摘要:

Isotope effects for zinc upon complex formation with dicyclohexano-18-crown-6 were investigated. The single stage separation factor for unit mass difference (α = 1.013) was great compared with that of calcium isotopes. One of the isotopes,67Zn, showed a larger isotope effect than the other isotopes of even mass number.

ISSN:0736-6299    

DOI:10.1080/07366299308918161

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A molecular modelling method is used as an aid to predict and to account for the results of solvent extraction of dianions by an ion-exchange extractants such as diphosphonium compounds (polymethylenebis(trioctylphosphonium)s abbreviated as CnBP2+). The extraction ability of CnBP2+extractants was surprisingly dependent on the dianionic species and on the length of bridging methylene chain connecting the two phosphonium cationic centers which offers an effective molecular recognition field. The dianions studied are phthalate, isophthalate, terephthalate, dibenzoyltartrate and zinc oxalate complex. All of them have their negative charges carried by oxygen atoms. The extracted species considered for a dianion A2−are 1:1 and 2:2 ion-pair species such as (CnBP2+, A2−), (2 CnBP2+, 2 A2−rpar; with n = 2, 4, 6, 8, 10, 12. These ion-pair species are modelled and minimized. The total energy values obtained are processed to calculate the association energies of ion-pair species which allow comparison of 1:1 and 2:2 ion-pair species with the assumption that the ion-pair species with the smallest value of association energy should correspond to the most stable extracted species. It results that for phthalate isomers 1:1 association is the most favourable for n = 2, 4 and principally 2:2 association for n≥6. Graphical relationships have been obtained between total and association energies of modelled ion-pair species and experimental extraction percentages of extractable species taken from the literature. The association energy values of ion -pair species with phthalate isomers are compared with those of ion-pair species with dibenzoyltartrate and zinc oxalate complex previously studied.

ISSN:0736-6299    

DOI:10.1080/07366299308918162

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Increasing the steric hindrance of the substituents on the amidic nitrogen of the carbamoylmethylphosphine oxide class of extractants leads to a significant decrease in the tendency of these compounds to form a third phase during the extraction of nitric acid. An increase in steric hindrance leads to a reduction in the accessibility of the nitrogen and in the dipole-dipole and dipole-induced-dipole attractions between extractant molecules, thereby reducing the tendency to form a third phase. A corresponding increase in the amount of uranium that could be extracted without third phase formation was not observed due to a reduction in the interaction of the extractant with the diluent because of coordination with the metal ion by both polar groups.

ISSN:0736-6299    

DOI:10.1080/07366299308918163

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Five 4-acyl-3-phenyl-5-isoxazolones (AcyPI or HL) including three new compounds, 4-(4-toluoyl)-, 4-(4-fuluorobenzoyl)- and 4-(4-nitrobertzoyl(-3-phenyl-5-isoxazolones (TPI, FBPI and NBPI, respectively), were synthesized. The extraction of aluminium(III), gallium(IH) and indium (III) into benzene with the synthesized AcyPI has been investigated. The acid dissociation constants, Ka, and the partition coefficients, Kν, of AcyPI and the extraction constants, Kax, of their metal complexes were determined. The introduction of an electron-withdrawing fluoro or nitro group to the 4-position of the benzene ring in the acyl moiety of AcyPI was very effective for increasing the Kν. value of AcyPI, but scarcely affects the Kν value. The extracted species were ML3in all the extraction systems, where M denotes the metal ion.

ISSN:0736-6299    

DOI:10.1080/07366299308918164

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The extraction equilibria of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (commercial name, PC-88A, henceforth abbreviated as HR) dissolved in n-heptane were measured at 303 K. It was found that rare earth metals are extracted with the dimer of the extractant, (HR)2, as follows.

ISSN:0736-6299    

DOI:10.1080/07366299308918165

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

3-Pentanone (DEK.) is used in this work for the purification of wet process phosphoric acid (WPA) by extraction. The study of impurities (Fe, Al, Mg, SO4=and F¯) distribution between the conjugated phases generated shows that DFY. is very similar to isoamyl alcohol (iA) regarding its purification behavior. A review of the purification capability of all the solvents studied before is also presented. We have found a relation between the total impurities extracted and the amount of water plus phosphoric acid present in the organic phase. This relation would allow to predict the purification behavior of any solvent just from the data for the pure components.

ISSN:0736-6299    

DOI:10.1080/07366299308918166

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Solubility and liquid-liquid phase equilibrium data have been determined for the Water-Phosphoric Acid-3-Pentanone ternary system at 25 °C. Tie lines have been obtained and the plait point composition calculated. The phosphoric acid extraction capability of 3-Pentanone has been compared to that of other solvents previously studied. A systematic approach to the effects of chain length, functional group, branching and cyclation on the extraction power of the different solvents reported in the literature shows that the compatibility between solvent and phosphoric acid is higher for alcohols followed by ketones, esters and ethers. Branching and cyclation lead to a higher solubility of the acid into the organic phase, while an increase in the chain length results in a wider heterogeneous zone (i.e. in a decreasing solubility).

ISSN:0736-6299    

DOI:10.1080/07366299308918167

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A kinetic model for the interfacial reaction of copper extraction with Individual 1-(2'-hydroxy-5'-nonylphenyl)-1-ethanone (E)-oxime and 1-(2'-hydroxy-5'-methylphenyl)-1-decanone (E)-oxime having the same hydrophobicity was used to interpret the effect of hydroxyoxime partition and interfacial activity upon the rate of copper extraction from acidic sulfate solutions. Due to similar hydrophobicity of studied extractants the proposed model, which is very sensitive to the errors of the partition coefficient determination, cannot support any version of extraction mechanism.

ISSN:0736-6299    

DOI:10.1080/07366299308918168

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The kinetics of liquid membrane extraction of organic solutes (phenol, pyridine,m-toluidine, phenylalanine) from aqueous solution is studied. The experiments were carried out in a Lewis-type cell and in a liquid membrane device with flowing aqueous films and a circulating organic membrane liquid. From the results it can be concluded that when the goal is to obtain a more concentrated stripping solution, higher flow rates of the feed should be used; when a more complete recovery or separation of different organic solutes is aimed at, lower flow rates should be used.

ISSN:0736-6299    

DOI:10.1080/07366299308918169

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Partition coefficients of some cations between cation exchange membrane and solution were measured. The reciprocals of the partition coefficients were plotted against the corresponding: dimensionless concentrations of ions in solution. The relations obtained experimentally for monovalent-monovalent and monovalent-bivalent ions systems were in agreement with the respective theoretical equations. For the monovalent-monovalent exchange the relation was linear. While in the monovalent-bivalent case it was non linear. We proposed an empirically obtained linear relation for the monovalent-bivalent system. Therefore, the dependence of the reciprocal of partition coefficients on the dimensionless concentration of solution can be represented by a linear relation for both systems.

ISSN:0736-6299    

DOI:10.1080/07366299308918170

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor