摘要:

The various methods for separation of carrier free radionuclides of second transition series elements from the bulk target matrix has been discussed in brief.

ISSN:0736-6299    

DOI:10.1080/07360299908934597

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

2,6-Di(5-alkyl-1,2,4-triazol-3-yl)-pyridine and 2,6-di(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine type compounds extract Am(III) 2-bromohexanoate and nitrate from acidic solutions (≤1 M HNO3) with an appreciable efficiency and selectivity, yielding Am(III)/Eu(III) separation factors of ≤150.

ISSN:0736-6299    

DOI:10.1080/07360299908934598

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

New aromatic dithiophosphinic acids (R2PSSH) with R = C6H5−, ClC6H4−, FC6H4−and CH3C6H4−were synthesized, characterized and tested as potential separating agents for trivalent actinides over lanthanides. The extraction of Am(III), Eu(III) and other lanthanides was carried out from nitric acid medium with mixtures of R2PSSHS and neutral organophosphorus compounds. There was no detectable extraction when R2PSSHS were used alone as extractants for either Am(III) or Eu(III) (DAM,EU.< 10−3) under the experimental conditions used in this study. High separation factors (DAM/DEU> 20) with DAM> 1 were achieved in the nitric acid range 0.1-1 mol/L by means of a synergistic mixture of bis(chloro-phenyl)dithiophosphinic acid + tributylphosphate (TBP), irioctylphosphine oxide (TOPO) or tributylphosphine oxide (TBPO). The high radiation resistance (up to 106Gy absorbed γ-doses) of the extractants was also demonstrated.

ISSN:0736-6299    

DOI:10.1080/07360299908934599

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Extraction of Pu(IV) and Pu(VI) from nitric acid media by the promising new extractant l-hydroxy-6-N-octylcarboxamide-2(1H)-pyridinone (octyl-1,2-HOPO) has been investigated. The effects of nitric acid, sodium, aluminum and iron(III) nitrates on extraction have been examined. Octyl-1,2-HOPO exhibits high specificity for Pu(IV) over a wide range of acidity and ionic strength. The affinity of octyl-1,2-HOPO for Pu(VI) is much less than for Pu(IV). However, the extraction of Pu(VI) is possible from acidic as well as from highly salted media. Two water soluble ligands, 1-hydroxyethane-1,1,-diphosphonic acid (HEDPA) and H(2,2)-1,2-HOPO, have been shown to be very effective for back extraction.

ISSN:0736-6299    

DOI:10.1080/07360299908934600

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Third phase formation in the extraction of Nd(III) by 0.2 M Octyl(Phenyl)-N,N-Diisobutyl Carbamoyl methyl phosphine oxide (OΦCMPO) in n-dodecane has been studied with tri-n-butyl phosphate (TBP) and tri-n-amyl phosphate (TAP) as modifiers to provide a comparison between these two modifier systems. The effect of concentration of TAP as modifier for the extraction of Nd(III) by 0.2 M OΦCMPO has been studied. The extraction of Nd(III) by TAP/n-dodecane in the absence of OΦCMPO has also been studied and the results are reported here.

ISSN:0736-6299    

DOI:10.1080/07360299908934601

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This report describes the second part of a theoretical approach aimed at establishing structure-activity relationships in a data base made of twenty-two monoamides (A) used as uranium (VI) nitrate extractants. It was found that predominant factors determining the extracting ability of a monoamide are of three kinds : i) electron density of the coordinating atoms or groups, which should be as high as possible ; ii) steric effects, which should be as low as possible ; and Hi) lipophilicity of the ligands, which should be above a minimum threshold value. In the first paper of this series[1], quantum chemistry calculations were reported to account for electronic properties of the ligands. This second paper reports molecular mechanics calculations made on UO2(NO3)2A2complexes in order to determine the influence of steric effects on the formation of these compounds. Calculations of monoamide lipophilicity using Rekker's method showed that all the molecules of the data base were lipophilic enough and, consequently, that this parameter was not significantly important for the extraction of uranyl nitrate by these monoamides. A quantitative relationship was established between the U(VI) distribution ratio and the two parameters, calculated by quantum chemistry and molecular mechanics methods.

ISSN:0736-6299    

DOI:10.1080/07360299908934602

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The aggregation of several metal complexes formed during solvent extraction with P,P'-di(2-ethylhexyl) methanediphosphonic acid, H2DEH[MDP], in deuterated toluene, has been investigated by small angle neutron scattering (SANS). The SANS results show that the Ca(II)-, Al(ni)-, La(III)- and Nd(III)-H2DEH[MDP] compounds exhibit little or no tendency to aggregate. Uranyl complexes of H2DEH[MDP] at high metal loading form small aggregates with an aggregation number of approximately 14. This behavior is in sharp contrast with the Th(IV)-H2DEH[MDP] system which forms large aggregates in the organic phase under high metal loading conditions. The aggregation behavior of the various metal-H2DEH[MDP] compounds is discussed in light of the information obtained from earlier solvent extraction, vapor pressure osmometry, and infrared spectroscopy studies.

ISSN:0736-6299    

DOI:10.1080/07360299908934603

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

N-dodecyl- and N,N-dihexylpyridinecarboxamides with amide group at 2, 3 or 4 position were synthesized. Model individual amides were used to recover copper(II) from chloride solutions at constant water activity and constant total concentration of dissolved species in aqueous solution. It was found, that pyridine-2-carboxamide forms with copper complexes (CuCl2)x(Ext)2. Remaining amides form with copper complexes CuCl2(Ext)2. Monoalkylamides are not suitable for extraction because they and their complexes are slightly soluble in the hydrocarbon diluents. N,N-dialkylpyridinecarboxamides and their copper complexes are sufficiently soluble in the hydrocarbon phase to carry out extraction. However, they are strong extractants and extract efficiently copper already from dilute chloride solutions ([Cl] = 0.1 M). They extract also significant amounts of copper from concentrated (3-4M) nitrate solutions.

ISSN:0736-6299    

DOI:10.1080/07360299908934604

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The extraction of Pt(IV) by Aliquat 336 (R3R'N+Cl−) in dodecane modified with 4% dodecanol from hydrochloric acid solutions has been investigated. The analysis of metal distribution data by numerical calculations suggested the formation of the species (R3R'N+)2PtCl62−in the organic phase with formation constant log β=5.26±0.02. The results obtained on Pt(IV) distribution have been implemented in a solid supported liquid membrane system, being NaClO4solutions the most effective to strip the metal from the organic solution. Influence of membrane composition and metal concentration on platinum transport have also been studied.

ISSN:0736-6299    

DOI:10.1080/07360299908934605

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Distribution of molybdenum (VI) between aqueous sulfuric acid solution and an organic solution containing Primene JMT has been studied.

ISSN:0736-6299    

DOI:10.1080/07360299908934606

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor