摘要:

AbstractThe extraction by TBP of nitrato complexes of metals occurs mainly by the formation of nonconducting complexes in which the oxygen of the PO group is covalently bound to the metal, e.g., P==0→M. In other TBP complexes, this O atom is bonded to hydrogen, e.g., to a hydrogen atom of water, of an undissociated acid, or of the hydronium ion.Three features in the extraction of metal nitrates at trace concentration from nitric acid concentrations>7Mwhich await interpretation are the second increase in the distribution coefficient,DM; the decrease in the magnitude of this second increase as the fraction of inert diluent increases; and the change in the temperature coefficient ofDMfrom negative to positive. Extraction (i) by bonding of the phosphoryl oxygen to an aquo group (of the aquonitrato metal complex), or (ii) by nitrato acids, do not explain these features.Measurements of the conductivity and viscosity of 100% TBP-HNO3-H2O phases are consistent with the existence of three steps as the ratio HNO3/TBP increases. In the first step, ions, postulated as (TBP·H2O·H)3O+and (TBP·H)2(H2O·H)O+, are formed. In the second step, the molar conductivity decreases as the predominant species becomes TBP·HNO3. In the third step the molar conductivity and the water content increase by the formation of ions such as (TBP·H)(H2O·H)(HNO3·H)O+, in which a nitric acid molecule is bonded to the hydronium ion: the second increase inDMfor certain metals is explained by there being similar bonding, through the oxygen of a nitrato group of the metal complex, in place of the HNO3in this complex ion when HNO3/TBP is>1. The positive temperature coefficient shown by this form of extraction of metal nitrates is also shown in this region by the extraction of nitric acid, the conductivity, and the water content.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26554

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractThe neutral organophosphorus derivatives: phosphines, phosphine oxides, phosphinates, phosphonates, and phosphates are briefly reviewed. All form metal complexes and all except perhaps the first have been studied in some detail in connection with solvent extraction.The physical and chemical properties of these compounds are considered as is the mechanism of extraction for acids and metal salts. Most extractions are straightforward consisting of hydrogen bonding for acids and solvation for neutral salts. The strength of these complexes can often be correlated with infrared or nuclear magnetic resonance (NMR) shifts.Metals display a wide range of extractibility depending on the reagent (solvent and diluent), the aqueous anion, the water activity, and the acidity. Selective extraction is often found for nitrate, per chlorate, perhaloacetate, and some chelating acid salts.Because of the relative simplicity of the solvation complexes and the variability in the solvent strength of the different phosphorus esters, several attempts at thermodynamic studies of the extraction process have been made. Rigorous treatment of most systems will be seen to be difficult and the results have only been moderately satisfactory. Some recent work is discussed.For large scale uranium-plutonium processing, tributyl phosphate is firmly entrenched. Several alternatives have been considered including both alkyl and phenyl phosphonates. For small-scale applications and for analytical separations the more expensive phosphinates and phosphine oxides may be useful.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26555

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractThe solvent-extraction properties of the sulfur analogs, both neutral and acid, of those organophosphorus compounds that have been used so extensively in solvent extraction have been investigated. These sulfur analogs have one or more oxygen atoms replaced by sulfur atoms. The neutral esters, trialkyl phosphorothioates, selectively extract Ag+and Hg+2from a nitric acid medium. In general, the acid esters, dialkyl phosphorothioic and -dithioic acids, extract from mineral acid solutions those metal ions that form insoluble sulfides. Dialkyl phosphorothioic acids appear to be more selective extractants than are the corresponding dithioic acids. The effects of various organic solvents, of concentration of mineral acid, and of concentration of dialkyl phosphorothioic and -dithioic acids were studied. The relative order of extraction and the limits of extraction were determined. The nature of the zinc di-n-butyl phosphorothioate and -dithioate complexes as they exist in the aqueous and organic phases were investigated.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26556

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractThis paper is concerned with solvent extraction studies that are used to study complex formation in the aqueous solution as well as in the organic solvent. In this hquid distribution method low metal concentrations can be used and the concentrations can generally be determined radiometrically. With proper choice of conditions, polynuclear reactions (e.g., formation of polynuclear hydroxo complexes) can be avoided, radioelements can be investigated, and the amount of complexing agent bound by the central ion can be neglected. Equilibria that have been investigated include the following types: (1) complexing in the aqueous phase with inorganic (e.g., OH−, Cl−,) and organic ligands (e.g., CH3COO−,), where the solvent extraction system is used to measure the concentration of the free metal ion; (2) complexing in both phases with extracting agents (e.g., acetylacetone, oxine); (3) residual coordination in neutral metal chelates or salts (e.g., UO2(NO3)2, UO2(TTA)2, UO2(R2PO4)2); (4) extraction of mixed chelate complexes.Mention is also made of systems that are not categorized by the above types.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26557

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE63-A26558

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE63-A26559

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE63-A26560

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE63-A26562

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE63-A26563

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE63-A26564

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor