The synergistic extraction of thorium(IV) and uranium(VI) with mixtures of 3-phenyl-4-benzoyl-5-isoxazolone and crown ethers

The extraction of thorium(IV) and uranium(VI) from nitric acid solutions has been studied using mixtures of 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) and dicyclohexano-18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6 or benzo-15-crown-5. The results demonstrate that these metal ions are extracted into chloroform as Th(PBI)(4) and UO(2)(PBI)(2) with HPBI alone and as Th(PBI)(4) . CE and UO(2)(PBI)(2) . CE in the presence of crown ethers (CE). The equilibrium constants of the above species have been deduced by non-linear regression analysis. The addition of a CE to the metal chelate system enhances the extraction efficiency and also improves the selectivities between thorium and uranium. IR spectral data of the extracted complexes were used to further clarify the nature of the complexes. The binding to the CEs by Th(PBI)(4) and UO(2)(PBI)(2) follows the CE basicity sequence but with DC18C6 and DB18C6, steric effects become more important.     

Complexation of trivalent lanthanoid ions with 4-benzoyl-3-phenyl-5-isoxazolone and p-tert-butylcalix[4]arene fitted with phosphinoyl pendant arms in solution during synergistic solvent extraction and structural study of solid complexes by IR and NMR

The liquid extraction of 14 lanthanoids with a 4-benzoyl-3-phenyl-5-isoxazolone (HPBI) alone in CHCl₃ as a diluent from perchlorate medium at constant ionic strength μ = 0.1 is investigated. The synergistic solvent extraction of five selected lanthanoid ions (La³⁺, Nd³⁺, Eu³⁺, Ho³⁺ and Lu³⁺) with 4-benzoyl-3-phenyl-5-isoxazolone (HPBI) and 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis-(dimethylphosphinoylmethoxy)calix[4]arene, (S) in CHCl₃ has been studied too. The stoichiometry of the extracted species was characterised by a classical log–log plot analysis. It was found that the composition of the extracted species with HPBI are Ln(PBI)₃ and in the presence of the phosphorus-containing calix[4]arene the lanthanoid ions have been extracted as [Ln(PBI)₃S₂]. The values of the equilibrium constants and the separation factors have been calculated. The influence of the synergistic agent on the extraction process has been discussed.     

Extraction of thorium(IV) by a mixture of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and tri-n-octyl phosphine oxide

The extraction behavior of Th(IV) from dilute nitric as well as perchloric acid medium using 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) and its mixture with tri-n-octyl phosphine oxide (TOPO) was investigated. The species of the type Th(X)(PMBP)₃·(HPMBP) and Th(X)(PMBP)₃·(TOPO) were extracted for the binary and ternary extraction systems, respectively, where X=NO₃− or ClO₄−. The presence of 1.25·10⁻⁵M Th carrier in the aqueous phase resulted in the extracted species of the type of Th(PMBP)₄ and Th(PMBP)₄·(TOPO), respectively. The extraction constant (logk _ex ) for the binary species Th(PMBP)₄ was found to be 6.89±0.01 while the overall extraction constant (logK) for the ternary species Th(PMBP)₄·(TOPO) was calculated to be 13.17±0.06.     

Solvent extraction behaviour of lanthanum(III), cerium(III), europium(III), thorium(IV) and uranium(VI) with 3-phenyl-4-benzoyl-5-isoxazolone

The extraction behaviour of La(III), Ce(III), Eu(III), Th(IV) and U(VI) with 3-phenyl-4- benzoyl-5-isoxazolone (HPBI) in chloroform has been studied. The mechanism of extraction and the species extracted have been identified. Extraction constants for each system have been calculated. The system has been used to separate Th(IV) from U(VI) and from La(III), Ce(III) and Eu(III). A comparison of the extraction constants with those for the 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) and thenoyltrifluoroacetone (HTTA) systems indicates that HPBI extracts these metal species better than HPMBP and HTTA do.     

Synergistic extraction of alkaline earth cations with 3-phenyl-4-benzoyl-isoxazol-5-one and tri-n-octylphosphine oxide in toluene

The synergistic extraction of alkaline earth cations from 1M NaNO₃ aqueous solutions with 3-phenyl-4-benzoylisoxazol-5-one (HPBI) and tri-n-octylphosphine oxide (TOPO) in toluene at 25°C has been studied. The extraction efficiency follows the order Ba²⁺<Sr²⁺<Ca²⁺<Mg²⁺, which is the same as that previously observed with 1-phenyl-3-methyl-4-benzoyl-pyrazol-5-one (HPMBP). The extraction occurs at a lower pH range than with HPMBP because of the higher acidity of HPBI. The extracted species are M(PBI)₂(TOPO) _x withx=2 for M=Mg, Ca, Sr and Ba (logK _1,2,2=3.91, 1.18 and 0.29 respectively) and withx=3 for M=Sr and Ba (logK _1,2,3=3.28 and 2.07 respectively). The strong interactions which occur between HPBI and TOPO (logK _int=1.84) have been considered in the extraction constant calculations..     

Synergistic extraction of cobalt (II) by beta hydroxy naphthaldoxime and neutral donors

Liquid - liquid extraction of Cobalt (II) from aqueous hydrochloric acid medium by the use of oxime derivative of beta-hydroxy naphthaldehyde in o-xylene medium is being reported. The ligand was synthesized and characterized in our laboratory. The typical pH range of extraction of Co (II) by the ligand - donor combination was seen to be between 8 - 9. The effect of different donors like dimethyl sulphoxide (DMSO), trioctyl phosphine oxide (TOPO) and bis(2-ethylhexyl) phosphonate and the effect of various diluents on the extraction of Co(II) by the present method were studied in detail. The binary adduct formation constant (log kex) in the organic phase was found to be 3.182. The overall equilibrium constant (log K) for the ternary species [Co(A)(DMSO)(Cl)], [Co(A)(TOPO)(Cl)] and [Co(A)(phosphonate)(Cl)] were estimated to be 6.42, 6.22 and 6.25 respectively. The trend in equilibrium constants were in accordance with their basic character, i.e., (DMSO > or = TOPO approximately/= phosphonate). The results were extrapolated in the determination of Cobalt in pharmaceutical drugs and cobalt bearing ore samples.     

Studies on the liquid-liquid extraction of iron(III) and titanium(IV) with 3-phenyl-4-benzoyl-5-isoxazolone

The extraction behaviour of iron(III) and titanium(IV) from acidic chloride solutions has been investigated using 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) in xylene as an extractant. The results demonstrate that these metal ions are extracted into xylene as Fe(PBI)(3) and TiO(PBI)(2). The equilibrium constants of the extracted complexes have been deduced by non-linear regression analysis by taking into account complexation of metal ion with inorganic ligands in the aqueous phase and all plausible complexes extracted into the organic phase. IR and proton NMR ((1)H NMR) spectra were used to further clarify the nature of complexes extracted into organic phase. The effect of the nature of the diluent on the extraction of iron(III) and titanium(IV) has been studied and correlated with dielectric constants. The extraction behaviour of titanium(IV) has also been compared with that of other metal ions, viz. magnesium(II), vanadium(V), chromium(VI), iron(III), manganese(II), zinc(II) and zirconium(IV), which are associated with the titanium in waste chloride liquors of the titanium-mineral-processing industry.     

3-Phenyl-4-benzoyl-5-isoxazolone: A promising chelate extractant for actinide separation from acidic nuclear waste solutions

In the presence of tri-n-octyl-phosphine (TOPO) oxide, 3-phenyl-4-benzoyl-5-isoxazolone (PBI) has been found to be a promising chelate extractant for the partitioning of actinides from acidic nuclear waste solutions. Quantitative extraction of Pu and U is possible in the nitric acid concentration range 1–6 M, whereas Am can be extracted only from solutions with an acidity . Extraction studies of Am and U under varying loading conditions are also carried out and conditions for quantitative stripping are arrived at.     

Role of solvents in the synergistic extraction of metal complexes

The extraction equilibria of Co(II) and Zn(II) complexes with 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one in the presence of tributyl phosphate have been investigated in eight ‘inert’ solvents employing the radioisotopes cobalt-60 and zinc-65. The activity coefficients of different species in the organic phase and the solubility parameter of the adduct have been calculated with the help of regular solution theory. A regularity is observed in the correlation between the adduct formation constant and the activity coefficient of the species.     

Steric effect of ortho-substituents of 1-phenyl-3-methyl-4-aroyl-5-pyrazolones on the synergic extraction of lutetium with trioctylphosphine oxide

The substituent effect of ortho-substituted 4-aroyl derivatives of 1-phenyl-3-methyl-5-pyrazolones (HA) on the adduct formation reaction between their lutetium chelates and a neutral ligand, trioctylphosphine oxide (TOPO, L), in benzene was studied using a liquid-liquid extraction system. The lutetium 4-aroyl-5-pyrazolonates react with TOPO to form LuA₃L and LuA₃L₂ types of adducts. An obvious steric hindrance of the terminal group on the adduct formation reaction was observed. Linear relationships between the acid dissociation constant of the ortho-substituted 4-aroyl-5-pyrazolone derivatives and those of the corresponding benzoic acids, between the extraction constants of lutetium and the acid dissociation constants of pyrazolones and between the adduct formation constants of TOPO and the acid dissociation constants of pyrazolones could be obtained.     

Synergistic extraction of U(VI) and Th(IV) from nitric acid with 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (HBMPPT) and tri-n-octylphosphine oxide (TOPO) in toluene

The extractant HBMPPT (4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione) was synthesized from HBMPP. Its m.p. was 106–108°C. The synergistic extraction of U(VI) and Th(IV) from nitric acid solution by HBMPPT and TOPO in toluene was studied. The extraction ability of HBMPPT was not so high as that of its parent (HBMPP), but when a little tri-n-octylphosphine oxide (TOPO) was added the ability to extract U(VI) and Th(IV) was seriously improved. The synergistic extracted complexes may be presented as UO₂NO₃·BMPPT·TOPO and UO₂(BMPPT)₂·TOPO for U(VI), and Th(NO₃)₃·BMPPT·TOPO and Th(NO₃)₂(BMPPT)₂·TOPO for Th(IV) respectively.     

溶剂萃取动力学的研究 II: 三辛基氧化膦从盐酸体系中萃取铀(IV)的速率

The kinetics of the oxtraction of U(IV) chloride in the TOPO-HCl system has been studied using the single drop technique, The effects of the concentrations of U(IV, TOPO and HCl on the extraction rate for U(IV) have been examined. The extraction rate measured were found to be of first order with respect to (U(IV)) and (TOPO) (0). Moreover, the rate varied with (HCl)^3^/^2 between 2-7M hydrochloric acid. The extraction rate equation can be written as R=K(U(IV))(TOPO)(0) The rate constant K was evaluated to be 3.7X10^-^5 at 3M HCl and 15`C. The extraction rate was increased with increasing temperature. The apparent activation energy was found to be 10.8 kcal/mol between 15 to 45`C. It is suggested that the rate-controlling step may be the chemical reaction of UCl4 with TOPO at the interface and the formation of the interfacial complex UCL4.TOPO.     

3-Phenyl-4-benzoyl-5-isoxazolonate complex of Eu3+ with tri-n-octylphosphine oxide as a promising light-conversion molecular device

Three new europium complexes, [Eu(PBI)3.3H2O] (1), [Eu(PBI)3.2TOPO] (2), and [Eu(PBI)3.2TPPO.H2O] (3) (where HPBI, TOPO, and TPPO stand for 3-phenyl-4-benzoyl-5-isoxazolone, tri-n-octylphosphine oxide, and triphenylphosphine oxide, respectively), with different neutral ligands were synthesized and characterized by elemental analysis, Fourier transform infrared, (1)H NMR, thermogravimetric analysis, and photoluminescence (PL) spectroscopy. The coordination geometries of the complexes were calculated using the Sparkle/AM1 (Sparkle Model for the Calculation of Lanthanide Complexes within the Austin Model 1) model. The ligand-Eu3+ energy-transfer rates were calculated in terms of a model of the intramolecular energy-transfer process in lanthanide coordination compounds reported in the literature. The room-temperature PL spectra of the europium(III) complexes are composed of the typical Eu3+ red emission, assigned to transitions between the first excited state (5D0) and the multiplet (7F(0-4)). On the basis of emission spectra and lifetimes of the 5D0-emitting level, the emission quantum efficiency (eta) was determined. The results clearly show that the substitution of water molecules by TOPO leads to greatly enhanced quantum efficiency (i.e., 26% vs 92%) and longer 5D0 lifetimes (250 vs 1160 micros). This can be ascribed to a more efficient ligand-to-metal energy transfer and a less nonradiative 5D0 relaxation process. Judd-Ofelt intensity parameters (Omega2 and Omega4) were determined from the emission spectra for the Eu3+ ion based on the 5D0 --> 7F2 and 5D0 --> 7F4 electronic transitions, respectively, and the 5D0 --> 7F1 magnetic-dipole-allowed transition was taken as the reference. A point to be noted in these results is the relatively high value of the Omega2 intensity parameter for all of the complexes. This may be interpreted as being a consequence of the hypersensitive behavior of the 5D0 --> 7F2 transition. The dynamic coupling mechanism is, therefore, dominant, indicating that the Eu3+ ion is in a highly polarizable chemical environment.     

Adduct formation properties of mono- and bidentate phosphine oxide compounds in the liquid—liquid extraction of some divalent metals with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone

The bidentate phosphine oxide compounds bis(diphenylphosphinyl)methane (BDPPM) and bis(diphenylphosphinyl)ethane (BDPPE) were synthesized and the liquid—liquid extraction equilibria of some divalent metal ions such as Co(II), Ni(II), Zn(II) and Cd(II) with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) and the neutral phosphine oxide compounds were investigated. BDPPM was found to be much more powerful than BDPPE and the monodentate neutral ligand trioctylphosphine oxide (TOPO). The composition of the extracted species were determined by a graphical method to be M(PMBP)₂(TOPO)_s (s = 2 for Co, Ni, Cd and s = 1 for Zn), M(PMBP)₂(BDPPM) and M(PMBP)₂(BDPPE). The adduct formation constants between the acylpyrazolone chelates and the neutral ligands were determined and are discussed in terms of the molecular structure.     

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.     

Synergism in the extraction of europium in the presence of alkylphosphates and sulphoxides

Synergism in the extraction of europium(III) has been investigated using a mixture of naphthoyltrifluoroacetone and synergists like trioctylphosphine-oxide (TOPO), tributylphosphate (TBP), trihexylphosphate (THP), diphenylsulphoxide (DPSO) and benzylsulphoxide (BSO). Synergism decreases in the order: TOPO < TBP ≃THP < BSO < DPSO indicating a correlation between electron density at the donor atom and extent of synergism. The equilibrium constants for adduct formation have also been evaluated.     

Uranium dioxide in ionic liquid with a tri-n-butylphosphate-HNO3 complex--dissolution and coordination environment

Uranium dioxide can be dissolved directly in an imidazolium-based ionic liquid (IL) at room temperature with a tri-n-butylphosphate(TBP)-HNO(3) complex. The dissolution process follows pseudo first-order kinetics initially. Raman spectroscopic studies show the dissolved uranyl ions are coordinated with TBP in the IL phase with a molar ratio of (UO(2))(2+) : TBP = 1 : 2. The dissolved uranyl species can be effectively transferred to a supercritical fluid carbon dioxide (sc-CO(2)) phase. No aqueous phase is formed in either the IL dissolution or the supercritical fluid extraction process. Absorption spectra of the extracted uranyl species in the sc-CO(2) phase suggests the presence of a UO(2)(TBP)(2)(NO(3))(2) and HNO(3) adduct probably of the form UO(2)(TBP)(2)(NO(3))(2)·HNO(3). The adduct dissociates in a water-dodecane trap solution during pressure reduction resulting in UO(2)(TBP)(2)(NO(3))(2) collected in the dodecane phase.     

Synergistic extraction of uranium(VI) with 1-phenyl-3-methyl-4-acylpyrazolone-5 and neutral extractants

The synergistic extraction of uranium(VI) from hydrochloric acid solution with five chelating agents: 1-phenyl-3-methyl-4-benzoylpyrazolone-5 (PMBP), 1-phenyl-3-methyl-4-acetylpyrazolone-5 (PMAP), 1-phenyl-3-methyl-4-(2-chlorobenzoyl)pyrazolone-5 (PMCBP), 1-phenyl-3-methyl-4-(p-nitrobenzoyl)pyrazolone-5 (PMNBP) and 1-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5 (PMTFP) plus the neutral extractants tributylphosphate (TBP), dioctyl sulfoxide (DOSO) and trioctylphosphine oxide (TOPO) in chloroform has been investigated. The extraction coefficients have been found to be greater for such mixtures than the individual component. The formulas of the extracted species have been determined to be UO₂A₂B (where HA = chelating agent, B = neutral extractant). Extraction power of these chelating agents increases as follows: PMCBP>PMNBP>PMTFP=PMBP>PMAP. Synergistic extraction power of the neutral extractants increases as follows: TOPO>DOSO>TBP. The extraction equilibrium constants have been calculated. The mechanism of the synergistic extraction and possible structure of the extracted species are discussed.     

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.     

Synergistic effect of HBMPPT with PSO, DOSO and TBP on the extraction of U(VI) and on the separation of U(VI) and Th(IV)

Some popular neutral extractants (PSO-petroleum sulfoxide, DOSO-di-n-octyl sulfoxide, TBP-tributylphosphate etc.) were chosen as synergist to study the synergistic effect on the extraction reaction with HBMPPT (4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione) for U(VI), and the synergistic separation ability of HBMPPT for U(VI) and Th(IV). The synergistic extraction ability shown by the studied systems for U(VI) is as follows: PSO>DOSO>TBP, and the same sequence was also verified for the separation coefficient of U(VI) and Th(IV). The synergistic complexes may be presented as: UO₂NO₃·BMPPT·S and UO₂(BMPPT)₂·S for U(VI) (S is PSO, DOSO or TBP).