摘要:

A variety of dibenzocrown ethers have been evaluated for the extraction of cesium from acidic nitrate media. Compounds incorporating a 21-crown-7 moiety are shown to exhibit greater cesium/sodium selectivity, superior functional stability, and better compatibility with PUREX-like diluents than dibenzocrown ethers with other ring sizes. The cesium distribution ratios obtained with these compounds, however, are generally not large enough to be of practical value. Higher Dcsvalues are achieved with several dibenzo-18-crown-6 derivatives. Of these, the best results are achieved with 4,4'(5')-di-[(l-hydroxy-2-ethylhexyl)benzo]-18-crown-6. The distribution ratios obtained with this compound in undiluted tri-n-butyl phosphate (TBP) compare favorably with those reported for synergistic systems combining a crown ether with the anion of a lipophilic organic acid.

ISSN:0736-6299    

DOI:10.1080/07366299608918345

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

An experiment on actinide partitioning from real high level waste (HLW) was performed in a continuous process by extraction with diisodecylphosphoric acid (DIDPA) using a battery of 12 centrifugal extractors installed in a hot cell. The HNO3concentration of the HLW was adjusted to 0.5 M by dilution. The extraction section had 8 stages, and H2O2was added to extract Np effectively. After extraction, Am and Cm were back-extracted with 4 M HNO3in 4 stages and Np and Pu were stripped with 0.8 M H2C2O4in 8 stages.

ISSN:0736-6299    

DOI:10.1080/07366299608918346

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Solvent extraction studies of99TcO4−and its nonradioactive congener ReO4−into 1,3-diisopropylbenzene and several other organic solvents containing the 0.200 M Aliquat-336 nitrate (which is predominantly methyltrioctylammonium nitrate) from a variety of aqueous solutions led to the following conclusions: (i) ReO4−is a suitable solvent extraction surrogate for99TcO4−under conditions that model nuclear waste streams at the DOE Hanford site; (ii) distribution ratios (D values) greater than 100 can be achieved for TcO4−extraction from aqueous solutions containing a mixture of 1 M NaOH and 1.5 M NaNO; (iii) the addition of 1.5 M NaNO2or 0.14 M K2CrO4to the aqueous phase containing a mixture of 1 M NaOH and 1.5 M NaNO3does not significantly affect D(TcO4−); (iv) D(TcO4−) values were larger by a factor of 3-5 when ketone solvents with flash points above 60°C were substituted for 1,3-diisopropylbenzene. Initial and final concentrations of TcO4−- in the organic and aqueous phases were determined by γ counting of solutions of99TcO4−that contained tracer amounts of95mTcO4−(0.204 MeV). Initial and final concentrations of ReO4−in the aqueous phase were determined by ICP-AES.

ISSN:0736-6299    

DOI:10.1080/07366299608918347

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Some new organoarsenic ligands were synthesized to investigate their potential as separating agents for trivalent lanthanide ions. Organofluoro-substituents were employed to improve the acid strength of new arsonic and arsinic acids to enable these to complex the metal ions in the lower pH region. Existing synthetic methods of simple alkyl and aryl derivatives of arsonic and arsinic acids were reviewed, modified and combined in order to prepare larger bulkier analogues with potential as extractants.

ISSN:0736-6299    

DOI:10.1080/07366299608918348

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper reports a novel approach for the evaluation of the stoichiometry of the metal-solvate formed during the macro level extraction of metal salts from neutral media by neutral solvating type extractants. This method involves the measurement of the distribution coefficient for the extraction of the metal ion from neutral medium as a function of the concentration of the metal ion in the organic phase, and finding the organic loading at which the distribution coefficient is a maximum. This new approach has been verified by a study of the uranyl nitrate extraction by tri-n-butyl phosphate and di-n-butyl octanamide, as well as cerium(lll) nitrate extraction by TBP. In all these cases the solvation number measured by the new method was in agreement with the value reported by other techniques. The method was extended to a study of the thorium nitrate extraction by trialkyl phosphates, which yielded a solvation number of 3 for all the trialkyl phosphates studied.

ISSN:0736-6299    

DOI:10.1080/07366299608918349

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The extraction equilibrium of sodium ion with 25,27-bis(carboxymethoxy)-26,28-bis(carboxyprorx3xy)-5,11,17,23-tetrakis(l,l,3,3-tetramethvlbutyl)calix[4]-arene and 25,26,27,28-tetrakis(carboxymethoxy)-5,ll,17,23-tetrakis(l,l,3,3-tetramethylbutyl)calix[4]arene has been studied by means of 'H-NMR spectrometry. The extraction equilibria of copper (II) ion with the above extractants have also been investigated in the absence or presence of sodium ion to clarify the extraction mechanism and the effect of the coexisting sodium ion on copper ion.

ISSN:0736-6299    

DOI:10.1080/07366299608918350

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The extraction of tantalum(V) from aqueous oxalic solution with 3-hydroxy-2-methyl-1 -phenyl-4-pyridone (HX) dissolved in chloroform in the presence of an excess of thiocyanate and perchlorate ions was examined at different acidities and ionic strengths.

ISSN:0736-6299    

DOI:10.1080/07366299608918351

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Interfacial activity of 2-cthylhcxanoylbcn/oyl methane is discussed in systems containing hydrocarbon diluents. Semiempirical self-consistent field calculations arc used to study the structure of β-diketones and its monohydrates in gas phase. These calculations arc in a qualitative agreement with interfacial tension studies and suggest a well-organi/ed structure of 2-clhyIhcxanoy(benzoyl methane for adsorption and interfacial reaction in extraction systems.

ISSN:0736-6299    

DOI:10.1080/07366299608918352

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Ion exchange reaction of lithium ions on cubic tantalic acid (C-TaA) was studied on the basis of pH titration curve for Li+ at 30, 45 and 60°C. The selectivity coefficients were plotted against equivalent fraction of lithium ions in the exchanger at a given temperature, which refers to the Kielland plot The selectivity coefficient on C-TaA was independent of the equivalent fraction of lithium ions in the exchanger up to a certain point and then decreased rapidly due to a phase transition. The results indicate that the reaction was preceded by an ion exchange mechanism for early stage and then phase transition to the hexagonal system.

ISSN:0736-6299    

DOI:10.1080/07366299608918353

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The uptake of tri-, tetra- and hexa-valent actinides as well as of pertechnetate anions by some new multifunctional ion exchange resins has been investigated. The new resins, identified as Diphonix A, for anionic Diphonix, contain the same geminally substituted diphosphonic acid groups bonded to a styrenic-based polymer matrix as the regular Diphonix resin, plus strong base anion exchange groups such as the tetraalkylammonium (Diphonix A - Type 1 resins) or the quaternized pyridinium (Diphonix A - Type 2 resins) groups. Our uptake measurements have shown that the Type 2 Diphonix A resins are as effective as the regular Diphonix resin in the rapid uptake of actinides from acidic solutions, while at the same time sorbing pertechnetate anions in a manner comparable to existing commercial anion exchange resins. The failure of the Type 1 Diphonix A resins to perform equally well has been explained as a consequence of the mutual interaction of adjacent diphosphonic acid groups and tetraalkylammonium groups. Uptake data have also been obtained with Se(IV). The behavior of the Diphonix A resins toward Se(IV) uptake in acidic solutions is comparable to that of commercial anion exchange resins.

ISSN:0736-6299    

DOI:10.1080/07366299608918354

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor