Search Results

You are looking at 1 - 10 of 38 items for :

  • "Europium(III)" x
  • All content x
Clear All

Abstract  

The sorption of small amounts of europium(III) on iron(III) hydroxide and oxide has been studied as a function of pH. The mechanism of sorption is discussed. Optimum conditions have been found for the preconcentration of small or trace amounts of europium(III) by iron(III) hydroxide and oxide. The influence of complexing agents (EDTA, oxalate, tartrate and 5-sulfosalicylic acid) on the sorption of small amounts of europium(III) on iron(III) oxide has also been studied.

Restricted access

Abstract  

Eu-151 Mössbauer spectra of tetrakis/diethyldithiophosphato/europium/III/ compounds suggests substantial electron transfer from dithiophosphate ligand to europium. The photochemical reaction of these complexes was investigated in organic solutions, and it was demonstrated that the Mössbauer isomer shift was correlated with their 420 nm band.

Restricted access

Abstract  

The151Eu Mössbauer spectra were measured of surface-oxidized europium/II/ sulfate with the γ-ray transmission- and conversion electron technique. The comparison of such spectra demonstrated that the change in the oxidation state of trace amounts of europium induced by surface reactions could be characterized by the conversion electron Mössbauer technique. The photochemical reduction of europium/III/ oxalate to a Eu/II/species after irradiation with a low-pressure mercury lamp was demonstrated by means of this technique as well as ESR.

Restricted access

Summary  

The extractive properties of 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(diphenylphosphinoylmethoxy)calix[4]arene towards thorium(IV) and europium(III) ions are studied. The conventional log-log analysis of the extraction data reveals that the stoichiometry of the extracted species is 1 : 1 metal ion to ligand ratio for the two metals. The effects of ligand concentration, types of diluent and concentration of the salting-out agents are investigated and discussed. The selectivity of the ligand for thorium and europium ions versus Mn2+, Pb2+, Cd2+, Fe2+, Ni2+ and Co2+ is examined.

Restricted access

Abstract  

The extraction of plutonium(IV), uranium(VI), zirconium(IV), europium(III) and ruthenium(III) with -pre-irradiated n-dodecane solutions of methylbutyl substituted hexanamide (MBHA), octanamide (MBOA) and decanamide (MBDA) from 3.5M HNO3 has been studied as a function of absorbed dose up to 184×104 Gray. The distribution ratios (Kd) of uranium(VI) decreased gradually up to a dose of 50×104 Gray and became almost constant thereafter, while ruthenium(III) and europium(III) were not extracted in the entire dose range studied. The Kd values of Pu(IV) decreased gradually up to 10×104 Gray, for MBOA, and 30×104 Gray for MBHA and MBDA and then increased up to a dose of 72×104 Gray, indicating the synergistic effect of radiolytic products at higher doses. The extraction of zirconium(IV) was found to increase gradually up to 72×104 Gray. However, the steep fall in Kd values of plutonium(IV), zirconium(IV) beyond a dose of 72×104 Gray was atrributed to third phase formation. The radiolytic degradation of amides was monitored by quantitative IR spectroscopy and was found to follow the order MBOA>MBDA>MBHA at 184×104 Gray having the amines and carboxylic acids as the main radiolytic products.

Restricted access

Abstract  

Solvent extraction of65zinc,60cobalt and152+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 Kex, where Kex 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).

Restricted access

Abstract  

A new chelating polymeric sorbent has been developed using polystyrene resin grafted with phosphonic acid. After characterization by FTIR and elementary analysis, the new resin has been investigated in liquid–solid extraction of europium(III). The results indicated that phosphonic resin could adsorb Eu(III) ion effectively from aqueous solution. The adsorption was strongly dependent on pH of the medium with enhanced adsorption as the pH value of 6.5. The influence of other analytical parameters including contact time, amount of resin, metal ion concentration, and ionic strength were investigated. The maximum uptake capacity of Eu(III) ions was 122.6 mg/g grafted resin at ambient temperature, at an initial pH value of 6.50. The overall adsorption process was best described by pseudo first-order kinetic. When Freundlich and Langmuir isotherms were tested, the latter had a better fit with the experimental data. Furthermore, Eu(III) could be eluted by using 1.0 mol/L H2SO4 solution and the grafted resin could be regenerated and reused.

Restricted access

Summary  

Sorption behavior of europium, Eu3+, on SiO2 . xH2O (silica gel) has been investigated as a function of time, the amount of silica gel, Eu3+ concentration, the ionic strength, and pH (in absence and in presence of carbonate). The sorption data were fitted to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. The sorption capacity of silica gel was determined to be in the range of (2.62-8.00) . 10-7 mol/g at pH 5.30±0.05 and 0.20M NaClO4. The mean energy of sorption was calculated to be 13.50±0.05 kJ/mol from the D-R isotherm, suggesting the involvement of ion-exchange reactions in the sorption process. Sorption of Eu3+ decreased with increased ionic strength. A gradual decrease in pH with increased ionic strength supports the involvement of an ion-exchange mechanism in the sorption process. The diffusion coefficient of Eu3+ ion on silica gel was calculated as (3.98±0.12) . 10-13 m2 . s-1 under the particle diffusion-controlled conditions.

Restricted access

Abstract  

The interaction of the clinically used 1,2-dimethyl-3-hydroxypyrid-4-one with trivalent europium Eu(III), was investigated by using potentiometric and spectroscopic methods. The stability constants of the EuLn (3−n)+ complexes determined by spectroscopic and potentiometric measurements were found to be log β11 = 6.5±0.3 and log β12 = 12.0±0.5. However, at pH ≥ 5, hydrolysis of the Eu-L complexes starts, resulting in the formation of needle-type, yellow crystals. The low solubility of the Eu-L complexes in the neutral pH range is disadvantageous with respect to the use of deferiprone as chelating agent for decorporation of trivalent f-elements.

Restricted access

Summary  

The sorption of Eu(III) ions onto PAN loaded PUF has been optimized and investigated under the influence of various temperatures, i.e., 303, 313 and 323 K. Maximum retention (>96%) of Eu(III) ions (1.79. 10-5M) onto PAN loaded PUF (7.75 mg. ml-1) was achieved after 30-minute equilibration time from pH 7 buffer solution. The variation of sorption with temperature yields the thermodynamic parameters ΔH=79±2 kJ. mol-1, ΔS=276±7 kJ. mol-1. K-1and ΔG=-1.4±0.1 kJ. mol-1at 298 K. The positive value of enthalpy and negative free energy show endothermic and spontaneous nature of sorption, respectively. The sorption data followed Freundlich, Dubinin-Radushkevich (D-R) and Langmuir isotherms at all the three given temperatures. The Freundlich constant 1/n=0.70, 0.62 and 0.55 and sorption capacities C m=10.8 mmol. g-1, 6.1 mmol. g-1and 4.4 mmol. g-1, respectively, decreased with increasing temperature. Similarly, the sorption capacities of D-R isotherm X m=197.6 µmol. g-1, 201.2 µmol. g-1and 137.4 µmol. g-1, also decreased with temperature. However, the sorption free energy E=10.2 kJ. mol-1, 11.2 kJ. mol-1and 12.7 kJ. mol-1, increased with temperature. The monolayer coverage (Q) computed from Langmuir isotherm was 11.1±0.6 µmol. g-1and remains constant at all the three temperatures investigated. However, the binding energy constant bincreased with temperature. The relationship of bwith temperature and differential heat of adsorption (ΔH diff) have been evaluated and discussed.

Restricted access