摘要:

The interaction of UOzzplusEu3plus, La3plusand Th4pluscomplexes of TTA with several crown ethers have been investigated in benzene and chloroform. The thermodynamic (AG, AH, AS) parameters were measured by extraction and by titration calorimetry. The hydration of the complexes were determined by Karl Fischer and fluorescence techniques. NMR (H-l and C-13) spectra were used to further clarify the nature of the complexes. These spectra indicated that the metal ion more often does not interact equally with all the ether oxygens and the “fit” of the cation to the CE cavity is not significant. The binding to the simple crowns by Ln(TTA)3and UOz(TTA)2follows the CE basicity sequence but with DChl8C6 and DB18C6, steric effects become more important. Such effects are important for Th(TTA)4interactions even in the interactions with the simple crown ether.

ISSN:0736-6299    

DOI:10.1080/07366299308918142

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The extraction of Eu(III) and Am(III) vas investigated from nitrate medium by mixtures of thenoyltrifluoroacetone (HTTA) vith the soft donor ligands trlphenylamine, (Ph N) trlphenylarsine, (Ph As) or trlphenylphosphlne, (Ph P). Enhancement of the extraction of both metal ions vas observed for HTTA mixed vith either Ph As or Ph P. For the tvo cations investigated, Ph P shoved a greater synergic effect than Ph As. It vas found that the chemical formula of the main extracted species Is H(OH) (TTA)4HTTA.L for extraction by HTTA mixed vith either llgand (L). No specific preference for the synergic extraction of Am(III) over Eu(III) vas observed. For the tvo systems investigated, the mixed formation constant, £, for Eu(III) vas found to be alvays higher than that for Am(III)

ISSN:0736-6299    

DOI:10.1080/07366299308918143

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The distribution of Ga(lll), Fe(lll), Fe(ll), Zn(ll), Mo(VI) and V(V) between solutions of tributyl phosphate in dodecane and aqueous HCi solutions was investigated. To determine the composition of the extracted complexes, the results were treated in terms of thermodynamic activities in the aqueous phase. Possibilities of separating gallium from potentially accompanying elements were assesed.

ISSN:0736-6299    

DOI:10.1080/07366299308918144

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The solvent extraction of Au(III) from hydrochloric acid solutions by N-(thiocarbamoyl)benzamidines in chloroform has been studied. The distribution of gold has been determined at constant ionic strength of 0.1 ((K/ H')NO3-) as a function of pH and the analytical concentrations of extractant and chloride. The equilibrium data have been treated by means of the programs EXMAR and LETAGROP-DISTR. The data analysis indicates the formation of the species AuCl4HL and Au3C. In case of 4,4'-biphenyl-bis-{N-[N"-(diethyl)aminothiocarbonyl]-benzamidine}2:1

ISSN:0736-6299    

DOI:10.1080/07366299308918145

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Synergistic extraction of Fe(ITI) from H2SO4solutions, with a maximum at 130-150 g/1 H3SO4, is observed when using mixtures of Kelex 100 with di-alkyl phosphorus (HR) acids: D2EHPA, PC-88A, or Cyanex 272. No synergism, however, is observed when Kelex 100-M2EHPA mixtures are used

ISSN:0736-6299    

DOI:10.1080/07366299308918146

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Equilibrium and kinetic studies have been carried out on the extraction of nickel from sulfate solutions using bis(2,2,4 trimethylpentyl) phosphinic acid HDTMPP, “Cyanex 272tm”- It was found that nickel extraction in HDTMPP was favored by the presence of sodium in the organic phase and that equilibrium nickel concentration could be written in terms of the pre-equilibrated extractant concentration

ISSN:0736-6299    

DOI:10.1080/07366299308918147

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In the present study the extraction kinetics of cobaJt(II) ions with dithizone was investigated both in a buffer-free system and in a system with citric acid as auxiliary complexing agent in the aqueous phase. Through the combination of experiments in the stirred cell and with swarms of droplets it could be concluded that the rate-limiting-steps in both systems take place at the interface. The introduction of citric acid into the aqueous phase led to the formation of complexes of cobalt(II) ions with citrate. The presence of these complexes led to a change of the extraction kinetics as well as to a change of the extraction rate.

ISSN:0736-6299    

DOI:10.1080/07366299308918148

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A cryptomelane-type hydrous manganese dioxide in the H+form has been studied for its ion-exchange selectivity for Li+, Na+, K+, Rb+ and Cs+/H+ exchange at 30*C. The distribution coefficients for each alkali cation were calculated as a function of the initial concentration of exchanging cations in the presence of a constant total normality of 0.1 N. The separation factor for the Na+ - K+ pair attained 1.3 x 10" at Xx→0 This extremely high selectivity can be attributed to the rigid tunnel structure with an opening which is only accessible to less hydrated cations, those that shed their hydration shell easily and those with crystal ionic radius of approximately 1.4A.

ISSN:0736-6299    

DOI:10.1080/07366299308918149

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The distribution coefficients of sodium and potassium ions on crystalline dihydrogen tetratitanate hydrate fibers, were determined at 298, 313, 333, and 353 K as a function of pH. The adsorption behavior of the two metal ions was well explained by their ion-exchange reaction with hydrogen-ions in the fibers. The ion separation of sodium and potassium ions was successful by using a column of this ion exchanger with hydrochloric acid solutions as an eluent.

ISSN:0736-6299    

DOI:10.1080/07366299308918150

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor