摘要:

The synergistic enhancement in the extraction of trivalent actinides (Am and Cm) and some lanthanides by 2-bromodecanoic acid and different nitrogen-containing extractants was studied. The extraction by mixtures of 2-bromodecanoic acid and 2,2′:6′,2″-terpyridine or N,N′-dimethyl-N,N′-dicyclohexyltetradecyl malonamide (DMDCHTDMA) respectively, intert-butylbenzene (TBB) or hydrogenated tetrapropene (TPH), was investigated and compared with 2,4,6-tri-(2-pyridyl)-l,3,5-triazine (TPTZ) in synergy with 2-bromodecanoic acid. The synergistic enhancement and the separation factor between americium and europium was higher with the terpyridine mixture compared with the malonamide mixture. The separation factor between americium and europium from nitric acid (0·01 M) with terpyridine (0·02 M), 2-bromodecanoic acid (1 M ) in TBB was determined to be 7, while the separation factor for malonamide (0·1 M), 2-bromodecanoic acid (1 M) in TBB was approximately 3. This might indicate a more covalent character in the actinide-terpyridine complex than in the actinide-malonamide complex. The terpyridine was shown to be easily transferred to the aqueous phase when protonated and thus the protonation ability for terpyridine was investigated at different concentrations of terpyridine and 2-bromodecanoic acid. Studies to determine the stoichiometry

ISSN:0736-6299    

DOI:10.1080/07366299908934610

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The influence of di-n-butyl phosphoric acid (HDBP) upon extraction of uranium(VI) by tri-n-butyl phosphate (TBP) from 0·5–3·0 M nitric acid solutions has been studied. It has been shown that the uranium(VI) distribution coefficientDufor extraction by 1·1 M TBP in tri-decane or xylene is increased when HDBP is present in the organic phase. For iso-molar solutions of (TBP + HDBP) with a total concentration of 0·36 M, and Uranium(VI) aqueous concentration up to 10–20  g/1, a maximum value of Du is observed when TBP/HDBP =1; for higher U(VI) concentration the maximum gradually disappears, with Du growing monotonically with the HDBP content in the organic phase. Uranium(VI) absorption spectra for 1·1 M TBP in tri-decane or xylene, containing HDBP, provide evidence for the formation of compounds, of which composition is intermediate between uranyl nitrate - TBP disolvate and the U(VI) - HDBP complex. It is proposed that these intermediate compounds are UO2(NO3)2, HDBP.TBP and UO2(NO3)2(HDBP)2.

ISSN:0736-6299    

DOI:10.1080/07366299908934611

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The synergistic extraction of lanthanoids(III), Ln(III),i e., La, Sm, Tb, Tm and Lu, using 2-thenoyltrifluoroacetone (Htta) and nitrogen-containing neutral bidentate ligands (S),i.e., three ethylenedi-amine derivatives, such as N,N'-dimethylethylenediamine (dmen), N,N'-diethylethylenediamine (deen) and cis-l,2-cyclohexanediamine (chda), was studied in the benzene and aqueous system. The synergistic enhancement in these extraction systems was mainly attributed to the formation of an adduct, Ln(tta)3S, in the benzene phase. The variation of the adduct formation constants (βs,l) was discussed with the basicity of ligands and structure hindrance around the metal ion.

ISSN:0736-6299    

DOI:10.1080/07366299908934612

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The solvent extraction process of yttrium (HI) from nitrate media by di(2-ethylhexyl) phosphoric acid (D2EHPA, represented as HA) has been studied as a first step to accomplish the homogeneous precipitation of yttrium oxalate from an organic metal loaded D2EHPA solution. The analysis of liquid-liquid distribution data at low metal concentrations determined YA3.2HA as the only metal organic species formed during the extraction, with a formation constant of logβ = 16·410 ± 0·055. A polymerisation of such organic metal species was observed at high metal loading of the organic phase. A comparison of these results with previous studies carried out in chloride or perchlorate media reveals a strong influence of the aqueous medium on the metal species formed in the organic phase, affecting mostly the stoichiometry of such species. The homogeneous precipitation of yttrium as yttrium oxalate using oxalic acid has been carried out as direct recovery of the metal from the organic solution. The observed precipitation-stripping kinetics has been related to the formation of organic yttrium species. The acidity of the stripping solution and the

ISSN:0736-6299    

DOI:10.1080/07366299908934613

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A mathematical model to predict the extraction behavior of metal ion between a polymer gel and an aqueous solution was proposed. It consists of the Flory-Huggins formula for evaluating thermodynamically the physico-chemical properties of polymer gel, the modified Stokes-Einstein equation to evaluate the mass transfer rate of metal ion into polymer gel and the equation to evaluate the extraction equilibrium.

ISSN:0736-6299    

DOI:10.1080/07366299908934614

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The separation of palladium from platinum from aqueous hydrochloric acid solutions using pyrazole derivatives as extractants is described. The role of o donicity of the extractants, their stereochemistry and their behaviour in repetitive cycles are illustrated. Their Pd specificity in relation to Cu(II)and Fe(III) which are also present in the industrial feed solution is also indicated.

ISSN:0736-6299    

DOI:10.1080/07366299908934615

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Liquid-liquid extraction of Pd(II) from hydrochloric acid solutions using di-(2-ethylhexyl) thiophosphoric acid (DEHTPA or HL) dissolved in kerosene has been studied. The distribution equilibrium of DEHTPA between the aqueous phase and the organic phase was investigated by treating the data with the computer program LETAGROP-DISTR. The extraction of Pd(II) from HC1 solutions by DEHTPA was studied as a function of several variables: equilibration time, organic phase diluent, HC1 and DEHTPA concentrations as well as temperature. Experimental equilibrium data were analyzed numerically using the program LETAGROP-DISTR and the results showed that Pd(II) extraction can be explained assuming the formation of PdL2complexes in the organic phase. DEHTPA was found to be selective for Pd(II) against Pt(IV), Rh(HI), Cu(II), Fe(III) and Zn(II). The back-extraction of Pd(II) loaded in the organic phase using different stripping reagents is also reported.

ISSN:0736-6299    

DOI:10.1080/07366299908934616

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The extraction of Pd(II) from HC1 solutions by impregnated resins containing di-(2-ethylhexyl) thiophosphoric acid (DEHTPA or HL) on the Amberlite XAD2 polymeric support has been studied. Graphical and computer analysis with the program LETAGROP-DISTR demonstrated that the Pd(II) extraction can be explained by the formation of metal complexes in the resin phase having the composition PdL2(HL)2. DEHTPA/XAD2 resins extracted Pd(II) in the presence of other metals: Pt(IV), Rh(III), Cu(II), Fe(III) as well as Zn(II). The stripping of Pd(II) loaded on the organic phase and the lifetime of the resins were also investigated.

ISSN:0736-6299    

DOI:10.1080/07366299908934617

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The paper embodies the details on the extraction behaviour ofNi(II) along with Cr(III), Fe(ni), Mn(II), Co(II), Cu(II) and Zn(II) from sulfuric acid media employing Cyanex 301-toluene system. The effect of various parameters like concentration of acid, metal ion and extractant and nature of diluent on the extraction of Ni(II) has been studied. On the basis of the distribution data the extracting species has been proposed. The recycling capacity of the extractant has been assessed. Some binary and ternary separations have also been achieved. The practical utility of the extractant has been demonstrated by recovering Ni(II) from spent catalyst and electroplating bath residue.

ISSN:0736-6299    

DOI:10.1080/07366299908934618

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The effects of phenols as additives on the solvent extraction of titanium(IV) with acetylacetone in carbon tetrachloride have been investigated. Titanium(IV) is scarcely extracted with acetylacetone, and the extractability is lower than that of the other titanium group metals, zirconium(IV) and hafnium(IV). However, the extractability of titanium(IV) acety lacetonate is greatly enhanced in the presence of 3,5-dichlorophenol where titanium(IV) can be extracted quantitatively and better than zirconium(IV) or hafnium(IV). The effects of the phenols (3,5-dichlorophenol, 3,5-dimethylphenol, and 4-chlorophenol) are greater than that of benzoic acid, and the phenol with the lower pKavalue is more effective. From equilibrium analy sis on the extraction system using 3,5-dichlorophenol (Hdcp), it was found that one mole of titanium(IV) is extracted together with two moles of acetylacetone (Hacac) and one to three moles of the phenol; one of the extracted species is suggested to be Ti(acac)2(dcp)2Hdcp.

ISSN:0736-6299    

DOI:10.1080/07366299908934619

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor