摘要:

The extraction behaviour of technetium, thorium, uranium, neptunium, plutonium, americium and curium in the Aliquat-336 (diluted with 1,3-diisopropyl benzene) - nitric acid system have been studied. Aliquat-336 (tricapryl-methyl ammonium nitrate) is a quaternary ammonium salt extracting different species with an anion exchange mechanism. Distribution data obtained are modeled by anion exchange (technetium) and ion-pair formation mechanisms (actinides) with the extraction of nitric acid included to account for the lowering of the free extractant concentration. Reasonably high distribution ratios were obtained for technetium and the tetravalent elements (Th, Np and Pu) and Aliquat-336 can therefore be useful for partitioning of these elements.

ISSN:0736-6299    

DOI:10.1080/07366299908934654

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The extraction of europium(III) nitrate from sodium nitrate with a series of tetrahexylmalonamides has been investigated. The tetrahexylmalonamides considered were N.N.N’N’-tetrahexylmalonamide (THMA), N,N,N’N’-tetra-hexyl-2-methylmalonamide (MeTHMA), and N,N,N’N’-tetrahexyl-2,2-dimethy-lmalonamide (DiMeTHMA). This series allowed for a systematic determination of the effects of alkyl substitution of the methylene carbon. Equilibrium modeling of the extraction data indicates that the malonamide/Eu ratio in the extracted complexes is 3 for all three malonamides investigated. This stoichiometry is different than that determined for isolated complexes. This can be rationalized by the formation of complexes with monodentate-bound diamide ligands in the extracts. The extraction constant for Eu decreases by seven-fold in going from THMA to MeTHMA, and a precipitous drop in the extraction constant occurs upon substitution of a second methyl group on the methylene carbon (i.e., for DiMeTHMA).

ISSN:0736-6299    

DOI:10.1080/07366299908934655

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO3solutions by phosphoryl-containing podands of various structures has been studied. It has been found that the maximum extraction of rare earth elements is exhibited by reagents containing one ether oxygen atom in the molecule, bound to diphenylphosphoryl or ditolylphosphoryl containing podands towards REE varies in a wide range, depending on the number of oxygen atoms in the polyether chain and the structure of the fragment connecting the ether oxygen atom with the terminal PO group. The podand structure which ensures a polydentate coordination of the reagent molecule to yield chelate complexes is favourable for REE extraction. The replacement of phenyl radicals in the podand VII molecule for butyl ones (compound IX) drastically reduces REE extraction. REE extraction by podands VII and VII increase from La to Lu with a decrease in the radii of extracted ions

ISSN:0736-6299    

DOI:10.1080/07366299908934656

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The extraction of cesium nitrate from a mixture of alkali metal nitrates by calix7lsqb;4]arene crown-6 ethers in 1,2-dichloroethane diluent has been surveyed at 25 °C. The results reveal that smaller substituents (but larger than C2,) at the phenolic positions of the calixarene opposite the crown ether increase both the extraction efficiency and the cesium selectivity. Benzo substituents on the crown ether tend to decrease extraction strength while increasing cesium-to-sodium selectivity. Conversely, a cyclohexano group on the crown ether has a negative impact on both extraction strength and selectivity.

ISSN:0736-6299    

DOI:10.1080/07366299908934657

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Dicyclohexano- 18-crown-6 (DC18C6), dissolved in chloroform, 1-octanol, toluene or cyclohexane, was irradiated by60Co γ-rays. Radiolytic destruction of DC18C6, measured by gas chromatography, decreased in the order: chloroform > cyclohexane > 1-octanol > toluene. Distribution coefficients in the solvent extraction of strontium from nitric acid solution were measured. These distribution coefficients were minimally affected by γ-irradiation in toluene solution, but decreased with the absorbed dose in chloroform solution. It was suggested that the distribution coefficient for the liquid-liquid extraction system was influenced by radiolytic products. The effect of radiolytic products on the distribution coefficients was evaluated by considering DC18C6 remaining in the organic phase after irradiation. The distribution coefficient measured for the organic phase with radiolytic products was larger than that without radiolytic products. The radiolytic products were thus shown to contribute to the increase in the distribution coefficient.

ISSN:0736-6299    

DOI:10.1080/07366299908934658

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The extraction of palladium (II) from chloride solutions (over a wide region of aqueous acidity) by di(2-ethylhexyl)dithiophosphates of tetraoctylammonium, tri-n-octylammonium and di-n-octylammonium in toluene at the constant chloride concentration has been studied. A synergistic effect was shown to be observed in these systems and it is explained by the formation of unusual complexes with mixed ligands. It has been established the palladium complexes, such as (R3NH)[PdCl2A], (R3NH)[PdCl2A] and (R2NH2)[PdCl2A], involving both alkylammonium cation and dialkyldithiophosphate anion are extracted under conditions of the loaded organic phase using distribution methods depending on a composition of aqueous and organic phase. At the excess of R3NHA or R2NH·HA, PdA2is extracted into the organic phase. Table 8 reports the results obtained and indicates the domains of existence of the various species of palladium (II) extracted into the organic phase in the binary ex-tractant systems in comparison with the initial systems

ISSN:0736-6299    

DOI:10.1080/07366299908934659

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Based on a variety of selected examples, we illustrate the power of molecular dynamics (MD) simulations to gain microscopic insights into systems involved in the liquid-liquid extraction of cations by macrocylic or acyclic ionophores such as calixarene derivatives, cryptands, podands. Explicit account of solvation in the source phase (water), in the receiving phase (chloroform) and at the liquid-liquid interface demonstrates the active role of solvent on the structural features of the extracted complexes and on the effect of counterions. Solvent also markedly contributes to the thermodynamics of cation complexation in homogeneous liquids and of transfer from one liquid phase to the other.

ISSN:0736-6299    

DOI:10.1080/07366299908934660

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The feasibility of using trialkylphosphine oxides to remove cadmium from mixed, acidic chloride-phosphate systems was investigated. Interpolations from extraction isotherms indicated that raffinates containing very low levels of cadmium (approximately 0.5 mg/L) could be produced readily. Stripping was accomplished with water. The co-extraction of acids was minimal.

ISSN:0736-6299    

DOI:10.1080/07366299908934661

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The composition of commercial reagent CYANEX®925 was investigated by GC and GC/MS. It was found that CYANEX®925 contains 5 isomers of trioctylphosphine oxide with branched and normal alkyl chains. The content of the active substance is estimated as equal to 98.5%.

ISSN:0736-6299    

DOI:10.1080/07366299908934662

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Cyanex 923 has been proposed as an extractant for the removal of sulphuric acid from copper tank house bleed streams. This process requires many stages and so is ideal for column operation. This paper presents a comparison between three types of column for this service. The new SMR packing marketed by Glitsch is the first packing developed specifically for liquid-liquid extraction service and is compared with a column packed with Raschig rings and a pulsed perforated plate column.

ISSN:0736-6299    

DOI:10.1080/07366299908934663

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor