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- Author or Editor: H. Aly x
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Abstract
Three different alternatives are applied for the determination of the stability constants of zirconium and hafnium complexes with 2-methyl lactic acid using cation exchange. Calculations based on the exchange equilibria of the highly charged metal cations and the positively charged ligand complexes rather than that of the hydrolysed complex species are worked out according to SCHUBERT and FRONAEUS, respectively. The third alternative adopted in this work, is principally based on the consideration of all complexed species produced by hydrolyses in the aqueous phase. The B-values obtained by the different methods are intercorrelated and discussed.
Abstract
The kinetics of extraction of U(IV) by TBP in kerosene was investigated using a stirred Lewis cell. The effect of the different parameters affecting the extraction rate as well as temperature were separately investigated. The rate equation deduced from the experimental results show that the extraction of U(IV) is first order dependent on TBP concentration while it is of zero order with respect to U(IV), H+, NO 3 – and HNO3 concentrations. The data obtained show that the extraction process is governed by chemical reactions taking place at teh interface.
Abstract
Extraction of Co(II) from perchlorate aqueous media by mixtures of thenoyltrifluoroacetone and triphenylarsine oxide or triphenylphosphine oxide in chloroform has been studied. It is found that the presence of these oxides enhances the extraction of Co(II). Synergic factors and formation constants were calculated and interpreted in the light of the electron donating properties of these oxides.
Abstract
Heterogeneous isotope exchange between hydrated stannic oxide and stannous chloride in 0.1M HCl solution has been studied as a function of the stannic oxide, stannous chloride, and chloride ion concentrations, and temperature. The exchange process is a second-order reaction, which is independent of the chloride ion concentration, with a mean rate constant, k, of 2.31 dm3 mol–1·min–1. The activation energy of the isotope exchange process was found to equal 3.62 kcal·mol–1. Possible use of this system, SnCl2/SnO2·xH2O, as basis for a113Sn-113mIn generator is suggested.
Abstract
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.
Abstract
Comparative studies between column and batch liquid emulsion membrane techniques based on HDEHP/HCl system were carried out to develop a system for isolation of234Th from natural uranium. For column investigations a spray column was constructed and used with two different modes. In the first mode the feed solution was circulated through the membrane while in the second mode the membrane phase was circulated through the feed solution. The results showed that, kinetically, the equilibrium for thorium separation using batch technique is faster than the continous column system. Quantitative permeation of thorium was achieved within one minute of mixing whereby the permeation of uranium reached equilibrium after 3 minutes with a permeation percentage less than 6%. A procedure was developed to separate234Th from natural uranium with high radiochemical purity of more than 98%.
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.
Abstract
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.
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.
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.
