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.     

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.     

Synergic extraction of divalent iron,cobalt, copper and zinc with thenoyltrifluoroacetone-dibenzylamine in chloroform

The solvent extraction of divalent iron, cobalt, copper and zinc from perchlorate medium of constant ionic strength (0.1 H⁺, NaClO₄) into a mixture of thenoyltrifluoroacetone (HTTA) and dibenzylamine (DBA) in chloroform has been studied. The extraction of the different cations were found to increase by more than 10³ order of magnitude in presence of DBA. Slope analysis of the extraction results assumed a general formula of M(TTA)₂·DBA for the extractable adduct. A stability order of Fe(TTA)₂·DBA>Co(TTA)₂ ·DBA>Zn(TTA)₂·DBA>Cu(TTA)₂·DBA has been decumented.     

Thermodynamics of solvent extraction of thorium by solutions of HHTA and mixtures of HHTA and TBP

The changes in free energy, enthalpy and entropy for the extraction of thorium by solutions of thenoyltrifluoroacetone (HTTA) and mixtures of solutions of HTTA and tri-n-butylphosphate (TBP), in three diluents, viz. cyclohexane, benzene and chloroform, were determined using the solvent extraction data obtained at different temperatures. From these data the thermodynamic parameters associated with the formation of Th(TTA)₄ · TBP in the respective organic diluents were evaluated. Trends in the enthalpy changes were attributed to different degrees of association of the diluents with themselves and with the solutes present in them.     

Lanthanoid complexes with thenoyltrifluoroacetone and 4-tert-butylcalix[4]arene-tetraacetic acid tetraethyl ester: synergistic extraction and separation

The solvent extraction of fourteen lanthanoid ions with thenoyltrifluoroacetone (HTTA) in combination with tetraethyl 4-tert-butylcalix[4]arene-tetraacetic acid tetraethyl ester (S) from a perchlorate medium at constant ionic strength was investigated. The extracted species were identified as the Ln(TTA)₃·S complexes by slope analysis. Equilibrium constants, parameters for extraction, and the synergistic and separation factors between two adjacent Ln(III) ions were determined.

Solvent extraction of Tm(III) by sulfoxides and mixtures of DPSO (di-N-pentyl sulfoxide) and HTTA (thenoyl-trifluoroacetone) from perchlorate and thiocyanate media

Extraction of Tm(III), from thiocyanate media, by different sulfoxides (R₂SO) has revealed that the extractable complex is Tm(SCN)₃·4 R₂SO. When mixtures of DPSO and HTTA are used for the extraction of Tm(III) from thiocyanate or perchlorate media, synergistic enhancement of the extraction of Tm(III) results. The complexes responsible for the enhanced extraction are Tm(TTA)₃·DPSO and Tm(TTA)₃·2 DPSO when perchlorate media were employed for the extraction and Tm(SCN)(TTA)₂·2 DPSO and Tm(SCN)₂(TTA)·3 DPSO, in addition to the above two when a thiocyanate medium was employed for the extraction. Values of equilibrium constants for some equilibria encountered in the extraction of Am(III) and Tm(III) by mixtures of DPSO and HTTA are given.     

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.     

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).     

轻希土与2－噻吩甲酰三氟丙酮和1, 10－二氮杂菲配合物的合成及荧光光谱

本文采用溶剂萃取法和乙醇-水溶液析出法合成了六种轻希土与2-噻吩甲酰三氟丙酮(HTTA)和1,10-二氮杂菲(phen)三元配合物.通过元素分析、红外光谱、热重及荧光光谱等测试手段,考察了配合物有关性质,并确定了其组成为RE(TTA)₃phen和RE(TTA)₃phen·H₂O(RE=La、Ce、Pr、Nd、Sm、Eu).     

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.     

Synergetic extraction of Co3+

The extraction of Co³⁺ from 0.1M aqueous acetate medium buffered to pH 5.3 by thenoyltrifluoroacetone (HTTA) in benzene and by 8-quinolinol (HQ) also in benzene at various temperatures has been studied. The species formed were Co(OH)₂ (TTA)·(HTTA)₂ and Co(Q₃)·2HQ, respectively. 1,10-phenanthroline (Phen) as a base was also mixed with HTTA to form the species Co(OH)₂(TTA)·(HTTA). Phen and Co(OH)₂ (TTA)(HTTA)·2Phen. No synergism was observed upon the addition of Phen to HQ.     

Structure and dynamics of binary and ternary lanthanide(III) and actinide(III) tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione] (TTA)-tributylphosphate (TBP) complexes. Part 3, the structure, thermodynamics and reaction mechanisms of 8- and 9-coordinated binary and ternary Y-TTA-TBP complexes studied by quantum chemical methods

Possible mechanisms for intermolecular exchange between coordinated and solvent water in the complexes Y(TTA)(3)(OH(2))(2) and Y(TTA)(3)(TBP)(OH(2)) and intermolecular exchange between free and coordinated HTTA in Y(TTA)(3)(OH(2))(HTTA) and Y(TTA)(3)(TBP)(HTTA) have been investigated using ab initio quantum chemical methods. The calculations comprise both structures and energies of isomers, intermediates and transition states. Based on these data and experimental NMR data (Part 2) we have suggested intimate reaction mechanisms for water exchange, intramolecular exchange between structure isomers and intermolecular exchange between free HTTA and coordinated TTA. A large number of isomers are possible for the complexes investigated, but only some of them have been investigated, in all of them the most stable geometry is a more or less distorted square anti-prism or bicapped trigonal prism; the energy differences between the various isomers are in general small, less than 10 kJ mol(-1). 9-coordinated intermediates play an important role in all reactions. Y(TTA)(3)(OH(2))(3) has three non-equivalent water ligands that can participate in ligand exchange reactions. The fastest of these exchanging sites has a QM activation energy of 18.1 kJ mol(-1), in good agreement with the experimental activation enthalpy of 19.6 kJ mol(-1). The mechanism for the intramolecular exchange between structure isomers in Y(TTA)(3)(OH(2))(2) involves the opening of a TTA-ring as the rate determining step as suggested by the good agreement between the QM activation energy and the experimental activation enthalpy 47.8 and 58.3 J mol(-1), respectively. The mechanism for the intermolecular exchange between free and coordinated HTTA in Y(TTA)(3)(HTTA) and Y(TTA)(3)(TBP)(HTTA) involves the opening of the intramolecular hydrogen bond in coordinated HTTA followed by proton transfer to coordinated TTA. This mechanism is supported by the good agreement between experimental activation enthalpies (within parenthesis) and calculated activation energies 68.7 (71.8) and 35.3 (38.8) kJ mol(-1). The main reason for the difference between the two systems is the much lower energy required to open the intramolecular hydrogen bond in the latter. The accuracy of the QM methods and chemical models used is discussed.     

Synergic extraction of trivalent iron and cobalt with thenoyltriflouroacetone and certain benzylamines in chloroform

Synergic extraction of trivalent iron and cobalt with thenoyltriflouroacetone (HTTA) and the synergic bases (B) benzylamine (BA), dibenzylamine (DBA) and tribenzylamine (TBA) was studied. The extracted adducts proved to have the general formula M(TTA)₃·B for all the amines investigated. The formation constants of the mixed-ligand complexes decrease in the order DBA>TBA>BA. While equilibrium constant β_3,1 for the Co(TTA)₃·DBA complex is higher than the corresponding iron adduct, β_3,1 for the iron adducts with BA and TBA are higher than those for cobalt.     

Synergistic extraction of tetravalent actinides by mixtures of a β-diketone and a sulfoxide

Synergistic extraction of tetravalent actinides, using mixtures of a β-diketone and several neutral organophosphorous extractants, was recently demonstrated. In this work the extraction of the ions Th(IV), Np(IV) and Pu(IV), from perchloric acid medium, by benzene solutions of a β-diketone, thenoyltrifluoroacetone (HTTA), in combination with a neutral organosulfoxide donor, di-n-octyl sulfoxide (DOSO), has been investigated. Two methods viz. the slope analysis method and JOB's method have been employed for the study. The species mainly responsible for the observed synergism, with the M(IV) ions studied, was found to be M(TTA)₄·DOSO. The extraction and adduct formation equilibrium constants are given.     

A Comparative Study of the Solvent Extraction of the Trivalent Elements of the Lanthanoid Series with Thenoyltrifluoroacetone and 4-Benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one Using Diphenylsulphoxide as Synergistic Agent

Solvent extraction of the trivalent lanthanoids (except Pm) with mixtures of a chelating extractant, either 1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedione (thenoyltrifluoro-acetone, HTTA) or 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP) and diphenylsulphoxide (S), from chloride solutions has been studied in C₆H₆. It was found that, in the presence of a diphenylsulfoxide, the lanthanoids were extracted as Ln(TTA)₃⋅S and LnP₃⋅S. The extraction data have been analyzed by a graphical method taking into account aqueous phase speciation and the plausible complex extracted into the organic phase. On the basis of the experimental data, values of the equilibrium constants have been calculated. Positive values of the synergistic coefficients show that all lanthanoids are extracted synergistically upon the addition of compound S to the chelating extractant. The separation of the lanthanoids with synergistic mixtures was, in most cases, a little higher than those obtained using HTTA or HP alone.     

Interaction effect between thenoyltrifluoroacetone and tri-n-octylphoshine oxide in the synergistic extraction of trivalent lanthanides. Determination of the composition of the extracted species+ of the extracted species

The distribution constant K_D(HTTA) of thenoyltrifluoroacetone between 10^–3M HNO₃ and cyclohexane was determined by means of spectrophotometric measurements of HTTA concentration in the aqueous phase. The distribution ratio, D, of HTTA, when tri-n-octylphosphine (TOPO) is present, and the equilibrium constant, _n , of the reaction between HTTA and TOPO in the organic phase were also determined. By means of the known K_D(HTTA) and D values, the equilibrium constant of the HTTA-TOPO interaction was calculated. Making use of K_D(HTTA) and _n values and of the slope analysis method, the composition of the extracted lanthanide complexes was established. By considering the interaction reaction between the extractants, the species Ln(TTA)₃ · TOPO and Ln(TTA)₃ · 2(TOPO), for Ln=La and Yb, were identified in the organic phase. The equilibrium constants of the reactions that give rise to the species were also calculated.From a thesis submitted by D. I. T. FÁVARO to the University of São Paulo in partial fulfillment for a Doctor of Sciences Degree in Nuclear Technology.     

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.     

2,2′-Dipyridyl and 1,10-phenanthroline in the synergetic extraction of Eu3+

The thermodynamics of the extraction of Eu³⁺ by thenoyltrifluoroacetone (HTTA) and by mixtures of HTTA and bidentate amine bases such as 2,2-dipyridyl (Dipy) and 1,10-phenanthroline (Phen) in benzene from an aqueous phase fixed to 0.1M ionic strength (NaClO₄), pH 3.9, has been investigated. Phenanthroline forms both the Eu(TTA)₃·Phen and Eu(TTA)₃·2Phen species, which are much stronger than the dipyridyl complexes. The diluent effect on the extraction is also studied.     

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.     

Structure and dynamics of binary and ternary lanthanide(III) and actinide(III) tris[4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione] (TTA) complexes. Part 2, the structure and dynamics of binary and ternary complexes in the Y(III)/Eu(III)-TTA-tributylphosphate (TBP) system in chloroform as studied by NMR spectroscopy

The stoichiometric reaction mechanisms, rate constants and activation parameters for inter- and intramolecular ligand exchange reactions in the binary Y/Eu(TTA)(3)(OH(2))(2)-HTTA and the ternary Y/Eu(TTA)(3)(OH(2))(2)-TBP systems have been studied in chloroform using (1)H and (31)P NMR methods. Most complexes contain coordinated water that is in very fast exchange with water in the chloroform solvent. The exchange reactions involving TTA/HTTA and TBP are also fast, but can be studied at lower temperature. The rate constant and activation parameters for the intramolecular exchange between two structure isomers in Y(TTA)(3)(OH(2))(2) and Y(TTA)(3)(TBP)(OH(2)) were determined from the line-broadening of the methine protons in coordinated TTA. The rate equations for the intermolecular exchange between coordinated TTA and free HTTA in both complexes are consistent with a two-step mechanism where the first step is a fast complex formation of HTTA, followed by a rate determining step involving proton transfer from coordinated HTTA to TTA. The rate constants for both the inter- and intramolecular exchange reactions are significantly smaller in the TBP system. The same is true for the activation parameters in the Y(TTA)(3)(OH(2))(2)-HTTA and the ternary Y/Eu(TTA)(3)(TBP)(OH(2))-HTTA systems, which are ΔH(≠) = 71.8 ± 2.8 kJ mol(-1), ΔS(≠) = 62.4 ± 10.3 J mol(-1) K(-1) and ΔH(≠) = 38.8 ± 0.6 kJ mol(-1), ΔS(≠) = -93.0 ± 3.3 J mol(-1) K(-1), respectively. The large difference in the activation parameters does not seem to be related to a difference in mechanism as judged by the rate equation; this point will be discussed in a following communication. The rate and mechanism for the exchange between free and coordinated TBP follows a two-step mechanism, involving the formation of Y(TTA)(3)(TBP)(2).