ISSN:0736-6299    

DOI:10.1080/07366298808917953

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Abstract The height equivalent to a theoretical stage (HETS) is estimated using one correlation to describe behavior for reciprocating speeds below the optimum point and a second expression to estimateHETSvalues for reciprocating speeds above it. These two equations are then combined to yield a generalized expression that is applicable in both regions and which can be used to predict the minimumHETSand the optimum reciprocating speed. The observed dependence on the operating parameters and the physical properties of the liquid/liquid system generally agree with those observed inHETScorrelations for pulse columns.

ISSN:0736-6299    

DOI:10.1080/07366298808917954

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

In order to extract precious metals from diluted aqueous solutions, lipophilic extracting gels have been prepared by swelling lipophilic polymers - polyvinylchloride (PVC) or cross-linked polybutadiene (BR) and poly(styrene-butadiene) (SBR) rubbers-with extracting solvents. The DC 18C6-A crown-ether-CHCl3-BR gel extracts M(CN)2anions (M = Ag, Au) from 0.1M K0H with the same extraction constant as in the conventional liquid-liquid system but the diffusion coefficient of the extracted species is decreased by the polymer. A tri-n-butyl phosphate (TBP) - PVC gel was used to extract AuCl4from 0.5M HC1 : high aqueous-organic volume ratios (until 1500) were possible giving high concentration factors (until 10% of the gel weight).The extraction of PtCl62−from 0.5 M HCl with tri-n-octylamine (TOA) - toluene or CHC13, - SBR gels was limited by the poor penetration of TOA in the gels and by losses of metal-loaded organic phase outside the gels : better results were obtained with TOA-TBP-PVC gels tested also as M(CN)2extracting gels.

ISSN:0736-6299    

DOI:10.1080/07366298808917955

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Extraction of metal ions from the aqueous-organic solution containing dimethyl formamide(DMF), dimethyl sulfoxide(DMSO) and acetonitrile(AN) was investigated by using di-2-ethylhexyl-phosphoric acid(D2EHPA) as an extractant. The organic phase was a binary solution of D2EHPA and n-hexane, or D2EHPA and toluene, while the polar phase was a three component solution of metal salt, non-aqueous solvent and water. The extracted metal ions were Cr(III), Fe(III), Al, Cu, Ni, Co(II), Mg and Ag.

ISSN:0736-6299    

DOI:10.1080/07366298808917956

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A linear polyether, 1, 13-bis[8-qulnoly]-l,4,7,10,13-pentaoxa-trldecane (K-5) and an aza-crown ether, 4,13-didodecyl-1,7,10,16-tetraoxadiazacyclooctadecane (K22DD) when combined with thenoyltrlfluoroacetone (HTTA) have been shown to exhibit a synergistic effect on the extraction of uranyl ion. The effects of the addition to the organic phase of K-5, K22DD, and tert-butylcyclohexyl-15-crown-5 (15-C-5) on the extraction of UO2+2by HTTA in chloroform from 0.5 M NaNO3at 25°C have been measured. The results indicate the extraction is enhanced by the formation of an adduct, UO2(TTA)2S for K-5 and K22DD. No enhancement of the extraction was seen with the crown ether. The organic phase stability constants for both K-5 and K22DD were evaluated and found to be similar in magnitude. These results suggest that the major factor in the formation of the synergistic adduct is the presence of the nitrogen atom in the synergist.

ISSN:0736-6299    

DOI:10.1080/07366298808917957

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The extraction of Pa(V) by both ph3PO and Ph3AsO in chloroform from HCl medium is performed. The extraction stoichiometry for each system is proposed which is assumed to proceed through the formation of monosolvate. The extraction behaviour of Pa(V) by both extractants is quantitatively described by an empirical equation for each case. The obtained data show that the extraction power of Ph3AsO is much higher than the corresponding value of PH3PO. This difference is ascribed to the difference in their electronic structure. The effect of using different diluents is studied. In the same way, the extraction of Th (IV) by both extractants from HCl medium is described and the separation factors for both systems are calculated and compared.

ISSN:0736-6299    

DOI:10.1080/07366298808917958

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The distribution of trace and macro amounts of Pu(IV) and Th(IV) chlorides between solutions of n-octyl(phenyl)-N,N-diiso-butylcarbamoylmethylphosphlne oxide in tetrachloroethylene and aqueous solutions of hydrochloric acid was studied. In extracting macro quantities of Pu(IV), the solvent can be loaded up to a Pu(IV)/extractant ratio of 1:2, but small amounts of a solid are formed which strongly retard phase disengagement. The disengaging problem can be overcome by using a phase modifier such as tributyl phosphate or dibutyl butylphosphonate. Both modifiers only slightly suppress the efficiency of the Pu(IV) extraction. Th(IV) is less extractable than Pu(IV) and a Th(IV) extractant ratio of only 1:3 can be reached even In the presence of excess Th(IV). Both Pu(IV) and Th(IV) form a third phase (second organic phase) at high concentrations of hydrochloric acid or in the presence of chlorides which salt-out hydrochloric acid from the aqueous phase.

ISSN:0736-6299    

DOI:10.1080/07366298808917959

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The Pitzer treatment is employed to estimate activity and osmotic coefficients for these aqueous mixtures from literature data. A convenient formalism is presented for the inclusion of electrically neutral species such as undissociated HNO3in the treatment. The water vapor pressure and the solubility of uranyl nitrate hexahydrate in HNO3could be fitted reasonably well with parameters derived from solutions of the separate components. Isopiestic data for NaNO3- UO2(NO3)2mixtures required one mixture parameter. Stoichiometric activity coefficients and water activities are generated for UO2(NO3)2- HNO3mixtures from the derived parameters.

ISSN:0736-6299    

DOI:10.1080/07366298808917960

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Distribution coefficients of 23 elements between chelating resin Duolite ES 346 containing amidoximo groups and glycine - HCl buffer /pH = 2 - 3.5/, acetate buffer /pH = 3.6 - 5.6/ and HCl solutions /0.05 - 12M/ respectively were measured by batch equilibration at tracer loadings. While alkali and alkaline earth metals are practically not retained by the resin, transition and other metal ions show quite differentiated pattern of selectivity. The resin exhibits amphoteric properties and in certain conditions both cations and anions can be simultaneously adsorbed. Selectivity reversal for some pairs of metal ions can be achieved employing either cation exchange or anion exchange function of Duolite ES 346. Quantitative separations of Zn-Fe, Cd-In, Zn-Hg, Co-Cu, Zn-Re-Ga and Pt-Pd mixtures with the use of short columns of the resin have been demonstrated.

ISSN:0736-6299    

DOI:10.1080/07366298808917961

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Phosphate sorption on the strong basic anion exchanger Amberlite IRA-400(Cl−form)is studied as a function of pH(3-11)and different initial concentration ranges (5-25 ppm,120-190 ppm)at 25°C. The ratio of chloride released /phosphate sorbed increases with the increase in pH and decrease with the increase in the concentration of the solution. It is suggested that phosphate sorption takes place initially as HPO2−4followed by H2PO−4. The data is explained with the help of Langmuir and mass law action equations.

ISSN:0736-6299    

DOI:10.1080/07366298808917962

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor