摘要:

Extraction equilibrium data of gallium (III) from hydrochloric acid solutions with LIX 54 dissolved in kerosene were measured at 20 and 60°C. The extraction mechanism, as shown by lineal plots, involves the formation of Ga(LIX 54)3complexes. Extraction kinetics are much faster at higher temperatures.

ISSN:0736-6299    

DOI:10.1080/07366299308918185

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Cyanex 302 and Cyanex 301 are recently available solvent-extraction reagents, the major components of which are the mono- and dithiosubstituted analogs of bis(2,4,4-trimethylpentyl)phosphinic acid, respectively. Sulfur substitution in the phosphinic acid increases the acidity of the extractants, and makes them particularly suited to the extraction of soft Lewis acids. Sulfur-containing dialkylphosphoric-acid extractants previously developed, however, are known to be very susceptible to oxidation and decomposition. To evaluate the extents of reagent decomposition which could reasonably be expected under normal plant operating conditions, this study examines the hydrolytic, chemical and thermal stabilities of Cyanex 302 and Cyanex 301 when subjected to extreme experimental conditions and prolonged periods of exposure to sulfuric and nitric acids. It is observed that concentrated sulfuric acid has no long-term detrimental effect on either of these reagents, but that the strongly oxidizing nature of nitric acid causes rapid destruction of the reagents, even at low acid strengths and for short periods of time.

ISSN:0736-6299    

DOI:10.1080/07366299308918186

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Studies have been conducted on the sorption characteristics of palladium (II) from hydrochloric acid media with a macromolecular resin containing tri-n-octylamine (TOA). Sorption equilibrium of Pd (II) on the TOA-impregnated sorbent can be expressed by a simple ion-exchange reaction between a tetrachloro complex of Pd (II) in the aqueous phase and an amine salt in the sorbent as follows:

ISSN:0736-6299    

DOI:10.1080/07366299308918187

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The interaction of nitric acid in two—phase Bystems in the pH range with the extractant, N,N—N’,N’-octabutylimidodipho8photetramide (OBIPA) in toluene has been investigated using two—phase potentiometiic titrations. The data thus obtained were analysed by the ESTA library of programs which was designed for modelling solution equilibria in aqueous phases. The use of such a program in the analysis of two-phase potentiometric data is novel, and the feasibility and corrections needed to be applied are discussed. Gratifying results were obtained indicating that a program such as ESTA may indeed be used for two-phase systems. The extraction equilibrium constant for the formation of the (2HA.HNO3)ospecies was found to be 7.54 * 104. Constants could also be calculated for the dimerisation and the partition of the extractant between the two-phases. These were found to be 18.5 M1−and 1.92 * 102respectively. A water soluble, methyl analogue of OBIPA was used to calculate the acid dissociation constant (pKa) which wasfound to be 9.043.

ISSN:0736-6299    

DOI:10.1080/07366299308918188

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Two new symmetrical diamides, namely straight-chain alkyl substituted neutral tetra-butyl-malonamide(TBMA) and sterlcally hindered branched-chain alkyl substituted tetra-isobutyl malonamide(TIBMA) were synthesised, characterised and used for the extraction of U(VI) and Pu(IV) from nitric acid media into n-dodecane. Both the cations were found to be extracted as their disolvates. Interestingly TBMA extracted more efficiently than TIBMA but afforded poor selectivity for Pu/U separation. The thermodynamic parameters involved in the extraction, determined by the temperature variation method, indicated the reactions in all cases to be enthalpy favoured. Entropy was found to be counteracting the extraction of U(VI) and favouring the extraction of Pu(IV). The recovery of diamides from the loaded actinides could be easily accomplished by using dilute oxalic acid or dilute U(IV) as the strippant for Pu(IV) and using dilute Na2C03as that for U(VI).

ISSN:0736-6299    

DOI:10.1080/07366299308918189

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In this paper, the extraction reaction mechanism of isoleucine by D2EHPA-kerosene is studied using the slope and isomer series methods. The extraction equilibrium constants are calculated. The results show that the extracted complexes of isoleucine,H2AR*3HR and H2AR, are formed in the organic phase and prove the following extraction reactions:

ISSN:0736-6299    

DOI:10.1080/07366299308918190

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The extraction of the trivalent radioactive lantha-nides ( Ln) Pm and Gd from nitrate aqueous medium by 8-hydroxyquinoline ( HOX) and/or trilaurylamine ( TLA) trioctylamine ( TOA) tributylamine ( TBA),tripropylamine (TPA) or triallylamine (TAA ),L, in chloroform was investigated. The chemical formulae of the extracted organic phase species for both lanthanides were found Ln.NO3.( OX) for the chelate and Ln.NO3( OX)2.L for the adduct.The respective extraction and formation constants were evaluated. The synergic extraction of Pm and Gd by HOX-amine was investigated as a function of temperature. The thermodynamic parameters, free energy change, enthalpy change and entropy change were evaluated. The stoichiometry of the extracted organic phase species was established and the different data obtained were discussed.

ISSN:0736-6299    

DOI:10.1080/07366299308918191

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The effect of a commonly used modifier, isodecanol, on the cobalt(II) -chloride system with the tertiary diamine extractants N,N,N’ N’-tetra-n-octylethylenediamine (tetocen) and N,N-di-n-ocryl-2-(aminomethyl)pyridine (pyridioc) was studied. The diamine extractants behave as stronger bases, the extraction of cobalt(II) decreases and chelate extraction mode is enhanced as the alcohol concentration in benzene is increased. The observations have been discussed in terms of changes in the solubility parameter and dielectric constant of the diluent and the solvation energy and solubility of the solute.

ISSN:0736-6299    

DOI:10.1080/07366299308918192

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

By use of the modeling program SXLSQA, it has been possible to perform an extensive equilibrium analysis of the extraction of Mn(ll) from nitric acid by didodecylnaphthalene sulfonic acid (HDDNS) in combination with either ;-butylbenzo-15-crown-5 (tBB15C5) or r-buty!cyclohexano-15-crown-5 (IBC15C5) in toluene. Overall, only 1:1 metalxrown ether interactions have been found, and HDDNS acts both

ISSN:0736-6299    

DOI:10.1080/07366299308918193

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Solvent extraction of copper was carried out in a mechanically agitated vessel, using LIX-64N as the extractant. The dispersed organic phase of various drop sizes was fractionated with respect to size and subsequently each drop size interval was analyzed for its copper content using atomic absorption spectroscopy. These data, which are first such information to be reported, clearly show that the extent of copper transfer to tha organic phase strongly depends on the level of bath agitation and also on the drop size. Possible rate-controlling mechanisms were discussed in viaw of the existing theories, and a theoretical support of the experimental results was provided by performing a mass-transfer analysis.

ISSN:0736-6299    

DOI:10.1080/07366299308918194

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor