Synergistic extraction of uranyl ion with 1-phenyl-3-methyl-4-benzoylpyrazolone-5 (HPMBP) and diphenyl sulfoxide (DPSO), tri-n-butyl phosphate (TBP) or tri-n-octylphosphine oxide (TOPO)

Synergistic extraction of uranyl ion with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and oxo donors with widely varying basicity, viz. diphenyl sulfoxide (DPSO), tri-n-butyl phosphate (TBP) and tri-n-octylphosphine-oxide (TOPO) has been studied at various fixed temperatures. Results indicate that the equilibrium constants in the organic phase for addition reactions (K_S) with these donors follow their order of basicity (K_H) viz. DPSO (0.033)<TBP (0.16)TOPO (8.9) with log K_S values of 3.70, 4.28 and 6.45, respectively. The thermodynamic parameters associated with the formation of these systems have been evaluted by the temperature coefficient method. The results indicate that the complex in the organic phase for DPSO and TBP is stabilized only by enthalpy, whereas both enthalpy and entropy contribute to the stabilization of the TOPO complex. Also, enthalpy contribution is more prominent as compared with the UO ₂ ²⁺ /HTTA/TOPO system, where both enthalpy and entropy contribute almost equally.     

Extraction of U(VI) by phosphonic acid in the presence of neutral donors

Extraction of U(VI) by mixtures of 2-ethylhexyl 2-ethylhexylphosphonic acid (PC88A) and TOPO in cyclohexane and xylene from aqueous sulfuric acid medium has been investigated. Synergism was observed and the species responsible was identified as UO₂H₂Y₄.TOPO. From the data equilibrium constants for the various reaction equilibria at different temperatures and the thermodynamic parameters were calculated. Antagonism was observed when alkylamide or TBP was used as the neutral donor.     

Extraction equilibrium of ytterbium(III) with sulfoxides and their mixtures

The extraction equilibria of¹⁷⁵Yb from thiocyanate solutions with di-n-pentyl sulfoxide (DPSO), di-n-octyl sulfoxide (DOSO), tri-n-octylphosphine oxide (TOPO) and their mixtures in carbon tetrachloride has been investigated. A relatively small synergistic enhancement has been observed with mixtures of dialkyl sulfoxides (DPSO+DOSO) and also with mixtures of DPSO+TOPO. These extraction data have been analyzed with the aid of a computer by taking into account complexation of the metal in the aqueous phase by inorganic ligands and assuming a set of product species in the organic phase and adjusting their formation constants through an iterative non-linear least-squares procedure to obtain the best fit to the data. The extraction of the metal is inversely and linearly dependent upon the dielectric constant of the solvent and temperature of the system.     

Extraction of Re(VII) by neutral and basic extractants

The mechanism of Re(VII) extraction from sulphate-containing solutions using primary amine Primene JMT, trioctylphosphine oxide (TOPO), tributyl phosphate (TBP), and their mixtures was investigated. It was found that the ratio of Re(VII) with Primene JMT and its sulphate in the organic phase was 1:1. The composition of Re(VII) complexes with TOPO depended on the acidity of solution ranging from about 1:1 to 2:1. When the extraction was carried out by TBP the mole ratio of TBP to Re was approximately 4. Primene JMT proved to be the most suitable agent for Re(VII) extraction with the exception of strongly acidic solutions, in which TOPO provided better results. The mixed solvents Primene JMT and TOPO as well as Primene JMT and TBP presented a slight synergism in weakly acidic solutions. Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May 2006.     

Synergistic extraction of radium using 2-thenoyltrifluoroacetone and tributyl phosphate or trioctylphosphine oxide

The extraction of radium into a mixture of 2-thenoyltrifluoroacetone (HTTA) and tributyl phosphate (TBP) or trioctylphosphine oxide (TOPO) in n-hexane or cyclohexane has been investigated with regard to the dependence on pH, and TBP and TOPO concentrations. It has been found that the formation of mixed complexes of the type Ra(TTA)₂ (TBP)₂ and Ra(TTA)₂(TOPO)₂ occurs and the overall extraction constants of both complexes were calculated. With the systems described, very high distribution ratios of radium have been attained; these may advantageously be used for the separation and concentration of traces of radium.     

Extraction behavior of trivalent lanthanoids and yttrium with bis (2,4,4-trimethylpentyl)octylphosphine oxide

The extraction behavior of yttrium and trivalent lanthanoids has been investigated from thiocyanate solutions using bis(2,4,4-trimethylpentyl)octylphosphine oxide (CYANEX 925) in xylene as an extractant by tracer techniques. The results demonstrate that these trivalent metal ions are extracted as M(SCN)₃•3CYANEX 925. The equalibrium constants of the extracted complexes have been deduced by non-linear regression analysis. The extraction behavior of trivalent lanthanoids and yttrium was found to be ambiguous since the distribution ratios of these metal ions are nonmonotinic function of atomic number (La<Y<Pm<Tm<Ho<Eu<Yb<Lu). The separation factors between these trivalent metal ions have been calculated and compared with commercially important extraction systems like tributylphosphate (TBP), trioctylphosphine oxide (TOPO), octy(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and di-2-ethylhexyl phosphoric acid (DEHPA). The possibilities for separating yttrium from trivalent lanthanoids has also been discussed.     

The separation of zinc(II) and cadmium(II) by liquid-liquid extraction

The extraction of Zn(II) and Cd(II) from thiocyanate solutions with bis-2-ethylhexyl sulphoxide (B₂EHSO) in benzene as an extractant has been studied by tracer techniques. For comparison, extraction has also been carried out with tributylphosphate (TBP). The extraction data have been analysed by both graphical and theoretical methods by taking into account complexation of the metal in the aqueous phase by inorganic ligands and plausible complexes extracted into the organic phase. The results demonstrate that Zn(II) is extracted as Zn(SCN)₂·2B2EHSO and Zn(SCN)₂·2TBP. In the case of Cd(II), the extracted species are Cd(SCN)₂·4B2EHSO/4TBP. The synergistic extraction of Zn(II) and Cd(II) with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and B2EHSO or TBP or trioctylphosphine oxide (TOPO) from acetate buffer solutions has also been investigated. Zn(II) is extracted as Zn(PMBP)₂·B2EHSO/TBP/TOPO. On the other hand, Cd(II) is found to be not extracted with these mixed-ligand systems under the experimental conditions. These results also demonstrate the mutual separation of Zn(II) and Cd(II) using the synergistic extraction with HPMBP in the presence of various neutral oxodonors.     

Synergistic extraction of uranium(VI) and americium(III) with binary mixtures of Aliquat 336 and PC 88A-TOPO from nitric-sulfuric acid medium

Synergism is observed in the extraction of uranium(VI) by the binary mixture of Aliquat 336 and PC 88A (2-ethylhexylphosphonic acid mono-2-ethylhexyl ester) from 0.5–6M HNO₃ solution showing a maximum at 3M. In H₂SO₄ medium, antagonism at lower acidity and slight synergism at higher acid concentrations have been observed. Synergism occurs in the extraction of Am(III) from nitrate solutions when a mixture of Aliquat 336 and TOPO is used.     

PMTFP与中性磷萃取剂对钇(Ⅲ)的协同萃取

本文用萃取法测定了(Ⅰ)Y(Ⅲ)/0.5MNaClO_4/PMTFP—C_6H_6和(Ⅱ)Y(Ⅲ)/0.5MNaClO_4/PMTFP—TBP—C_6H_6及(Ⅲ)Y(Ⅲ)/0.5MNaClO_4/PMTFP—TOPO—C_6H_6体系的萃取平衡常数和协苹平衡常数,结果如下: 体系(Ⅰ)的1gK3_(30)=-3.36;体系(Ⅱ)的1gK_(32)=4.47; 体系(Ⅲ)的1gK_(31)=6.65、1gK_(32)=9.08。     

Solvent extraction of metal ions with mixed ligands: Extraction and separation of calcium and strontium with TTA and TBP in carbon tetrachloride

The solvent extraction of calcium(II) and strontium(II) by TTA has been studied using carbon tcetrachloride containing trioctylphosphine oxide (TOPO), tributylphosphate (TBP), and methyl isobutyl ketone (hexone) as adduct-forming ligands. Stability constants for the systems are given. The separation of calcium and strontium can be effected by 0.1 M TTA +0.01 M TBP in carbon tetrachloride.     

Solvent extraction of zirconium from hydrochloric acid solutions by sulphoxides and their mixtures

The solvent extraction of zirconium from HCl solutions by dipentyl sulphoxide (DPSO), dioctyl sulphoxide (DOSO), tributyl phosphate (TBP), and their mixtures in various solvents has been studied. At a given H⁺ strength, the extraction coefficient η of the metal increases with an increase in Cl⁻ activity whereas it is almost independent of H⁺ at constant Cl⁻. Under otherwise identical conditions, η increases with an increase in the extractant concentration but is virtually independent of the metal ion concentration over a wide range. The species extracted are ZrCl₄·DPSO, ZrCl₄·DOSO, and ZrCl₄·2TBP. In the case of mixtures, the slope of the log η−log M extractant plot for one component decreases with an increase in the concentration of the second component, the lines crossing at a common point. Extraction is favoured by solvents of low dielectric constant. It is possible to separate zirconium from thorium and uranium by solvent extraction with sulphoxides.     

Extraction of Am(III) by mixture of dihexyl N,N-diethylcarbamoylmethyl phosphonate and tributyl phosphate in benzene from nitric acid solutions

Extraction of Am(III) by dihexyl N,N-diethylcarbamoylmethyl phosphonate (CMP) in benzene from nitric acid solutions (pH 2.0 to 6.0M) has been studied. High extraction of Am(III) by CMP from 2–3M HNO₃ was observed. The species extracted was found to be Am(NO₃)₃·3CMP. The extraction was also done with mixtures of CMP+TBP and CMP+TOPO, where mixed species were extracted in the organic phase. The back-extraction experiments gave an efficient back-extraction of Am(III) by pH 2.0 (HNO₃) from the loaded CMP+TBP phase but a poor back-extraction from the loaded CMP+TOPO phase. The loading of Nd(III) by mixture of CMP and TBP was 50% of the CMP concentrations at a total Nd(III) concentration of 0.182M. The thermodynamic parameters of Am(III) extraction by a mixture of CMP and TBP were evaluated by temperature variation method, which suggests that the two-phase reaction is stabilized by enthalpy and opposed by entropy.     

Synergistic extraction of uranyl thenoyltrifluoroacetonate with trioctyl phosphine oxide

Synergistic effect with a strong donor, trioctyl phosphine oxide (TOPO), has been studied in the extraction of thenoyltrifluoroacetone (TTA) complexes of uranyl ion. The chemical form of the species extracted was found to be the 1∶1 adduct, UO₂A₂·S (S∶TOPO), and no evidence was found concerning other mixed complexes. Adduct formation constants determined in twelve inert solvents vary from lg K_S=6.79 in chloroform to 9.58 in n-hexane, while their increasing order is almost the same as that for the adducts with other phosphine oxides and TBP.     

Synergistic extraction of uranium(VI) and thorium(IV) with mixtures of Cyanex272 and other organophosphorus ligands

The extraction of thorium(IV) and uranium(VI) from nitric acid solutions has been studied using mixtures of bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex272 or HA), and synergistic extractants (S) such as tri-butylphosphate (TBP), tri-octylphosphine oxide (TOPO) or bis(2,4,4-trimethylpentyl)thiophosphinic acid (Cyanex301). The results showed that these metallic ions are extracted into kerosene as Th(OH)₂(NO₃)A·HA and UO₂(NO₃)A·HA with Cyanex272 alone. In the presence of neutral organophosphorus ligands TBP and TOPO, they are found to be extracted as Th(OH)₂(NO₃)A·HA·S and UO₂(NO₃)A·HA·S. On the other hand, Th(IV), U(VI) are extracted as Th(OH)₂(NO₃)A·HA·2S and UO₂(NO₃)A·HA·S in the presence of Cyanex301. The addition of neutral extractants such as TOPO and TBP to the extraction system enhanced the extraction efficiency of both elements while Cyanex301 as an acidic extractant has improved the selectivity between uranium and thorium. The effect of TOPO on the extraction was higher than other extractants. The equilibrium constants of above species have been estimated by non-linear regression method. The extraction amounts were determined and the results were compared with those of TBP. Also, it was found that the binding to the neutral ligands by the thorium–Cyanex272 complexes follows the neutral ligand basicity sequence.     

Thermodynamics of the extraction of Eu3+ with thenoyltrifluoroacetone,triphenylarsine oxide and other phosphine oxides

Extraction of Eu³⁺ from 0.1M aqueous perchlorate medium by thenoyltrifluoroacetone (HTTA) and by mixtures of HTTA and tributylphosphate (TBP), HTTA and triphenylphosphine oxide (TPPO), HTTA and trioctylphosphine oxide (TOPO) and HTTA and triphenylarsine oxide (TPAsO) has been studied at various temperatures allowing for the elucidation of the mechanism of extraction in each case and a comparison between the various bases.     

Effect of interaction of thenoyltrifluoroacetone with neutral oxo-donors in the synergistic extraction of tervalent actinides

The interaction of HTTA with TBP, DOSO, DBBP and TOPO in xylene has been studied by a spectrophotometric method. The complex species formed is HTTA. S (where S is a neutral donor) and the equilibrium constants for the formation of the species follow the order TOPO > DBBP > DOSO > TBP. After application of a correction for the HTTA-S interaction, the free HTTA and S concentrations in the organic phase were calculated. Plots of log D vs. log [HTTA] for the tervalent actinides Am, Cm, Bk and Cf gave straight lines with a slope of 3 only after application of the interaction correction, otherwise curves with slopes varying from 3 to 2 were found. The equilibrium constants of the organic phase synergistic reactions of the tervalent actinides are found to be approximately 10% higher after application of the HTTA-S interaction correction.     

Synergism in the extraction of cerium using nitrogen-base donors

Synergism in the extraction of cerium in presence of a mixture of a β-diketone and nitrogen donors like pyridine, 2,4-dimethylpyridine, quinoline and 8-nitroquinoline has been investigated. The nature of the extracted species has been investigated and the equilibrium constants for adduct formation have been calculated. Synergism increased in the order 8-nitroquinoline < pyridine ≈ quinoline > 2,4-dimethyl pyridine.     

Synergistic effect of tri-<Emphasis Type="Italic">n</Emphasis>-butyl phosphate (TBP) or tri-<Emphasis Type="Italic">n</Emphasis>-octyl phosphine oxide (TOPO) with didodecylphosphoric acid (HDDPA) on extraction of uranium(VI) and thorium(IV) ions

Importance of removal of radioactive elements from wastewater was the motivation behind this work. Synergistic solvent extraction of U(VI) and Th(IV) ions from perchlorate solution using didodecylphosphoric acid (HDDPA) incorporated with tri-n-butyl phosphate (TBP) or tri-n-octylphosphine oxide (TOPO) as a synergists have been studied for the first time. The effects of HDDPA concentration, synergist’s concentration, pH values and temperature on the extraction process have been studied. The thermodynamic parameters of the extraction process for these ions were calculated. It was found that the synergistic contribution of TOPO is higher than TBP in the extraction of Th(IV) and U(VI).     

Extraction of zirconium(IV) from hydrochloric acid solutions by tri-octylamine and neutral donors

Solvent extraction of Zr(IV) from aqueous HCl solutions by mixtures of TOA and different organophosphorous bases in carbontetrachloride solvent have been found to be always higher than that by any single extractant. Synergism has been observed in the range of 2.4–9.6M HCl. Although the species extracted with neutral donor alone seems to be ZrCl₄·TOPO etc, with a mixture of extractants, however, the extracted species appears to be Q₂ZrCl₆·TOPO where Q is R₃NH. The extraction has also been found to increase with increase in the concentration of amines and neutral donors. Enhancement of extraction has been explained by the formation of a complex adduct in organic phase. Synergistic coefficients and apparent formation constants of the complex adducts have also been calculated.     

Determination of plutonium by solvent extraction—Liquid scintillation method

A combined solvent extraction—liquid scintillation method is suggested for the determination of plutonium. The quenching by twenty four extracting reagents was examined systematically, and the organo phosphorus extractants such as tributylphosphate (TBP), bis-(2-ethyhexyl) phosphoric acid (HDEHP), and tri-n-octylphosphineoxide (TOPO) were shown to be least quenching compared with amines and beta-diketones. Using TOPO, plutonium from 1 ng to 2 μg was determined within 5% of standard deviation, and the detection limit was 3·10⁻¹⁰ g of²³⁹Pu. The quenching by the different ions and the effects of the radioactive elements were also shown.