摘要:

Studies were performed with a mixture of commercial extractants (Alamine 336 + LIX 54) used for copper recovery from hydrochloric etching solutions to transfer copper from hydrochloric to sulfuric medium. The most appropriate ratio between the components of the extractant mixture was found. The separate steps of the process (extraction, scrubbing, stripping and conditioning) were optimized.

ISSN:0736-6299    

DOI:10.1080/07366299308918173

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Solvent extraction of Np with n -octyl ( pheny1) -N, N -diisobutylcarbamoylmethylphosphine oxide (CMPO) from HNO3solution containing H2O2was studied from the aspect of extraction rate. Neptunium initially in the pentavalent oxidation state can be extracted by CMPO even without the addition any redox agents, but the distribution is rather low. The H2O2was found to enhance the distribution ratio. The extraction rate was almost proportional to the 1.5-power of H2O2concentration. The dependence of the extraction rate on HNO3concentration was also examined. Reduction of Np(V) with H2O2occurs rapidly in the presence of CMPO. The extraction rate is not strongly affected by the presence of tri-n-butylphosphate in the organic phase. As a diluent, decalin gives a greater extraction rate than n-dodecane.

ISSN:0736-6299    

DOI:10.1080/07366299308918174

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The extraction of rhenium(vii) with benzo-15-crown-5 (B15C5) and dibenzo-18-crown-6 (DB1SC6) into 1,2-dichloroethane was investigated. The presence of K+, NH4+or Na+in aqueous phase was necessary for the extraction. The study showed that the Re(VII) was extracted by forming ion-pair compounds of [M+(B18C6][Re4-] and [M+(B15C5)n][ReO4−](M+= K+, NH4+. and Na+; n = 1-2). Effea of cationic crown ether complexes on extraction of RcO4-is discussed in terms of structure of extracted species. It was found that K+-B15C5 cation is the most efficient since K+forms hydrophobic 1:2 complex readily with B1SCS. Equilibrium constants (Kex) and thermodynamic quantities for these extraction reactions were determined. The Kexvalues decrease in the sequences of K+> NH4+> Na+and B15C5 > DB18C6. The thermodynamic measurement indicated that the extraction of ReO4−with cationic B15C5 and DB18C6 complexes was enthalpy driven. The different extraction behaviors between anion species and alkali picrates are discussed.

ISSN:0736-6299    

DOI:10.1080/07366299308918175

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Thermodynamic partition functions between water and heptane of the square-planar palladium bis-acetylacetonate and bis-2,4-hexanedionate were determined and compared with partition functions of the corresponding tetrahedral complexes of beryllium. Higher partition coefficients, less positive enthalpy and entropy of partition and lower salting-out coefficients of palladium complexes point to their less hydrophilic character. A plausible explanation is the hindered access of water molecules to ligand oxygen atoms in square-planar complexes.

ISSN:0736-6299    

DOI:10.1080/07366299308918176

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The extraction of Au(III) by tri-n-dodecylammonium chloride (TLAHCl) has been studied by measuring the distribution coefficient of the metal as a function of the TLAHCl concentration at 0·5, 1 and 2 ionic strength. Results indicate the formation of the species AuCl3(TLAHCl) and AuCl3(TLAHCl)2in the organic phase. The formation constants vary linearly with the ionic strength. By using the Specific Interaction Theory the interaction coefficient between AuCl4and H+has been estimated.

ISSN:0736-6299    

DOI:10.1080/07366299308918177

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Kinetic study of the extraction of palladium(D) with didodecylmonothiophosphoric acid in n-heptane diluent was carried out using a stirred transfer cell to clarify the extraction mechanism. The effect of surfactants on the kinetics of palladium extraction was also investigated, to elucidate the role of surfactants used in liquid surfactant membranes. Moreover, the interfacial tension between the organic and aqueous phases was measured to elucidate the adsorption equilibrium of the surfactants. It was found that the interfacial activity of each surfactant is higher than that of the extractant. In the kinetic study of palladium extraction, the experimental results of the extraction rate was analyzed by the interfacial reaction model, taking into account of the adsorption of the surfactant and extractant. The rate-determining step of palladium extraction was the complex formation between four chloro-palladium complexes and the extractant at the interface, and the extraction rate constants of each palladium species were obtained. The extraction rate of palladium in n-heptane diluent was much faster than that in toluene. Additionally, it was suggested that there was particular interaction between the surfactant and extractant at the interface. The effect of the surfactant on the extraction rate was explained by taking into account the adsorption of the surfactant at the interface.

ISSN:0736-6299    

DOI:10.1080/07366299308918178

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The limiting organic phase concentration (LOC) above which a third phase forms, in Thorium Nitrate - 30% TBP/Diluent system has been shown to have a good correlation with some parameters which characterise the diluent such as Connectivity Index, Wiener Number and Diluent Parameter. Aliphatic, alicyclic, aromatic and halocarbon type diluents have been used in this study. The LOC has also been found to be additive for mixtures of diluents. The results make it possible to predict third phase formation in systems where the diluent composition is known.

ISSN:0736-6299    

DOI:10.1080/07366299308918179

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Three commercially available chromatographic materials were tested in a column mode for use in separating Am, Pu, and™Sr from actual neutralized cladding removal waste (NCRW) taken from a Hanford waste tank. For these experiments, the NCRW was dissolved in HNO3/HF solutions. TRU-Spec™was evaluated for the separation of transuranic elements. TRU-Spec™removed Am and Pu from a dissolved NCRW solution, but not as effectively as the TRUEX solvent extraction process. Sr. Spec™and SuperLig™601 were evaluated for the separation of Sr, Sr- Spec™performed very well in the separation of SK from dissolved NCRW solution; Sr was not detectable in the column effluent after six bed volumes of solution had been passed through the column. SuperLig™601 was less effective than Sr- Spec™at separating Sr from dissolved NCRW solution under the conditions used in this experiment. The poor performance of SuperLig Spec™601 has been attributed to slow kinetics of absorption of Sr.

ISSN:0736-6299    

DOI:10.1080/07366299308918180

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The ion exchange of trace amounts of Cu2+, Zn2+and Pb2+with the hydrogen-form of hydrated ferric oxide as a function of nitric acid concentration has been studied at 25, 30,35 and 60°C. Ion exchange of these cations increases with increasing temperature in the investigated temperature range. From these results, equilibrium constants for the Cu2+/H+, Zn2+/H+and Pb2+/H+ion exchange on hydrated ferric oxide and thermodynamic quantities for these reactions were calculated, and some predictions made for the exchange process taking place in this material. The selectivity series is Zn2+> Cu2+> Pb2+.

ISSN:0736-6299    

DOI:10.1080/07366299308918181

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Selectivity coefficients KHMfor trivalent metal ions / hydrogen ions (M3+/H+) exchanges on titanium antimonate cation exchanger (TiSbA) have been determined for group 13 metals (Al3+, Ga3+, and In3+) and rare earth metals (La3+, Nd3+, Eu3+, Yb3+, and Y3+) ions by batch equilibration at 30, 45, and 60°c in nitric acid media. Kielland plots (logKHMvs. the fractional exchange X¯M) for these exchange systems have been analyzed and found to show a break point at X¯M=0.005-0.01. This behavior can be interpreted assuming a two-site model. A site available at infinitesimal X¯Mvalue has a large steric effect. The selectivity in this site increased in the order: Al3+< Ga3+< In3+for group 13 metal ions and Y3+< Yb3+< Eu3+< Nd3+< La3+for rare earth metal ions in the X¯M<0.02 region at 30°C. The amounts of Ga3+exchanged by TiSbA increased with a rise in temperature. The selectivity of group 13 metal ions changed to: AI3+< In3+< Ga3+at60°C. On the other hand, the selectivity order for rare earth metal ions was independent of temperature. The hypothetical thermodynamic data (ΔGoideal, ΔHoidealand ΔSoideal) at 25°C were evaluated.

ISSN:0736-6299    

DOI:10.1080/07366299308918182

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor