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  • Author or Editor: S. Khalifa x
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Abstract  

The effect of adding 15-crown-5 (15C5) or 18-crown-6 (18C6)CE, for the extraction of Eu(III) or Gd(III)M3+, by thenoyltrifluoroacetone (HTTA) in benzene from a nitrate aqueous medium of constant ionic strength [0.2(H+, NaNO3)] was studied. The results indicated that the extraction is enhanced by adduct formation in the organic phase, the main extracted species formed being M(NO3)(TTA)2HTTA for the chelate and M(NO3)(TTA)2·CE for the adduct. The extraction and stability constants of these species were evaluated. The thermodynamic parameters for the extraction of both Eu and Gd with HTTA alone as well as with its mixture with each of the crown ethers, 15C5 and 18C6, were determined and discussed.

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Abstract  

Hafnium and zirconium are separated from uranium using an anion exchange resin column. The two elements are then separated from each other using extraction chromatography and determined separately by precipitation as tetramandelate. The determination method was verfied by isotopic cilution technique. The method proved to be selective, quantitative (>99%) and gives an error of <±2%.

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Abstract  

The extraction of the trivalent lanthanides Eu, Tm and Yb(Ln) by crown ethers (CE) 12-crown-4 (12C4) and 15-crown-5 (15C5) in chloroform from perchlorate aqueous media of constant ionic strength is investigated. The effect of [H+], [CE] and [ClO 4 ] on the respective distribution ratio (D) is elucidated. Slope analysis of these results indicated that the extracted species are of the type Ln(OH) 2 + ·ClO 4 (CE)2. The extraction constants obtained are in the sequence 15C5>12C4 for the CE's and EuTm<Yb for the elements investigated. Based on the separation factors elucidated, Tm(III) and Yb(III) are separated from Eu(III) with high radiochemical purity; >99.5% by three (or four) successive extraction and strippings.

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Abstract  

Synergic extraction of trivalent Eu, Gd and Am from aqueous perchlorate medium has been studied using mixtures of thenoyltrifluoroacetone (HTTA) and 15-crown-5 or 18-crown-6 (CE) in chloroform at (25±1) °C. Slope analysis of the extraction results indicated a general formula of M(TTA)3·(CE)2 for the extracted species. The stability order took the sequence Eu(TTA)3·(CE)2>Am(TTA)3)·(CE)2>>Gd(TTA)3·(CE)2 with 15C5 and Am(TTA)3·(CE)2>Eu(TTA)3·(CE)2>Gd(TTA)3·(CE)2 with 18C6. The synergic factors, extracton constants and formation constants of the extracted species were determined and discussed in terms of the correspondence between cavity size of the crown ethers and ionic crystal radii.

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Abstract  

Extraction of WO 4 2– and ReO 4 by Adogen-381, tricaprylmethylammonium chloride, Hyamine 10-X, trioctylphosphine oxide or dibenzylsulphoxide in xylene from HNO3, HCl or H2SO4 acid medium was investigated. Based on the separation factors obtained, the separation of ReO 4 from WO 4 2– was elucidated. ReO 4 was separated from WO 4 2– in high radiochemical purity: >99.9% by three successive extractions and strippings using Adogen-381 from HCl or HNO3 acid medium.

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Abstract  

The effect of some environmental ligands and certain fertilizers on the complexation of strontium with humic acid wasinvestigated colorimetrically and radiometrically. The results indicate that Na2-EDTA, Na3-citrate and NaCl compete to complex strontium in solution with the sequence: chloride < citrate < EDTA while Na3-phosphate has the reverse behavior. In the case of nitrogen containing fertilizers, the results show that urea, Mg-ammonium nitrate and ammonium nitrate increase the availability of strontium to plants and microorganisms.

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Abstract  

The formation of Sr-humate precipitate was studied colourimetrically and radiometrically at different pH's. It was found that, increasing of the Sr2+ concentration or the pH value of the solution increases the precipitated complex. The competition effect of Mg2+, Ca2+, Ni2+, and Ba2+ on the complexation of Sr2+ by humic acid indicated that both Mg2+ and Ni2+ substitute Sr2+ in humate complex, while Ba2+ has a very little effect. In case of Ca2+, increasing of its concentration enhances the precipitation of Sr2+ with humic acid.

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Abstract  

Selective efficient method have been for separation of palladium by strong basic anion exchangers IRA-410 and IRA-900 from intermediate radioactive nitrate medium. The different conditions for exchange behaviour of palladium from [ILLW] solutions containing numbre of elements were investigated by batch technique. Selective recovery of palladium from the [ILLW] solution was achieved using column technique. The elution of palladium was carried out via reduction with formic acid where the rate of the reduction process was increased by decreasing the formic acid concentration till 50% followed by dissolving the separated palladium by nitric acid.

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Abstract  

In this work Strontium was separated selectively form, Pd2+, Ni2+ and Ca3+ using anionic resins of Amberlite type IRA-900 and IRA-410 from nitrate medium. The Separation of strontium by strongly basic anion exchangers IRA-410 and IRA-900 from simulated waste containing, Sr2+, Eu3+, Ce3+, Pd2+, Rh3+, Ru3+, VO2 2+, Fe3+, Cr3+, Ni2+, Al3+, Ca2+, and Cs+, in K2SO4/nitrate medium which adsorbed as strontium sulphate complex was achieved through ligand- ligan exchange. The elution of strontium carried out via loading the column with a solution of 0.03N EDTA in presence of 0.1N NaNO3 at pH7 where Sr2+ has low Kd value. An inductively Coubled Plasma — Optical Emission Spectrometry (ICP — OES) of ARL type model 3520, was used for elemental analysis.

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