摘要:

The effect of some aliphatic sulphur-containing compounds on the solvent extraction of cadmium and zinc by representative carboxylic acids (HA) is described. Alkanethiols (RSH) were found to cause large synergistic shifts in the pH0.5values for the extraction of cadmium (up to 2.85 pH units for the addition of 0.25 M thiol to 0.25 M carboxylic acid), with much smaller shifts for zinc (up to 0.84 pH unit). With the isomeric C8-thiols, the extent of the shifts for both metals is greater for the straight-chain compound (R = n-octyl) than for branched-chain analogues (R = 2-ethylhexyl or 2-octyl). Smaller synergistic shifts were obtained with dialkyl sulphides (RSR), whereas with dialkyl disulphides (RS.SR) slight antagonistic shifts were found.

ISSN:0736-6299    

DOI:10.1080/07366299408918231

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The distribution process has been studied of metal complexes with 4, 5-dimethylimidazole, 4,5-diethylimidazole and 4,5-di-n-propyl-Imidazole from aqueous phase to organic solvents. The influence of the chain length of the alkyl substituent on extractability of the metal complexes with solvents of different polarity has been discussed. The 4,5-dlmethylimidazole complexes were excellently extracted with alcohols (benzyl alcohol and 2-butanol). Longer alkyl substituents (ethyl, propyl) enhanced extractibility of the complexes with solvents of weak electron-donor capacity such as benzene and chloroform. The organic extractants showed high selectivity. Each of the metals could selectively be extracted within different pH range of the aqueous phase.

ISSN:0736-6299    

DOI:10.1080/07366299408918232

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Composition, structure and interfacial activity of alkanal oximes and kinetics of copper extraction from chloride solutions are discussed. Semiempirical self-consistent field calculations are used to study the structure of alkanal oximes and their mono- and dihydrates. These calculations are in a qualitative agreement with the ratio of alkanal (Z)-and (E)-isomers, interfacial activity and kinetics data.

ISSN:0736-6299    

DOI:10.1080/07366299408918233

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper reports the data on the extraction of U(VI), Pu(IV) and Th(IV) from nitric acid by tri-isobutyl phosphate, tri-n-amyl phosphate, tri-isoamyl phosphate and tri-n-hexyl phosphate and provides a comparison of their extract ion behaviour with that of tri-n-butyl phosphate. Data on the third phase formation in the system Th(NO3)4−HNO3−1.1 M trialkyl phosphate/n-dodecane are also presented.

ISSN:0736-6299    

DOI:10.1080/07366299408918234

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A s imp1e and efficient procedure has been developed to quantitatively recover Pu from oxalate supernatant using a mixture of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and TBP in dodecane. Pu(IV) in the range of 6.9 to 34.6 mg/1 was quantitatively extracted into 0.2M CMPO + 1.2 M TBP in dodecane from an aqueous solution containing 3.0 M HNO3and 0.1 M H2C2O4. At such low concentrations of Pu, the distribution ratio (D) did not change but the increase in oxalic acid concentration drastically reduced these values. The variation in HNO3concentration at a fixed concentration of 0.2 M CMPO + 1.2 N TBP has shown a dramatic increase in the D values, being 0.3 at 1.0 M and >104at 7.5 M. The extraction was almost quantitative even at the aqueous to organic ratio of 10:1. Plutonium could be quantitatively recovered by (i) stripping with 0.5 M acetic acid and (ii) coprecipitating it directly from the organic phase with 0.3 M oxalic acid + 0.3 M calcium nitrate + sodium nitrite.∼92% of the Pu was found in the precipitate and ”∼7% in the supernatant. Using this procedure, Pu in a concentrated form (∼50 times), could be recovered from the oxalate supernatant solutions without recourse to the destruction of oxalate Ion. The slope of 2 from the plot of log D ve log [NO3−] and log [CMPO] respectively suggest the species in the organic phase to be PuC2O4(NO3)2. 2CMPO. The absorption spectral study of Pu(IV) confirmed the above observations.

ISSN:0736-6299    

DOI:10.1080/07366299408918235

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Ion-pair extraction with organoboronate has been investigated as a regenerable means of removal and recovery of multi -OH compounds from aqueous solution. The extractant utilized was 3-nltrophenylboronate (NPB−), paired with Aliquat 336 as cation (A336+). The solubility of 3-nitrophenylboronic acid (NPBA) in water at 25°C was measured as 0.45 ± 0.02 g/100 g H2O. The 1:1 complexation stability constant for 1,2-propanediol with NPB−was measured by the buffer-capacity method through the Antikainen model as 3.2, 2.3 and 1.95 mol/1−1at 25°, 35° and 44.8°C, respectively. The A336+NPB−ion pair was prepared by repeated washing of a mixture of Aliquat 336, NPBA and diluent with aqueous NaOH and then water. Equilibria were measured for extraction of fructose, glycerol, and sorbitol from aqueous solution Into the ion-pair extractant in a diluent of 2-ethylhexanol.

ISSN:0736-6299    

DOI:10.1080/07366299408918236

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Liquid-liquid and liquid-liquid-solid equilibria were measured for isopropanol-water-phosphate salt systems, namely mono-, di- and tri- sodium, potassium and ammonium phosphates. The results are presented in form of binodal curves and tie-lines at 20°C for L-L systems, and approximate solubility lines for L-L-S systems.

ISSN:0736-6299    

DOI:10.1080/07366299408918237

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A twin column model was developed for decontamination processes, employing solvent extraction chromatography operated in the breakthrough mode. The model combines the laws for mass transfer between phases with empirical approximations and reproducible experimental observations. A detector is placed between the two columns allowing the acquisition of a full chromatogram without exhausting the decontamination capacity of the unit. A procedure is described to optimize column capacity and decontamination factor.

ISSN:0736-6299    

DOI:10.1080/07366299408918238

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Several biomaterials derived from blue-green algae and cells and tissues from some higher plants were tested for their potential to remove metal ions from solutions at different pH. Most biomaterials displayed pH-dependent binding profiles for Cu(II), Al(III), and Au(III). However, fragments of culturedDatura innoxiacells showed pH-lndependent binding of Au(III) binding of over 97%. Other biomaterials also showed high affinity for Cu(II) and Au(III) at pH 5.0. These included freeze dried roots and stems of cattail plants [Typha latifolia], the leaves of tumble weeds [Salsola spp), alfalfa sprouts [Medicago sativa’, and sphagnum peat. Al(III) binding by most biomaterials was low. An exception to this observation was Al(III) binding to alfalfa sprouts. The highest binding capacities for copper were exhibited by sphagnum peat moss and alfalfa sprouts with 30 and 18 mg Cu/g biomaterial,

ISSN:0736-6299    

DOI:10.1080/07366299408918239

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In a process for the recovery of gold-cyanide with a weak-base resin, it is desirable that the resin should load gold at the natural pH of the leach liquor and be stripped by an aqueous alkali. The present work explores, for such a resin, the potential of a phenol-formaldehyde polymer matrix which, it was thought, would facilitate the stripping of gold. Unexpected loading behaviour of a resin with an imidazoline active group is rationalized from results obtained during its titration. It is concluded that a phenol-formaldehyde matrix might limit the upper pH at which a resin can load, and its effect on pH functionality will depend on the concentration of phenolic groups.

ISSN:0736-6299    

DOI:10.1080/07366299408918240

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor