摘要:

The distribution coefficients are reported for99TcO4on the nitrate form of Reillex™-HPQ anion exchange resin. The nitric acid concentration was varied from 10.0 M to 9.80 x 10-4M at 20°C with a nominal pertechnetate loading of <0.03 mole % resin. Equilibrium was attained in 30 minutes or less.

ISSN:0736-6299    

DOI:10.1080/07366299408918210

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0736-6299    

DOI:10.1080/07366299408918211

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0736-6299    

DOI:10.1080/07366299408918212

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The extraction of zinc and cadmium with bis(5‘-hydroxy-pyrazol-4’-oyljalkanes (“HL-n-LH”, n: number of methylene links), with and without TOPO, in chloroform, has been studied when possible. The formation of third phases and/or precipitates hinders a number of extractions with HL-n-LH alone: CdIIfor all extractants, ZnIIfor n < 7. The following species are extracted with cadmium: Cd(L-n-L) (TOPO)2for n = 5, 7 to 10, Cd(L-8-L)(TOPO), Cd(L-8-LH)2(TOPO)2, Cd(L-8-LH)2(TOPO), and with Zn: Zn(L-n-LH)2for n = 7 and 8, Zn(L-n-L) for n = 9 and 10, Zn(L-n-LH)2(TOPO) for n = 5 and 7, Zn(L-n-L) (TOPO) for n = 7 to 9. The polymethylene chain length effect upon the extraction processes is attributed to a relative destabilization of Zn(L-n-L) with respect to Zn(L-n-LH)2for short-chain ligands, and conversely, to a preferential solvation of Zn(L-n-LH)2(TOPO)xcomplexes by chloroform. The former may be due to some strain in the tetradentate ligand folded onto zinc. The latter is attributed to H-bond formation between the free -LH sites and the diluent. Compared with the parent compound 1-phenyl-3-methy1-4-benzoylpyrazol-5-ol the bis(acylpyrazolols) show a better Zn/Cd extraction selectivity.

ISSN:0736-6299    

DOI:10.1080/07366299408918213

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Solvent impregnated resins (SIR) containing di-(2-ethylhexyl)-phosphoric acid (DEHPA) were prepared by adsorption of the organophosphorous extractant into Amberlite XAD2 polymeric macroporous adsorbent. Extractant adsorption on the polymer was studied as a function of both the nature of the organic solution and the extractant concentration used. The retention and interactions of the extractant on the polymeric matrix was studied by FTIR spectroscopy.

ISSN:0736-6299    

DOI:10.1080/07366299408918214

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The extraction of Zn(II), Cu(II) and Cd(II) from nitrate solutions at 0.1 M ionic strength by impregnated resins containing di(2-ethylhexyl)phosphoric acid has been studied at 25 °C.

ISSN:0736-6299    

DOI:10.1080/07366299408918215

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Equilibrium measurements of palladium extraction by chloroform solutions of 7-substituted-8-hydroxyquinoline derivatives from aqueous chloride media demonstrated that palladium is extracted as the chelate PdQ2- The formation of the chelate PdQ2was also confirmed with direct spectroscopic analysis. The extraction equilibrium constants, Kexwere determined to be log Kegex=5.59 and 5.84 for TN 1911 (an unsaturated and sterically-hindered derivative) and TN 2336 (a saturated and sterically-free derivative) respectively. It was found that PdQ2exhibits an absorption band at 460 nm in chloroform. It was shown that palladium extraction is influenced by both the extractant concentration and reagent structure. The importance of steric over electronic effects with respect to metal extraction was discussed. The individual roles of palladium, proton and chloride ion concentration were demonstrated. It was found that palladium extraction is exothermic with an enthalpy change of -29.6 kj/mole. The influence of stripping agent composition with respect to metal stripping was investigated. The addition of MgCl2in the HC1 strip solution was found to enhance stripping performance.

ISSN:0736-6299    

DOI:10.1080/07366299408918216

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Extraction of tri-, tetra- and hexavalent metal ions by N, N-N',N'— octabutylimidodiphosphotetramide has been investigated. Imidodiphosphoryl extractants show promise for treatment of nuclear waste but the optimum extractant structure must still be determined. Extraction of rare earths was investigated using two—phase potentiometnc titrations as the more conventional slope analysis techniques could not be applied. The data thus obtained were analysed by the ESTA library of programs which was designed for modelling solution equilibria in aqueous phases. Results obtained showed that ESTA may be used for modelling two—phase systems providing corrections are made. Models were obtained for the extraction of Nd(III), Eu(III), Y(III) and Yb(III). Extraction equilibrium constants could be calculated as well as distribution ratios showing that imidodiphosphoryl extractants are promising as rare earth extractants. Extraction mechanisms

ISSN:0736-6299    

DOI:10.1080/07366299408918217

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The extraction of Ce(III) and Eu(III) by nitrobenzene solutions of bis-l,2-dicarbollylcobaltate anions in the presence of 18-crown-6 from aqueous solutions of nitric acid has been investigated. Distribution ratios, the protonization and exchange extraction constants for the investigated systems has been determined. The calculated values of distribution ratios D have been compared with experimental ones.

ISSN:0736-6299    

DOI:10.1080/07366299408918218

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The third phase formation was studied as a function ofn-octyl(phenyl)-N, N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and tri-M-butyl phosphate (TBP) concentrations and temperature in the extraction of nitric acid. The concentration fractions of CMPO and TBP in the second and the third phases were determined by gas chromatography. Both CMPO and TBP were found to be enriched in the third phase. The concentrations of nitric acid in the second and the third phases relatively agreed with the calculated concentrations based on the extraction equilibrium constants of nitric acid by CMPO and TBP. The extraction of Np with the third phase formation was also discussed.

ISSN:0736-6299    

DOI:10.1080/07366299408918219

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor