Chelation studies of cobalt(III) with 1,2 bis(beta-aminoethoxy)ethane N,N,N',N' sodium sulfonate triacetic acid (ASTA) were
performed. The results showed the effectiveness of ASTA as a chelating agent by using: molar ratio, continuous variation and
slope ratio methods. Stable complex 1∶1 was formed at pH from 6.0 to 10.5. Solutions of Co-ASTA chelate of different molar
ratios at pH 6.5 and 8.0 were irradiated by different gamma-radiation doses. The results showed a linear decrease of absorbance
with gamma-radiation dose which can be utilized as a dosimeter for low dose rate measurement in the range studied. A proposed
radiolytic mechanism is discussed. The degradation of the ASTA ligand has been related to hydroxyl radical attack.
Authors:M. Abdel Raouf, K. Farah, M. Nofal, and A. Alian
Sorption of124Sb(III) from benzene, toluene, o-xylene and nitrobenzene on treated fly ash, pyrolysis residue and bentonite clay was studied at room temperature using the batch method. In comparison to a former study for the sorption of124Sb(V), the results revealed relatively higher sorption of the trivalent state than the pentavalent one. According to the type of the nonpolar solvent used, the order of uptake of the radioactive isotopes was often o-xylenetoluene>benzene. The sorption tendency of the sorbents used towards the radionuclides was: bentonitepyrolysis residue>treated fly ash. Sorption from an aqueous medium on the same sorbents has also been investigated for124Sb(III) compared to124Sb(V),152Eu(III) and their mixtures. The obtained results showed that the order of uptake of the different radionuclides was: Eu(III)>>Sb(III)>Sb(V)>mixture. The investigation was extended to the desorption studies of these radionuclides in the acidic and the neutral media from the dried radioactivity loaded sorbents.
Kinetics and equilibrium studies on the sorption of uranium and thorium ions were carried out from nitric acid solutions by
tri-n-butyl phosphate (TBP) loaded supported sorbent, commercially known as Egy-Sorb, using batch technique. Analysis of the
rate data in accordance with three kinetic models revealed that the particle diffusion process was the rate determining mechanism
and the sorption process of the metal ions onto impregnated sorbent follows first order reversible kinetics. The values of
the first order rate constants, the rate constants of intraparticle transport, and the particle diffusion coefficients for
the uranium and thorium ions were determined from the graphical representation of the proposed models. Experimental isotherms
of both ions were successfully fit to Langmuir and Freundlich isotherm models over the entire concentration range studied.
The effect of temperature on the equilibrium distribution values has been utilized to evaluate the changes in standard thermodynamic
Authors:Samira Mousa, Amal Altakrory, M. Abdel Raouf, and A. Alian
The effect of water-miscible alcohols and acetone on the extraction and separation of Cd and Zn chlorides by TOPO was systematically
investigated. The maximum extraction of Zn chloride with 0.1 M TOPO decreases in the order: acetone>methanol>ethanol>2-propanol>2-butanol.
For alcohols, the sequence of decreasing extractability is thus parallel to the order of their dielectric constants. This
can be explained by the increase of HCl extraction by TOPO in the same direction. The presence of additives in the polar phase
prevents the formation of a bulky white precipitate encountered during extraction of ZnCl2 from pure aqueous solutions. A decrease of Cd chloride extraction was generally noticed in presence of additives; this is
more noticeable for the longer chain alcohols. The highest separation factor (E for ZnCl2 and CdCl2 in 0.48M HCl is obtained from 30% methanol (13.8 compared to about 3.8 in absence of methanol) and from 10–20% acetone where
it reaches 30.