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.
The isolation of minor uranium concentration from thorium matrix in HCl medium was investigated using liquid emulsion membrane
(LEM) containing TOPO as carrier, Span 80 as surfactant and sodium citrate as stripping agent. The factors affecting the stability
of the LEM were investigated. Different parameters affecting the permeation process were also studied. The results obtained
showed that, under certain conditions it is possible to isolate ca. 98% of U(VI) (120 ppm) in 1.0M HCl solution containing
Th (1000 ppm). The isolated U was found to be contaminated with less than 3% of Th.
Authors:S. Shawky, M. Abdel Geleel, and Ashraf Aly
Many studies have shown that water hyacinth (Eichhornia crassipes) roots can be used to accumulate high concentrations of organic as well as inorganic pollutants. They are currently used to remediate aquatic environments and aqueous solutions. In the present study, sorption of uranium from aqueous solutions by using dried roots of water hyacinth has been investigated. The sorption of uranium was examined as a function of initial concentration, pH, weight of roots and contact time. Five different concentrations 20, 40, 60, 80, and 100 μg . ml-1 were used. Sorption proves to be very rapid and depend on pH, weight of roots and concentration of uranium. Maximum sorption capacity of water hyacinth roots was 64,000 U6+ μg/g. The sorption of uranium by water hyacinth roots follows a Langmuir isotherm.
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
] on the respective distribution ratio (D) is elucidated. Slope analysis of these results indicated that the extracted species are of the type Ln(OH)
(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.
The extraction of Pd(II) by triphenylphosphine sulfide (Ph3PS) in benzene from nitric acid solutions has been investigated. The effect of different parameters on the extraction of palladium was studied. Based on the results, an equilibrium model is proposed. The stoichiometry of the extracted species was elucidated and found to be Pd(NO3)22Ph3PS. Possible interference with selected radionuclides that might exist in high level liquid waste was investigated and discussed.
The extraction behavior of octahedral and tetrahedral cobalt(II) complexes from aqueous nitrate medium was studied in the
system 8-hydroxyquinoline (HOX) and dibenzo-18-crown-6 (Db 18C6) or dibenzylamine (DBA) in chloroform at different temperatures
to evaluate the thermodynamic functions as well as the equilibrium constants of each reaction. The stoichiometry of the extracted
organic phase species were established to be Co(OX)2·Db18C6 for the octahedral cobalt and Co(OX)2·DBA for the tetrahedral cobalt.
The solid-state thermal reactions of 2,6-diamino-4-chloropyrimidine, 3,3-dimethoxybenzidine and of thiosemicarbazide with
each of 2-hydroxy-1-naphthaldehyde and 2,4-dihydroxybenzaldehyde in a mole ratio of 1∶1 produced (1+1) condensation products
(‘half units’). These solid state reactions have been studied by means of differential thermal analysis (DTA). The products
of the reactions were identified using elemental analysis and IR spectroscopy. Some kinetic parameters such as orders and
activation energies of the reactions were evaluated form the DTA curves.
It is found that from aqueous nitric acid media, Pd is highly extracted by chloroform solutions containing triphenylphosphine (Ph3P) and not extracted by triphenylphosphine oxide (Ph3PO) diluted with chloroform. The effect of diluent, nitric acid molarities, Ph3P concentration and temperature on palladium extraction by Ph3P was investigated. Slope analysis of the experimental results indicated that the main extracted species is in the form of Pd(NO3)2·2Ph3P.IR spectrum analysis of the extracted complex indicated the direct extraction of palladium as nitrate and bonding to phosphorus. Extraction of some fission product radionuclides from 2M HNO3 showed the selective extraction of palladium by Ph3P in chloroform.
Authors:R. Shabana, S. Khalifa, S. Abdalla, and H. Aly
Extraction of WO
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
was elucidated. ReO
was separated from WO
in high radiochemical purity: >99.9% by three successive extractions and strippings using Adogen-381 from HCl or HNO3 acid medium.