and low U(VI) loading, a slope-analysis treatment of U(V1) extraction data shows unambiguously that the predominant extracted species of U(VI) is UO2(N03)2(DEHSO)2(H20)w(w not determined). However, it is difficult to treat graphically the complicated effects arising from multiple equilibria and changing activity coefficients that occur under any but the limiting conditions, and typical simplifying assumptions applied without appropriate corrections produce misleading results. In fact, a cancelling of effects obscures the true power dependence of the U(V1) distribution coefficientDuon DEHSO concentration at DEHSO concentrations greater than ca. 0.03 M. Thus, the advantage of simplicity in slope analysis is balanced by its limited applicability and reliability. However, with due care, slope methods of equilibrium analysis may furnish a valid, though limited, description of an extraction system, aiding further study by other techniques such as computer modeling.

ISSN:0736-6299    

DOI:10.1080/07366299108918086

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The sorption of cesium and strontium Ions from water solutions on natural zeolite follows the Freundlich-Langmuir Isotherm.The fractional consecutive batch adsorption can be optimized by a relative change of the sorbent:solutlon ratio (batch factor) for each of the radionuclides, using parameters of the isotherm and an empirical decontamination factor from an initial step.

ISSN:0736-6299    

DOI:10.1080/07366299108918087

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Advances in solvent extraction of metal ions with sulphonic acids is reviewed for the period 1973 to the present. Physical aspects of micelle formation and water uptake by the extractant are dealt with as well as applications to specific systems. The synergism of mixtures, notably those containing crown ethers, is reviewed.

ISSN:0736-6299    

DOI:10.1080/07366299108918088

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor