Synergistic Extraction of Cobalt(II) by Mixtures of Bis(2-Ethylhexyl)Phosphoric Acid and LIX 860

The extraction of Co(II) from 1.0 M KNO₃ medium by mixtures of HDEHP (bis-2-ethylhexylphosphoric acid) and LIX 860 (5-dodecylsalicylaldoxime) dissolved in toluene has been studied. The effects of pH, metal, and extractant mixture concentrations on the extraction behavior have been examined. Synergistic extraction of the metal ion with the binary mixture of extractants has been found. Experimental results have been treated graphically and numerically by means of the Letagrop-Distr program and can be explained by assuming the extraction of two mixed complexes of general stoichiometry CoR₂(HR)(HL) and CoR₂(HR)(HL)₃, HR being bis-2-ethylhexylphosphoric acid and HL standing for 5-dodecylsalicylaldoxime. The corresponding extraction constant values have also been determined.     

二（2—乙基己基）磷酸萃取L—异亮氨酸的研究

以二（２－乙基己基）磷酸（Ｄ２ＥＨＰＡ）－正辛烷及Ｄ２ＥＨＰＡ－正辛醇萃取Ｌ－异亮氨酸为对象,研究了Ｄ２ＥＨＰＡ浓度、Ｌ－异亮氨酸初始浓度以及ｐＨ值对萃取平衡分配系数的影响。结果表明,在实验研究涉及的ｐＨ值范围内,分配系数先随ｐＨ的增加而增大,在３．５〈ｐＨ〈５区域,ｐＨ值对分配系数的影响较小。分配系数还随Ｄ２ＥＨＰＡ浓度的增加而增大。正辛醇加入有机相,萃取分配系数增大。Ｄ２ＥＨＰＡ与Ｌ－异亮氨酸     

Solvent Extraction of Alkali Metal Cations from Aqueous Solutions by Crown Ether Carboxylic Acids

Abstract

Competitive solvent extractions of alkali metal cations from aqueous solutions by the crown ether carboxylic acids sym-dibenzo-13-crown-4-oxyacetic acid, 2; sym-dibenzo-19-crown-6-oxyacetic acid, 3, and sym-dibenzo-14-crown-4-oxyacetic acid, 4, in chloroform have been conducted. Influences of aqueous phase pH and metal ion concentrations upon the concentrations of metals and complexing agent in the organic phase are assessed and compared with those reported for sym-dibenzo-16-crown-5-oxyacetic acid, 1. Extraction selectivity orders of K > Rb > Na ≈ Cs > Li, K > Rb ≥ Na ≈ Cs > Li, and K > Na > Rb > Cs ≈ Li were found for extractions using 2, 3, and 4, respectively. In terms of selectivity and metal extractability, 3 surpasses 1, 2, and 4.     

Synergistic Effects in the Extraction of Uranium(VI) by Di-4-octylphenyl Phosphoric Acid

Abstract

The extraction of uranium(VI) from sulfuric acid solutions by di-4-octylphenyl phosphoric acid (DOPPA) is enhanced by the addition of neutral organophosphorus compounds due to synergistic action. The effect of tri-n-butyl phosphate (TBP), dibutylbutyl phosphonate (DBBP), and tri-n-octyl phosphine oxide (TOPO) was studied. The synergistic effect increased in this order. In the case of TBP and DBBP the extraction coefficient for U(VI) decreased with increasing concentration of synergistic agent after reaching a maximum. With TOPO, on the other hand, there was an increase even after this limit. This was because of the extraction of uranium by TOPO itself. The effect of uranium loading in the organic phase on the synergistic behavior was studied and the results were compared with those obtained with di-2-ethylhexyl phosphoric acid (DEHPA) in the presence of the same synergistic agents. The results with these two extractants indicate that with TOPO the synergism is mainly due to the formation of substitution products of the type UO₂A₂B₂ and with TBP addition products of the type UO₂(HA₂)₂B.     

Analysis of Cobalt Extraction by DI-(2-Ethylhexyl) Phosphoric Acid in a Continuous Flow Stirred Tank with a Laser Capillary Spectro-Photometer

Abstract

A laser capillary spectrophotometric technique is used to study and quantify the dispersed phase mixing effects on the performance of a one liter continuous flow reactor for the cobalt-di-(2-ethylhexyl) phosphoric acid extraction system. Bivariate. distribution data show that, as the RPM increases, the drop size and drop concentrations change from widely to narrowly distributed, the former tending toward small drop sizes and the latter tending toward higher concentrations. Comparisons between the Monte Carlo simulation model predictions and experimental results, using an aqueous film reaction model, indicates that the simulation predicts the size distribution closely, the Sauter mean diameter within 10% error, and the extraction efficiency within 15% error.     

Extraction Behavior of Am(III) and Eu(III) from Nitric Acid Medium in Tetraoctyldiglycolamide-Bis(2-Ethylhexyl)Phosphoric Acid Solution

The extraction behavior of Am(III) and Eu(III) in a solution of tetra-octyldiglycolamide (TODGA), bis(2-ethylhexyl)phosphoric acid (HDEHP), and n-dodecane (n-DD) was studied to understand the role of TODGA and HDEHP in the combined solvent system. The extraction behavior of these metal ions was compared with those observed in TODGA/n-DD and HDEHP/n-DD. The effect of various parameters such as concentrations of HNO₃, TODGA, and HDEHP on the distribution ratio of Am(III) and Eu(III) was studied. Synergistic extraction of both the metal ions observed at lower acidities (<2.0 M) was attributed to the involvement of TODGA and HDEHP for extraction. However, the extraction of Am(III) and Eu(III) in the combined solvent was comparable with that observed in TODGA at higher acidities. The slope analysis of the extraction data confirmed the involvement of both the extractants at all acidities investigated in the present study.     

Studies on the Separation and Recovery of Uranium from Phosphoric Acid Medium Using a Synergistic Mixture of (2-Ethylhexyl)phosphonic Acid Mono 2-Ethyl Hexyl Ester (PC-88A) and Tri-n-octylphosphine Oxide (TOPO)

This paper deals with studies on the extraction of uranium(VI) from phosphoric acid medium using (2-ethylhexyl)phosphonic acid mono 2-ethylhexyl ester and tri-n-octylphosphine oxide individually as well as from their synergistic mixture. Different extraction parameters were investigated. With an increase in phosphoric acid concentration in the aqueous phase, the distribution ratio (Du) was found to decrease in all the cases. Synergism was observed when a mixture of PC-88A and TOPO was used. The synergistic mixture in the mole ratio of 4:1 (1.80 M PC-88A: 0.45 M TOPO) in xylene was found to be most suitable for uranium extraction. Among the various strip liquors used, 5% (w/v) solution of (NH₄)₂CO₃ was found to be the most suitable. Using a mixture of 1.8 M PC-88A and 0.45 M TOPO as the extractant system and 0.5 M ammonium carbonate as the stripping agent, uranium recovery was found to be better than 97% ± 3% in multiple contacts, (n = 2) from actual Davies Gray Waste while in case of wet phosphoric acid more than 52% ± 3% (n = 3) only could be recovered where n is the number of contacts.     

Extraction of Alkali Metal Tetraphenylborates by Polyurethane Foam

Abstract

The extraction of alkali metal tetraphenylborates by polyurethane foam was investigated. The extractability sequences are K⁺ ≈ Rb⁺ > Cs⁺ and K⁺ ≈ Rb⁺ ≈ Cs⁺ for polyether and polyester foams, respectively. The high extraction of K⁺ by polyether foam can be explained by the cation chelation mechanism.     

Uranium and Plutonium Extraction from Nitric Acid by N,N-Di(2-Ethylhexyl)-2,2-Dimethylpropanamide (DEHDMPA) and N,N-Di(2-Ethylhexyl)Butanamide (DEHBA) using Mixer-Settler Extractors

Extraction properties of N,N-di(2-ethylhexyl)-2,2-dimethylpropanamide (DEHDMPA) for nitric acid, U(VI), and Pu(IV) were studied by a batch method using various nitric acid concentrations. The distribution ratio equations for nitric acid, U(VI), and Pu(IV) were derived. A continuous counter-current experiment was performed using mixer-settler extractors to determine the performance of a process that uses two types of monoamides, DEHDMPA and N,N-di(2-ethylhexyl)butanamide (DEHBA), as extractants. This process consisted of two cycles: one dedicated to extraction of U(VI) by DEHDMPA, and the other dedicated to the co-extraction of U(VI) and Pu(IV) by DEHBA. The feed solution used for the continuous counter-current experiment was 4 mol/dm³ nitric acid containing U(VI), Pu(IV), and simulated fission products. DEHDMPA exclusively extracted U(VI) from the feed at the 1st cycle, and the ratio of U recovered in the U fraction stream was 99.93%. The residual U and almost all Pu were extracted by DEHBA in the 2nd cycle, and the recovery of Pu in the U-Pu fraction stream was 99.94%. Concentration profiles of U and Pu in mixer-settlers were calculated using a simulation code, which confirmed that the calculation was effective for estimating the U concentration in the U fraction stream, and the U and Pu concentrations in the U-Pu fraction stream.     

Synergistic Extraction Studies Using n-Octyl(Phenyl) N,N-Diisobutylcarbamoyl-Methylphosphine Oxide

Abstract

The effectiveness of n-octyl(phenyl)-N,N′-diisobutylcarbamoyl-methylphosphine oxide, CMPO, as a neutral extractant for the trivalent actinides and lanthanides from strong acid media has been well established. This investigation characterized the use of CMPO as a synergistic agent in the extraction of Am(III) and Eu(III) by thenoyltrifluoroacetone (HTTA). The distributions of the metal ions were measured using radiotracer techniques as functions of HTTA concentration, CMPO concentration and pH. The results show that the presence of CMPO enhances the extraction of Eu(III) and Am(III) by 10⁸. The synergistic adduct was M(TTA)₃·CMPO with no indication of higher complexes being formed. Unlike previous studies, the extraction of Eu(III) was more strongly enhanced than that of Am(III). The results showed little, if any, enhancement in the extraction efficiency due to the bidentate nature of the CMPO.     

异戊醇从氧化物-磷酸体系中萃取磷酸的动力学研究

采用上升液滴法研究了异戊醇从氯化物－磷酸体系中萃取磷酸的动力学，结果表明磷酸的初始正向萃取速率随两相界面积、水相初始磷酸、盐酸浓度的增大而增大，异戊醇对磷酸的萃取可能属扩散控制模式。在实验基础上建立了如下的萃取动力学方程：Ｒｐ＝４．７１９×１０－８Ｃ１．８０２ｐＣ１．００４ｃｌ，其计算值与实验值的相对标准偏差为５．０２％。     

The Possibility for Separation of Lanthanum by Solid-State Complexes with 2-Ethylhexyl Phosphoric Acids

Abstract

The elemental composition, molecule, and crystal structure of precipitates obtained from an acetone solution of Ln(NO₃)₃ (Ln = Pr + Er or La + Nd) with a mixture of bis- and mono-(2-ethylhexyl) phosphoric acids and their sodium salts were studied. In this study we found enrichment of the precipitate with the heavier lanthanide. The separation factor for the La-Nd couple is much greater than for the Er-Pr couple, and decreases with increasing rare-earth yield in the precipitate. We discuss the significant role of the stability of LnA₃ against HNO₃, especially the formation of La complexes with mono-(2-ethylhexyl) phosphoric acid during enrichment.     

Distribution Behavior of Amino Acid by Extraction with Di(2-ethylhexyl) Phosphoric Acid

Abstract

The distribution equilibrium of l-tryptophan (l-Trp) by extraction with di(2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in n-hexane was studied. The effects of L-Trp and D2EHPA concentrations, pH, and ionic strength, particularly of L-Trp loading in the organic phase, on extraction equilibrium were examined in detail. When the amino acid loading ratio (the molar concentration ratio of the equilibrium amino acid in the organic phase to the initial dimeric D2EHPA) was less than 3 × 10^?3, one L-Trp molecule was extracted by forming a complex with four monomeric D2EHPA molecules, and the extraction equilibrium constant (K _e) was determined to be 0.045 dm³/mol. Above this loading ratio the equilibrium formula did not hold, and the apparent equilibrium constant (K _a) increased significantly with increasing loading ratio. The phenomenon was explained by taking into account two parallel reactions in which fewer D2EHPA molecules, two and one respectively, were needed to extract one l-Trp molecule.     

Membrane Extraction of Ag(I), Co(II), Cu(II), Pb(II), and Zn(II) Ions with Di(2-Ethylhexyl)phosphoric Acid under Conditions of Electrodialysis with Metal Electrodeposition

Theoretical Foundations of Chemical Engineering - New methods for extracting cobalt and zinc ions from sulfuric acid solutions, of silver and lead ions from nitric acid solutions, and of copper...     

Extraction Equilibria of 4-Hydroxypyridine using Di (2-ethylhexyl) Phosphoric Acid

Extractions of 4-Hydroxpyridine (4HP) from aqueous solutions using Di(2-ethylhexyl)phosphoric acid (D2EHPA) as extractant in 1-octanol and kerosene were studied. The factors that affected the distribution coefficient (D), such as equilibrium pH, the concentration of D2EHPA, and the type of diluents were discussed. The interaction mechanism between 4HP and D2EHPA was validated by infrared spectroscopic analysis. D increased with the increase of the concentration of D2EHPA and peak values appeared at equilibrium pH = 3.6–5.0. D in the polar diluent (1-octanol) was much higher than those in the non-polar diluent (kerosene). The extraction reaction was found to be a proton-transfer process and D2EHPA mainly reacted through its –OH with –N– of 4HP. The apparent reactive extraction equilibrium constants K ₁₁ and K ₁₂ were obtained by fitting the experimental data of extraction equilibrium. By comparing calculated D values from the proposed model with the experimental ones, the accuracy of the proposed model was examined.     

Removal of Toxic Metal Ions from Metal-Finishing Wastewater by Solvent Extraction

Abstract

Solvent extraction procedures are presented for the removal of chromium, cadmium, and zinc from metal-finishing wastewater. The procedures utilize a 25% Alamine 336-xylene solution as the extractant. The three metals can be extracted selectively or simultaneously using a 100 to 1 aqueous phase to organic phase ratio. All three metals can be stripped from the organic phase with better than 99.5% efficiency with 4 M NaOH. The regenerated reagent can be recycled and reused without any loss of extraction efficiency. The procedures are reproducible, rapid, and simple.     

Solvent Extraction and Spectrophotometric Studies on Synergistic Extraction of Plutonium(IV) by Mixtures of Thenoyltrifluoroacetone (HTTA) and Tri-n-butylphosphate (TBP) in Benzene

Abstract

The synergistic extraction of Pu(IV) from perchloric acid solutions into mixtures of thenoyltrifluoroacetone (HTTA) and tri-n-butylphosphate (TBP) in benzene was investigated by solvent extraction methods. The adduct responsible for synergism was found to be Pu(TTA)₄·TBP. The adduct formation between Pu(TTA)₄ and TBP in the benzene phase was also investigated by spectrophotometry. The equilibrium constants for the equilibria involved were obtained both by solvent extraction and by spectrophotometric methods.     

Transport of Co(II) Ions through Di(2-ethylhexyl) Phosphoric Acid-CCl4 Supported Liquid Membranes

Abstract

A liquid membrane transport study of Co(II) using di(2-ethylhexyl) phosphoric acid (D2EPHA) as carrier and CCl₄, as diluent supported on polypropylene microporous film has been carried out. The carrier concentration in the membrane and HCl concentration in the stripping phase have been varied to see the effect on transport of Co(II) ions across the membrane. Maximum flux and permeability values of 1.23 × 10^?5 mol · m^?2 · s^?1 and 7.66 × 10^?11 m²/s, respectively, at a 0.87 mol/dm³ carrier concentration in the membrane have been found. At 1 mol/dm³ HCl concentration in the stripping phase the flux and permeability have maximum values of 1.4 mol · m^?2 · s^?1 and 5.27 × 10^?11 m²/s, respectively. The distribution coefficient of Co(II) ions into organic phase has been found to increase with increasing carrier concentration. The diffusion coefficient determined varies from 13.73 × 10^?11 to 0.83 × 10^?11 m²/s, which is the reverse order of the values of the distribution coefficient and explains the permeability of the Co(II) D2EPHA complex through the membrane.     

Purification of Unrefined Nickel(II) Sulfate Solution by a Continuous Countercurrent Multistage Extraction with bis(2-Ethylhexyl)phosphinic Acid

Separation of cobalt(II) and nickel(II) using bis(2-ethylhexyl)phosphinic acid as an extractant has been investigated by a liquid–liquid and a continuous countercurrent extraction. For comparison, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester has also been used, and the results are discussed in terms of cobalt–nickel selectivity. Based on the results, a highly selective procedure using 20% bis(2-ethylhexyl)phosphinic acid in heptane has been proposed to separate zinc(II), copper(II), manganese(II), cadmium(II), magnesium(II) and cobalt(II) from nickel(II). The separation method has been successfully applied to purification of unrefined nickel(II) sulfate solutions. © 1997 SCI.