Adsorption behaviour of the individual tracer ions:134Cs(I),85,89Sr(II),131,133Ba (II),90Y(III),141Ce(III),152,154Eu(III),95Zr(IV),175,181Hf(IV),95Nb(V),60Co(II),115Cd(II),99mTc(VII), and131I(-I) on charcoal impregnated with stannic chloride from Hcl solutions, was investigated. Batch equilibrium distribution coefficients of the respective ions indicated strong anion exchange properties towards impregnated charcoal. The column breakthrough sorption capacity was of the order of 0.62–0.66 meq·g–1 of dry adsorbent. Small chromatographic columns of impregnated charcoal could achieve rapid and quantitative separation procedures in HCl medium. Strongly adsorbed anions such as TcO
and I– ions could be eluted with NH4SCN and NH4NO2 eluents, respectively.
This paper reports a radiochemical study of the kinetics of ion exchange of Na+ and Cs+ with H+ on hydrous titanium dioxide. The experimental conditions are set to favor the particle diffusion mechanism only, and this is confirmed by the Bt versus t plots. On the basis of these studies the various physical parameters such as the effective diffusion coefficients, activation energies and entropies of activation have been evaluated. Tentative explanations are given for these results, from which some conclusions are drawn.
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.
Authors:M. El-Absy, M. El-Enein, M. Raieh, and H. Aly
12-molybdocerate(IV) gel labelled with99Mo has been prepared via isotope exchange between a column of inactive molybdate matrix and a mobile solution of99-Mo-sodium molybdate(VI) in 0.1 mol·dm–3 HNO3. The composition and nature of the reaction mixture, concentration of Mo(VI) in the reactants, reaction temperature and/or drying temperature of the gel matrix on the exchange yeild of99Mo and time of reaction are explored using the batch equilibration and/or the chromatographic column methods. The obtained material is evaluated for use in preparation of elution-type99Mo-99mTc generators.
Authors:M. El Absy, I. El Naggar, M. Hamid, and H. Aly
The distribution of UO
and Th4+ in nitric acid media on crypomelane-type hydrous manganese dioxide (CRYMO) has been investigated by batch equilibrations and column break-through techniques. The parameters studied involve the media composition and concentrations of HNO3, NaNO3, UO
and Th4+. It is found that Th4+ is more strongly adsorbed on CRYMO than UO
with sufficient differences for chromatographic separation from each other. Uranium was quantitatively eluted from a CRYMO column with 0.1M HNO3. Th4+ has been recovered by using 1M HNO3 as eluent.
Neutron irradiated 12-molybdocerate(IV) is evaluated as a column matrix for use in preparation of small chromatographic column type99mTc generators. Greater than 87% of the generated99mTc activity is immediately and reproducibly eluted with passing 10 cm3 of saline or chromated saline solutions through 3.0 g of molybdocerate column bed at flow rates of about 1.0 cm3/min. The elution performance of99mTc does not drastically change with increasing the drying temperature and/or the particles sixe of the column matrix in the range investigated. Saline eluent containing 5·10–5M CrO
increases the radiochemical purity of the eluate to >98% TcO
. Radionuclidic and chemical purities of the eluates satisfy the specifications for use in nuclear medicine.
The preparation of insoluble 12-molybdocerate(IV) from99Mo of low specific activity, produced by thermal neutron irradiation of MoO3, is described. Samples of the material are dried at 50, 100 and 200°C and used as column matrices from which the generated99mTc activity is periodically eluted with saline solution or saline solution containing 5·10–5M K2CrO4 as an oxidant. The elution yields of99mTc are high and reproducible (95–81%) with radionuclidic purity 99.98%. Both chemical and radiochemical purity (as TcO
) of the eluates decrease with increasing drying temperature of the column matrix. Using chromated saline solution as eluent improves the radiochemical purity of the99mTc eluate.
Self-diffusion coefficients for chloride ion were measured as a function of chloride ion capacity in solutions of varying acdity using particles of hydrous ceric oxide heated at 50, 200 and 400°C. The measured self-diffusion coefficients are dependent only upon the total chloride ion capacity. At the same capacity, self-diffusion coefficients are almost the same for ceria particles heated at different temperatures. The trace component diffusion coefficients of chloride ion in the nitrate-form of the oxide, dried at 50°C, were also measured. Under the same conditions, the self-diffusion coefficients are somewhat higher or close to the trace component diffusion coefficient for the sample dried at 50°C.
Authors:M. El-Absy, H. Aly, M. Mousa, and M. Mostafa
Fission-produced 131I and 103Ru radionuclides have been separated sequentially by distillation from H2SO4 of controlled chemical composition. The thermal-neutron irradiated uranium trioxide targets were digested in 2M NaOH solution
and then, the supernatant solution was acidified to 20% H2SO4 with addition of a few drops of H2O2 solution. On boiling for 3.5 hours, ≥99.99%131I was volatilized, passed through 3M H2SO4 traps, and then collected in 0.1M NaOH + 0.01% Na2S2O3 solution with a recovery yield of 73.6%. The product radionuclide had high radiochemical and radionuclidic purities. After
separation of 131I, the fission-product solution was acidified to 40% H2SO4 acid containing KMnO4 as an oxidant and boiled for 40 minutes. Ruthenium nuclides were volatilized and collected in 0.1M NaOH solution. Gamma-ray
spectrometry showed that the separation and the recovery yields of 103Ru were ≥99.99 and 65%, respectively, with ~92% radionuclidic purity, measured immediately after separation. The radionuclides
of 132I and 106Rh were the main contaminants detected in the obtained 103Ru product solution.
Authors:M. Mostafa, M. El-Absy, M. Amin, M. El-Amir, and A. Farag
Potassium nickel hexacyanoferrate(II) matrix was prepared and characterized. Purification of neutron-activation 99Mo–molybdate(VI) solutes from some residual cross-contaminant radionuclides including 134Cs, 86Rb, 124Sb, 60Co and 51Cr was carried out onto small chromatographic columns of the matrix (each of 1.0 g). Gamma-ray spectrometric analysis data
showed that the purification process was not affected by either Mo(VI) concentrations (0.13 and 0.02 M Mo) in the feeding
solution of 3.5 M NaNO3 at pH 9.5 or flow rates (0.2 and 5.0 mL/min) at room temperature. Molybdenum(VI) average loss onto the column matrix did
not exceed 7.7 × 10−2 mmol Mo. Except for 51Cr, the matrix has very high selectivity for 134Cs, 86Rb and 124Sb with ~50% 60Co elimination. The obtained data were briefly discussed.