摘要:

The extraction of thorium(IV) and uranium(VI) from nitric acid solutions into ligroine solutions of 2-ethylhexyl phenylphosphonic acid (HEHφP), micellar dinonyl naphthalene sulphonic acid (HDNNS) extractants and mixture of the two extractants is reported. A synergistic enhancement factor of 66.9 and 10.8 were observed for Th and U, respectively, when extracted from 1 M HNO3Although HDNNS shows better separation of thorium and uranium, the mixed ligand system exhibits superior extractability for both metals ions. Slope analysis method was used to establish the extraction stoichiometry. The extraction stoichiometry varies as the concentration of the micellar HDNNS in the organic phase and the acidity of the aqueous phase changes.

ISSN:0736-6299    

DOI:10.1080/07366299708934462

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Studies have been carried out on the effect of temperature on the extraction of U(VI) from nitric acid medium by tri-n-amyl phosphate/n-dodecane, measured as a function of the extractant concentration and aqueous phase acidity. The results indicate that the extraction is exothermic as in the case of tri-n-butyl phosphate. From the data available an effort has been made to calculate the equilibrium constant, the Gibbs energy change and the entropy change of the extraction reaction.

ISSN:0736-6299    

DOI:10.1080/07366299708934463

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The chemical model presented is founded on the prediction of all chemical reactions taking place in a solvent extraction system. Starting from equilibrium constant expressions of these chemical reactions the corresponding mathematical formulae for calculation of the concentrations of distributing species are derived. If the required chemical reactions in the organic phase are involved, the model fits the experimental data and enables the calculation of the concentrations of distributing species in the organic phase within the concentration range in which the distribution of reacting species was measured.

ISSN:0736-6299    

DOI:10.1080/07366299708934464

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Synergistic solvent extraction of trivalent lanthanides such as Nd, Eu and Tm has been studied using mixtures of 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) and 18-crown-6; 15-crown-5, benzo-15-crown-5, or dibenzo-18-crown-6. The results demonstrate that these trivalent metal ions are extracted into chloroform as Ln(PBI)3with HPBI alone and as Ln(PBI)3. CE in the presence of crown ethers (CE). The equilibrium constants of the above species are found to increase monotonically with the decreasing ionic radii of these trivalent lanthanides. The addition of a crown ether to the metal chelate system significantly enhances the extractability of these trivalent metal ions.

ISSN:0736-6299    

DOI:10.1080/07366299708934465

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Extraction of Pb from nitric acid solutions and simulated acidic hazardous waste streams has been demonstrated with 0.15 M 4',4',(5')-di-(t-butyldicyclohexo) 18-crown-6 and 1,2 M tributyl phosphate in a commercial isoparaffinic hydrocarbon called Isopar L*. The extraction has been shown to be dependent upon extractant concentration, aqueous nitrate concentration, and the identity of the predominant anion in the aqueous phase. It has been shown that Pb and Sr can be extracted simultaneously and stripped efficiently from the loaded organic phase. The quantitative (>99%) removal of Pb and Sr can be achieved in 3 to 4 batch contact extractions. Batch contact flowsheets have been utilized to demonstrate the potential for the simultaneous removal of Sr and Pb from simulated radioactive waste followed by partitioning of the extracted Sr fraction from the Pb fraction.

ISSN:0736-6299    

DOI:10.1080/07366299708934466

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The new extractant 2-(r-octylthiomethyl)pyridine was synthesized and applied in dilute acid medium in the presence of chloride and thiocyanate ions, for the separation of later 3d transition metal ions. Good Cu(II) specificity was revealed in dilute chloride medium as well as very promising nickel(II) preference to iron(III). The extractant behaviour of the ligand was explained in terms of its coordination behaviour.

ISSN:0736-6299    

DOI:10.1080/07366299708934467

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The extraction equilibria of Co(II) from 1·0 M KC1 medium by the commercial extractant Cyanex 302 (bis(2,4,4-trimethylpentyl)monothiophosphinic acid) dissolved in toluene has been studied. The effects of pH, extractant concentration and metal concentration on the extraction behaviour have been examined. The influence of bis(2,4,4,-trimethylpentyl)dithiophosphinic acid, one of the minor impurities of Cyanex 302 and also the major component in Cyanex 301 on the extraction of cobalt has also been considered. Experimental data have been treated graphically and numerically by means of the computer program LETAGROP-DISTR, and can be explained by assuming the extraction of the species CoR2(HR), CoR2(HR)2, CoL2and CoCIL(HL), HL being bis(2,4,4-tri-methylpentyl)dithiophosphinic acid and HR standing for bis(2,4,4-trimethylpentyl)-monothiophosphinic acid. Conditional equilibrium constants of the extraction process are also given.

ISSN:0736-6299    

DOI:10.1080/07366299708934468

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

p-(l,l,3,3-Tetramethylbutyl)phenyl hydrogen[N,N-di(2-ethylhexyl)amino-methylphosphonate was synthesized as a novel type of extractant to investigate the extraction behavior of base metals as well as of precious metals from aqueous chloride media into toluene. This reagent exhibited high selectivity for platinum (IV) and palladium (II) ions in the low acidic region (0·01 - 6 mol dm−3) / over base metal ions except for trivalent iron over the whole concentration region under the present experimental conditions. The extraction of platinum and palladium with p-( 1,1,3,3-tetramethylbutyl)phenyl hydrogen[N,N-di(2-ethylhexyl)aminomethyl-phosphonate was higher than that with N,N-di(2-ethylhexyl)aminomethyl-phosphonic acid due to its high lipophilicity. Stripping of the loaded palladium was achieved with an aqueous mixture of I mol dm−3thiourea in combination with I mol dm−3hydrochloric acid. The extraction reaction of palladium from aqueous chloride media into toluene was found by slope analysis to be described as follows

ISSN:0736-6299    

DOI:10.1080/07366299708934469

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Linear solvation energy relationships, based on application of Kamlet and Taft model, were used to predict the interfacial tension isotherms of l-(2'-hydroxy-5'-methylphenyl)-decane-l-oneoxime in the systems containing octane, toluene and their mixtures as model dilutes. The correlations found permit: (i) to predict the interfacial tension and surface pressure at given concentration of model extractant; (ii) to estimate A and B parameters in Szyszkowski equation and then to predict the whole adsorption isotherms in systems containing various amounts of toluene; (iii) to predict the surface excess for different concentration of extractant in each individual system. The linear solvation energy relationships enable also to formulate semiempirical equations for the interfacial tension, surface pressure and the surface excess isotherms which contain separated effects of extractant concentration and diluent properties.

ISSN:0736-6299    

DOI:10.1080/07366299708934470

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

In some industrial processes there are wastes of valuable elements, so it could be very important for the efficiency of the process to recover these elements. Recovery by ion exchange frequently presents the problem of the posterior extraction of the valuable elements by elution from the resin. One interesting solution appears when the eluent may be the raw material of the process that takes with it the product recovered. An example is the recovery of potassium from a fertilizer industrial wastewater at high ionic solution concentration coming from a crystallization process. When this is to be carried out, not only the high efficiency of counter-ion retention is a key factor, but also an adequate evolution of the co-ion component, since both are feed material of the main process. Design and simulation of this process, with low Donnan exclusion, requires a reliable model for the evolution of both counter- and co-ions in column operation of industrial interest, using the basic information of hydrodynamics and ion exchange characteristics. The work presented here shows the good applicability of this recovery coupling process, and the simulation of the column elution operation; a key part of the process. The simulation of the loading step was carried out in previous works. Simulation of some breakthrough curves are presented as example in this article.

ISSN:0736-6299    

DOI:10.1080/07366299708934471

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor