Extraction of europium from nitrate solutions in the presence of polyfunctional organic compounds

The extraction of europium with benzene solutions of tributyl phosphate (TBP), benzoic acid (BA), and acetylacetone (AA) from nitrate solutions has been studied in the presence of the following polyfunctional organic compounds: acrylamide (AAm), phenanthroline (Phen), Diacetam-5, and Tinuvin-622. Europium distribution data in combination with luminescence spectroscopy of extracts are used to discuss europium complexing with the specified ligands. A feasibility of manufacturing Eu₂O₃ and EuPO₄ films on quartz through the pyrolysis of saturated extracts is demonstrated.     

Yttrium complexation with benzoic acid and tris(hydroxymethyl)aminomethane

Yttrium complexation in extraction systems with benzoic acid (BA) and tris(hydroxymethyl)aminomethane (THMAM) was studied. The growth of yttrium distribution ratios in this system is caused by the formation of different-ligand coordination compounds of yttrium with BA and THMAM. Quantum chemical calculations for the formation energy of different-ligand complex showed that the most stable complex forms when yttrium atom coordinates to two THMAM molecules via oxygen and nitrogen atoms and to one THMAM molecule via nitrogen atom. The complex is stable in both bidentate and monodentate coordination of the carboxyl groups of benzoic acid to yttrium atom. Obtained yttrium extracts were used for the synthesis of complex-oxide nanosized cathodophosphors by extraction-pyrolytic technique.     

Terbium extraction in the presence of polyfunctional organic compounds and the composition of the extract pyrolysis products

Terbium extraction with benzene solutions of acetylacetone, bipyridine, and diphenylguanidine and their mixtures from aqueous chloride solutions, in particular, in the presence of tris(hydroxymethyl)aminomethane was studied. On the basis of terbium distribution in extraction systems in combination with IR and luminescence spectroscopy data for the extracts, the complexation of terbium with these ligands was discussed. The composition of the products of the pyrolysis of extracts was studied. It was shown that pyrolysis of saturated extracts can give nano-sized bulk samples and films on a quartz substrate for both terbium oxide and terbium and manganese mixed oxides.     

Extraction of europium complexes with 1,2,4,5-benzenetetracarboxylic acid and neutral ligands

Extraction of mixed-ligand europium complexes with 1,2,4,5-benzenetetracarboxylic (pyromellitic) acid and neutral ligands was studied. The complexation of europium with the ligands is discussed on the basis of data on europium distribution in extraction systems, as well as IR and luminescent spectroscopy data of extracts. Crystalline polynuclear europium complexes with pyromellitic acid and 1,10-phenanthroline and tris(hydroxymethyl)aminomethane were isolated from the extracts. The composition of pyrolysis products of extracts was studied. It was shown that nanosized bulk samples of europium oxide can be obtained by the pyrolysis of saturated extracts. Differences in the morphology of europium oxide nanoparticles were revealed in the samples obtained by pyrolysis of extracts differing in composition at the same temperature and time.     

Effect of gamma-radiation on the extraction of europium and americium by benzyldibutylamine

The effect of gamma irradiation on benzene solutions of benzyldibutylamine with cetyl alcohol used for the extraction of europium and americium from nitrate solutions was investigated. The dependence of the distribution coefficient on the dose absorbed either by the whole system or some efficient component was measured. Nitric acid present during irradiation significantly lowers the radiation stability, while benzyldibutylamine and cetyl alcohol appear to be radiostable components. Up to tens of kGy's—the doses expected in an extraction process from highly active solutions—the system seems to be quite stable.     

Interference of elements upon extraction by macrocyclic extractants

The extraction of cations of a series of alkali and alkali-earth metals, along with Pb(II), Rh(III), and Pd(II) with crown, thiacrown and azacrown ethers from picric and nitric acid solutions was studied. Upon the extraction of metal cations with macrocyclic extractants, the interference of those cations on the extraction of one another was observed in polar solvents. The causes of this phenomenon are revealed, and a mechanism for the suppression of extraction of the microcomponent with the macrocomponent is proposed. Upon the simultaneous extraction of americium (III) and europium (III) with calixarenes the co-extraction was noted for the first time, resulting in the good extraction of Am(III) from nitric acid solutions. We hypothesize on the formation of a mixed nitrate complex of americium and europium that can be effectively extracted into an organic phase with calixarenes.     

Effect of tris(hydroxymethyl) aminomethane on the phase behavior of poly(ethylene imine)/cinnamic acid conjugate and the release property of cubic phase containing the conjugate

The upper critical solution temperature (UCST) of poly(ethylene imine)/cinnamic acid (PEI/CA) conjugate decreased as the tris(hydroxymethyl) aminomethane (THMAM) concentration increased. On the optical micrographs of PEI/CA mixture solutions at 25°C, the microspheres were found when the THMAM concentration was 0?mM and 100?mM, but hardly found at 200?mM. Monoolein (MO) cubic phase containing PEI, CA, and THMAM exhibited a bilayer structure on the TEM micrograph. The release degree of methylene blue loaded in the cubic phase was not strongly dependent on THMAM concentration at 25°C and 37°C, but strongly dependent on the concentration at 50°C.     

Kinetics of americium and europium extraction by tert-butylthiacalix[4]arene from alkaline media

Kinetics of ¹⁵²Eu and ²⁴¹Am extraction by nitrogen-bearing alkyl amino phenol oligomer YaRB and tert-butylthiacalix[4]arene TCA from carbonate-alkaline media was studied. Both extractants efficiently extract americium and europium in pH interval 12–14. The maximum of americium extraction is located at the lower values of pH, compared with europium. YaRB extracts americium and europium faster than TCA, and at the same time, americium is extracted faster than europium by both extractants. In general, thiacalixarene TCA is regarded as more efficient extractant than alkyl amino phenol oligomer YaRB.

     

Studying the sorption properties of a clinoptilolite-containing tuff with respect to europium(III) ions

The kinetic laws of sorption of europium(III) ions from sulfate solutions by a clinoptilolite-containing tuff are studied. The kinetic parameters of sorption process are determined and absorption isotherms are constructed for europium ions. It is found that both external and internal diffusion are rate-limiting steps, and europium is completely extracted from dilute solutions (<0.0025 m).     

Mixed ligand complexes of europium,dialkylphosphoric acids and perchlorate anion

The solvent extraction of europium(III) with di-n-butylphosphoric {HDBP} and di-(2-ethylhexyl)phosphoric {HDEHP} acids in 3-methyl-1-butanol from 0.1 and 1.0M perchlorate medium {Na(H)ClO₄} was studied at pH 1–3. It was found that the composition of the species extracted into the organic phase depended on the concentration of perchlorate anion. In 0.1M Na(H)ClO₄ solutions, simple chelates Eu(DBP)₃ or Eu(DEHP)₃ are extracted while mixed ligand complexes Eu(DBP)₂ClO₄ or Eu(DEHP)₂ClO₄ are also extracted from 1.0M Na(H)ClO₄ solutions. Compared to the extractions from perchlorate solutions, no such change in the extraction mechanism has been observed in chloride solutions containing up to 1.0M Cl^–. The extraction of europium(III) with these extractants into toluene from 0.1M perchlorate or chloride media was studied as well. The extraction species found were identical with those reported in the literature, i.e. {Eu[H(DBP)₂]₃, Eu[H(DEHP)₂]₃}. The extraction equilibrium constants were calculated for all complexes.     

Kinetics of zinc(II) cloride extraction with tributyl phosphate

The equilibrium and rate of solvent extraction of zinc chloride complexes from HCl solutions into benzene solutions of tributyl phosphate (TBP) have been studied. The extracted species are discussed in the light of the results. The extraction was found to be first order with respect to both Zn(II) and TBP, and zero order for HCl. The rate-controlling steps are discussed and the rate constants for these reactions are calculated.     

Steric aspects of selectivity of organophosphorus extractants

This paper is devoted to the steric aspects of the efficiency and selectivity of extractants in the process of extraction of metal cations from acidic aqueous solution into a nonpolar phase. The extraction of uranium, plutonium, americium, and europium by tertiary carbamoylmethyl phosphine oxides and polydiphenylphosphinylmethyl benzenes have been studied. The separation factors of uranium and plutonium from americium are measured. Tertiary carbamoylmethyl phosphine oxides and diphenylphosphinylmethyl benzenes of the ortho type are characterized by unusually high separation factors. The diphenylphosphinylmethyl derivatives of benzene of the meta type do not possess a high selectivity in the process of separation of uranium and plutonium from americium, but are more efficient in extraction of americium.     

Extraction chromatographic material with HDEHP on polyacrylonitrile (PAN)

Four composite materials with di-(2-ethylhexyl) phosphoric acid (HDEHP) as an extraction agent and PAN as a binding polymer were studied in this work. The intended use of these materials is in extraction chromatography. They were prepared by various methods and contained different amounts of HDEHP. The properties were compared by studying europium uptake from nitric acid solutions. Materials prepared by direct incorporation of extraction agent into PAN polymer during beads production and with up to 40% (w/w) of HDEHP are suitable for analytical separations. Materials with high capacity can be prepared by impregnation of ready-made PAN beads.     

The use of trioctylphosphine oxide for solvent extraction recovery and purification of transplutonium elements

Extraction of trivalent curium, berkelium, californium, einsteinium, and europium with trioctylphosphine oxide (TOPO) from nitric acid solutions as well as extraction of curium and cerium from lactic acid solutions containing DTPA depending on aluminium nitrate concentration have been studied. The distribution of cobalt, nickel, chromium, iron, aluminium, titanium, zirconium, and niobium ions has been studied and coefficients of berkelium purification from the elements studied have been determined under the conditions of extraction-chromatographic recovery of berkelium. The influence of weighed amounts of the same impurities on the yield of berkelium in its extraction-chromatographic separation has been studied. Some examples of the practical application of the extraction-chromatographic techniques using TOPO are given.     

Sorption of a complex of europium (III) with acetylacetone on hydrophobized hexadecyl silica gel and hyper crosslinked polysterene

The sorption of a complex of europium (III) with acetylacetone on silica gel chemically modified with hexadecyl groups (SiO₂-C₁₆) and hyper crosslinked polystyrene (HLPS) was studied. Maximum extraction was observed at pH 5–7 when SiO₂-C₁₆ was used as the sorbent and at pH 4–7 in the case of crosslinked polystyrene. The partition coefficients for HLPS and silica gel were calculated as 7 × 10³ and 1 × 10² cm³/g, respectively. Quantitative extraction of the europium (III) complex was possible in dynamic conditions using a microcolumn (length, 10 mm; internal diameter, 3mm) packed with HLPS at pH 5 (10–50 mL sample volume). Desorption of europium using solutions of nitric acid at different concentrations was investigated. Quantitative desorption was achieved using 5 mL of 1 M HNO₃. A linear range of detection was observed at an amount of europium from 5 to 25 μg in a 10-mL sample (650 nm).     

Thermodynamics of the solvent extraction of thorium and europium nitrates by neutral phosphorylated ligands

Solvent extraction of tetravalent thorium and trivalent europium ions from nitrate media into dichloromethane solution of triphenylphosphine oxide (TPPO) has been studied. The extractant was shown to be more efficient for europium than for thorium. A conventional log-log analysis reveals that the extraction of both metal nitrates takes place via the formation of the species with 1 : 2 metal to ligand ratio. Thermodynamic parameters i.e., ΔG°, ΔH° and ΔS° of the extraction process using 1,2-dichloroethane as diluent have been calculated based on the influence of the temperature on extraction equilibria in the range 293-313 K. While the extraction of europium is controlled by enthalpy changes, the extraction of thorium is an endothermic process and is driven by entropy changes. A comparison of these data with those obtained for the extraction of europium and thorium nitrates by two other related phosphorylated ligands, tri-n-octylphosphine oxide (TOPO) and diphenyl-N,N-dimethylcarbamoylmethylphosphine oxide (DФDMCMPO), indicates that DФDMCMPO coordinates presumably as a chelating ligand. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solvation of thiocyanate complexes of mercury(II) by 2-hexylpyridine from aqueous mineral acid solutions

The extraction of trace amounts of mercury(II) by 2-hexylpyridine dissolved in benzene from aqueous mineral acid solutions has been studied. The replacement of chloride, nitrate and sulfate ions by the potentially ambidentate, linear and less basic thiocyanate group offers interestingly high extraction coefficients. The value of the distribution coefficients may be lowered by complexing mercury with oxalate, thiosulfate, acetate or citrate ions in the aqueous phase. The possible mechanism of extraction has been discussed in the light of the results of extraction isotherms and slope analysis data. Distribution coefficients and separation factors of several metal ions relative to mercury(II) are reported for the three mineral acid systems and the possible removal of mercury along with some other inorganic pollutants from aqueous solutions is suggested.     

Extraction chromatography of common anions in liquid-liquid anion exchange systems. Part. III. Monobasic aliphatic organic acids and their sodium salts as eluants

Summary The chromatographic behaviour of anions on paper strips treated with tri-n-octylamine (TOA) salts or Aliquat 336 and developed with aqueous solutions of acetic, formic, monochloroacetic or trifluoroacetic acids and their sodium salts was investigated. Liquid-liquid extraction of organic acids by 0.1 M solution of TOA in benzene as well as the anion exchange between benzene solutions of TOA salts or Aliquat 336 (in acetate form) in benzene and aqueous solutions of sodium halides was also studied. It was found that extraction increases in the following order of the acids: CH₃COOOH<HCOOH<CH₂CICOOH<CF₃COOH; the relative affinity of organic anions to the quaternary alkyl-ammonium cation also increase in a similar order. The extraction of acid in excess over the amount necessary to neutralize the amine was observed for all four acids. The R_F values of anions investigated depend markedly on the type of organic acids or their salts and their concentration in the mobile phase. Halide ions are more strongly retained on paper treated with Aliquat 336 as compared with TOA salts. The chromatographic systems investigated offer many possibilities to separate various anion mixtures.Parts and II: refs. [1, 2].     

Interference of elements upon extraction by oxygen-containing extractants: Calculating the distribution coefficients

The extraction of tellurium (IV), tin (IV), and indium (III) by aliphatic alcohols and ketones from hydrochloric acid solutions was studied both upon the individual separation of elements and upon their simultaneous extraction. Electroconductivities of the extracts were measured and, using these data, the dissociation constants of the extracted metal-halogen acids in organic solvents were calculated by Fuoss-Krauss method. A method for calculating the distribution coefficients of elements upon their simultaneous extraction by hydrate-solvate and mixed solvate and hydrate-solvate mechanisms is proposed. It is shown that the calculated distribution coefficients are in good agreement with the experimental data.     

Solvent extraction of cobalt(II), zinc(II) and europium(III) with 4-thiobenzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one (SBMPP)

Solvent extraction of⁶⁵zinc,⁶⁰cobalt and^152+154europium from aqueous buffers into benzene containing 4-thiobenzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one (SBMPP) has been investigated in detail (μ=0.1, T=26±1°C). The species extracted and the values of log K_ex, where K_ex refers to the extraction equilibrium, are ZnL₂ (−2.68) CoL₂(−3.08) and EuL₃(−7.08), where L is the anion of the ligand. The sulfur analog appears to be more effective than the parent ligand 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one in the extraction of zinc(II) and cobalt(II), whereas the reverse is true with europium(III).