Studies on synergistic extraction of thorium by mixtures of HTTA and TBP

Synergistic extraction of Th(IV) from perchlorate medium by mixtures of HTTA and TBP was studied. These studies include the effect of the ionic strength, temperature and the diluents on the extraction. Ionic strength was found to influence the extraction of Th(TTA)₄ and Th(TTA)₄·TBP whereas the adduct formation in the organic phase was almost unaffected. Increase of temperature resulted in a decrease of the extraction of Th(IV). The stability of the adduct was found to decrease in the order, cyclohexane > benzene > chloroform.     

Some studies on synergic extraction of mixed ligand species of uranium(VI)

The extraction of U(VI) by mixtures of HTTA and TBP from aqueous thiocyanate medium has been studied. From the data obtained it was observed that the predominant uranium species extracted, causing synergic enhancement in the extraction of U(VI), is UO₂(SCN)TTA · 2TBP when benzene and cyclohexane are used as diluents, and that at a very low concentration of TBP the contribution of additional species, viz. UO₂(TTA)₂ · TBP becomes significant. With chloroform as diluent, however, both of these species are contributing to the synergic enhancement. The extraction of a quaternary uranium species, UO₂(SCN)TTA · 2TBP, involving the participation of the aqueous anion is thus established. Equilibrium constants for the various extraction equilibria involved are calculated.     

Dependence of primary and secondary emulsion formation on the concentration of TBP,HNO3 and additives

Model studies on TBP—diluent—aqueous HNO₃ extraction systems were performed to establish the mechanism of emulsyfying during the reprocessing of spent reactor fuel with mixtures of TBP solutions. The systems of interest were emulsified under fixed conditions. The rate of separation of the primary emulsion as well as the turbidity of each phase were determined. The experiments were performed on mixtures of pure components of the extraction systems. Emulsion stability was investigated in terms of the influence of such factors as main products of TBP decay, the type of diluents, HNO₃ concentration and concentration of TBP in different diluents.     

Determination of trace elements in wool fibre by instrumental neutron activation analysis and relation between trace element contents and quality of wool

Synergistic extraction of uranyl ion with 2-thenoyltrifluoroacetone (HTTA) and aliphatic amides with varying basicities, viz. dibutyl hexanamide (DBHA), dibutyloctanamide (DBOA) or dibutyldecanamide (DBDA) has been studied at various fixed temperatures of 20, 30, 40 and 50±0.1°C. Results indicate that the equilibrium constants of the organic phase addition reaction (Ks) with these amides follow their order of basicity (Kh) viz. DBHA (0.09)<0.10) H DBOA (0.13) with log Ks values of 4.91, 4.99 and 5.02, respectively. These values are much higher than those with TBP (3.8) or sulfoxides (4) as donors. This may be attributed to the existence of a resonance form of the amide, which has higher electron density on the carbonyl oxygen. The thermodynamic parameters associated with these systems evaluated by the temperature coefficient method indicate that the organic phase addition reaction with all the three amides is stabilized by both enthalpy and entropy changes as against UO ₂ ²⁺ /HTTA/TBP system, where only the enthalpy change contributes to the stabilization.     

Influence of diluent on the synergic extraction of divalent cobalt by the thenoyltrifluoroacetone-tribenzylamine perchlorate system

The effect of ten pure diluents and different mixtures of nitrobenzene and toluene on the synergic extraction of Co²⁺ by the thenoyltrifluoroacetone (HTTA)-tribenzylamine (TBA) mixture is studied. The logarithm of the extraction constant of Co(TTA)₂ increases with increasing dielectric constant of the diluent, whereas the logarithm of the formation constant of the extracted adduct Co(TTA)₂TBA decreases with increasing dielectric constant of the diluent. This behaviour is explained by changes in the hydrophobic character of the extracted species. The theory of regular solutions is successfully applied to the extracted adduct. Consideration of the self-association of the amine salt is necessary in the treatment of the equilibria involved.     

Synergistic extraction of trivalent Am,Cm, Bk and Cf with HTTA+TBP in xylene

The synergistic extraction of trivalent actinides Am, Cm, Bk and Cf with thenoyltrifluoro acetone (HTTA) and tributyl phosphate (TBP) has been studied in xylene at 30°C. Correction for the HTTA-TBP interaction has been applied to get the free TBP concentration in the organic phase. Plots of log D vs. log [HTTA] give straight lines with a slope of 3 only after correcting for the HTTA-TBP interaction; without this correction the slope varies from 3 to 1 with increasing HTTA concentrations. The presence of two synergistic species M(TTA)₃·TBP and M(TTA)₃·2TBP simultaneously has been observed. The equilibrium constants for the organic phase synergistic reactions have been calculated.     

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.     

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.     

Temperature effect on the synergic extraction of europium by thenoyltrifluoroacetone in the presence of heterocyclic bidentate amines from acetate buffer solutions

Temperature effect on the synergic extraction of Eu(III) by thenoyltrifluoroacetone (HTTA) in the presence of 2,2-bipyridyl(bipyr) and 1,10-phenanthroline (phen) from sodium acetate buffer solution at pH 4.20 has been investigated. Extractions were carried out at 15, 25, and 35°C. It was observed that the increasing temperature favours the extraction of Eu(III) by HTTA alone while the reverse is true for synergic extractions. The extraction data indicate the formation of synergic adducts containing only one molecule of the bidentate amine i.e. Eu(TTA)₃. B where B=bipyr or phen. The synergic reaction is favoured by the enthalpy changes alone. Thermodynamic parameters suggest a mechanism for the synergic extraction which involves complex formation with an increase or expansion of the coordination number of the central metal atom. Larger synergic and enthalpy changes observed for phen as compared to bipyr are probably due to the cis position of its N-atoms readily available for chelate ring formation.     

Calorimetric studies on the thermal decomposition of tri n-butyl phosphate-nitric acid systems

Thermal decomposition of neat TBP, acid-solvates (TBP·1.1HNO₃, TBP·2.4HNO₃) (prepared by equilibrating neat TBP with 8 and 15.6?M nitric acid) with and without the presence of additives such as uranyl nitrate, sodium nitrate and sodium nitrite, mixtures of neat TBP and nitric acid of different acidities, 1.1?M TBP solutions in diluents such as n-dodecane (n-DD), n-octane and isooctane has been studied using an adiabatic calorimeter. Enthalpy change and the activation energy for the decomposition reaction derived from the calorimetric data wherever possible are reported in this article. Neat TBP was found to be stable up to 255?°C, whereas the acid-solvates TBP·1.1HNO₃ and TBP·2.4HNO₃ decomposed at 120 and 111?°C, respectively, with a decomposition enthalpy of ?495.8?±?10.9 and ?1115.5?±?8.2?kJ?mol^?1 of TBP. Activation energy and pre exponential factor derived from the calorimetric data for the decomposition of these acid-solvates were found be 108.8?±?3.7, 103.5?±?1.4?kJ?mol^?1 of TBP and 6.1?×?10¹⁰ and 5.6?×?10⁹?S^?1, respectively. The thermochemical parameters such as, the onset temperature, enthalpy of decomposition, activation energy and the pre-exponential factor were found to strongly depend on acid-solvate stoichiometry. Heat capacity (C _p ), of neat TBP and the acid-solvates (TBP·1.1HNO₃ and TBP·2.4HNO₃) were measured at constant pressure using heat flux type differential scanning calorimeter (DSC) in the temperature range 32?C67?°C. The values obtained at 32?°C for neat TBP, acid-solvates TBP·1.1HNO₃ and TBP·2.4HNO₃ are 1.8, 1.76 and 1.63?J?g^?1?K^?1, respectively. C _p of neat TBP, 1.82?J?g^?1?K^?1, was also measured at 27?°C using ??hot disk?? method and was found to agree well with the values obtained by DSC method.     

Synergic extraction of thorium by beta-isopropyltropolone-neutral donor combinations

The extraction of thorium by benzene solutions of HIPT in presence of different neutral extractants (S) was studied using perchloric, hydrochloric and sulphuric acids as aqueous media. With TBP as the donor the effect of the diluents CCl₄, benzene and CHCl₃ on the extraction was studied. The synergism observed was attributed to the formation of the extractable adduct Th(IPT)₄ · S and, in some cases, to the extraction of additional mixed adducts involving the participation of the anion of the aqueous medium used for extraction. The adduct formation constants for the formation of Th(IPT)₄ ·S were evaluated and the formation of this adduct was independently confirmed by spectrophotometric measurements. The aqueous complexing of thorium by IPT was investigated spectrophotometrically as these data were required for the quantitative interpretation of the extraction data.     

Solvent extraction of Np(IV) and Pu(IV) with mixtures of TOPO and HTTA

Solutions of HTTA are known to extract tetravalent actinides as M(TTA)₄ species. When TOPO is added to HTTA solutions, the extracting of Np(IV) and Pu(IV) from aqueous perchloric acid was enhanced enormously. The species responsible for the enhanced extraction were identified from the extraction data by the slope ratio method and JOB's method. It was found that the predominant species responsible for enhancement in the extraction, when [HTTA]≫[TOPO], was M(TTA)₄. TOPO for both Np(IV) and Pu(IV). Furthermore, it was established that depending on the relative concentrations of HTTA and TOPO, a number of species with the composition M(TTA)_a(ClO₄)_4-a·b TOPO, with a ranging from 1 to 4 and b having values of 1 or 2, are involved in the extraction. Several equilibrium constant values are given. Fuel Reprocessing Division.     

Studies on extraction of thorium(IV) from sulfate media with mixtures of long-chain primary amines and tributyl phosphate

The partition of Th(IV) from H₂SO₄ solutions with extractant mixtures of long-chain primary amine (Primene JMT, PrJT) and tributyl phosphate (TBP) is described. Exraction was optimized at PrJT/TBP molar ratio of about 3. The dependence of extraction on acidity, salting agent, extractant concentration, diluent type and temperature, was investigated. From the results obtained, the extracted species are suggested and enthalpy data determined.     

不同稀释剂中TBP萃取醋酸的研究

研究了不同稀释剂中ＴＢＰ对醋酸的萃取，其萃取能力在不同稀释剂中按甲苯〉苯〉环己烷〉煤油〉四氯化碳〉氯仿〉甲基异丁基酮的顺序变化，求出了萃取反应的焓变，建立了萃取平衡常数与稀释剂物理参数间的经验方程，并用红外光谱对萃取机理进行了研究。     

Synergistic extraction of hexavalent actinides by HTTA and neutral donors-II

Synergistic extraction studies on Np(VI) and Pu(VI) have been carried out as a part of the programme on the synergistic extraction of hexavalent actinides. Extraction of Np(VI) and Pu(VI) were carried out by mixtures of HTTA and TBP in benzene from aqueous perchlorate and nitrate media. Equilibrium constant values for the various reaction equilibria involved were calculated from the data obtained by using slope-ratio as well as Job’s method. The extraction of Np(VI) by the synergistic mixture from 1M nitric acid indicated that the species NpO₂ (TTA) (NO₃). TBP was not involved in the extraction. The log values of K_A, K_AB and β_AB were −1.5, 2.92 and 4.43, respectively for Np(VI) and −1.63, 2.50 and 4.13 respectively for Pu(VI).     

Solvent extraction of uranyl by N,N,N′,N′-tetraoctylsuccinylamide from nitric acid solution

Synthesis and characterization of N,N,N′,N′-tetraoctylsuccinylamide (TOSA) was carried out and used for extraction of U(VI) from nitric acid solutions. The effect of different factors affecting the extraction distribution ratio (TOSA concentration, concentrations of nitric acid, salting-out agent LiNO₃ concentration, equilibration time, temperature and effect of diluents) have been investigated. The results obtained indicated that TOSA have a great capability to extract uranyl with kerosene-1,3,5-trimethylbenzene than other diluents, it have a high extraction distribution ratios when the concentration of TOSA is lower and not found the third matter. It was found that the main extracted species is UO₂(NO₃)₂·TOSA. The apparent equilibrium constant of extraction determined is (2.32 ± 0.31) L³/mol³ at (298 ± 1) K. The enthalpy of extraction is ?35.20 ± 0.352 kJ/mol.     

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.     

Liquid-liquid extraction of thorium/IV/ with LIX-54 and its mixtures

Solvent extraction of thorium/IV/ by a commercially available chelating extractant LIX-54 /a -diketone derivative/ /HA/ and its mixtures with tri-n-butyl phosphate /TBP/, thenoyltrifluoroacetone /HTTA/ and tri-n-octyl phosphineoxide /TOPO/ in benzene as the diluent have been studied. Quantitative extraction of thorium/IV/ by the mixture of 10% LIX-54 and 0.1M TOPO was noticed at pH 2.8. Influence of various concentrations of HTTA and TOPO in their mixtures with LIX-54 on the extraction of the same metal ion has been investigated and pronounced synergism was observed. Slope analyses determination shows the extracted species to be possibly of the type [Th/TTA/₂/A/₂] in case of extraction by mixtures of HTTA and LIX-54. Slopes of the linear plots were computed employing regression analysis, and variance in results has been shown.     

Extraction of Nitric Acid and Np(IV) by some aliphatic ketones and alcohols

The extraction behaviour of HNO₃ and Np(IV) from aqueous nitrate solutions with some aliphatic alcohols and ketones using hexane, carbon tetrachloride, benzene and chloroform as diluents was studied. The acid concentration in the aqueous phase varied from 0.25 to 10 M and that of the extractant in the organic phase varied from 0.5 M to the undiluted fraction. In the alcohol systems, solutions of the same alcohol in the diluents CCl₄ and CHCl₃ showed similar capacity for acid extraction, and also in the same diluents, solutions of diisopropyl and diisobutyl alcohol showed similar capacity for extraction. Extraction of Np(IV) with the different ketones and alcohols used follow the same pattern as HNO₃.     

Synergistic extraction of uranium(VI) with tri-n-butyl phosphate and i-butyldodecylsulfoxide

Summary The synergistic extraction of uranium(VI) from aqueous nitric acid solution with a mixture of tri-n-butyl phosphate (TBP) and i-butyldodecylsulfoxide (BDSO) in toluene was investigated. The effects of the concentrations of extractant, nitric acid, sodium nitrate and sodium oxalate on the distribution ratios of uranium(VI) have been studied. The values of enthalpy change for the extraction reactions with BDSO, TBP and a mixture of TBP and BDSO in toluene were -23.2±0.8 kJ/mol, -29.2±1.4 kJ/mol and -30.6±0.6 kJ/mol, respectively. It has been found that the maximum synergistic extraction effect occurs when the molar ratio of TBP to BDSO is close to 1. The composition of the complex of the synergistic extraction is UO₂(NO₃)₂ ^. BDSO ^. TBP.