M.S. Abd El-Ghany Nuclear Materials Authority, P.O.Box 530 El-Maadi, Cairo, Egypt E-mail: omneya@link.net
Summary: Uranium equilibrium distribution between the tributyl phosphate (TBP) impregnated Amberlite XAD-4 polymeric resin support and 5.5 N nitrate aqueous acid solution was converted from curve to straight line by the Langmuir equation. From the resultant straight line, the constants “Q” and “K” were determined to be used in the mathematical models validities. The values of these constants were found to be 223.312 and 0.3919 respectively. On the other hand, the adsorption and elution kinetics data resulting from the fractional approach to equilibrium “Y” were used in calculations for evaluating the diffusion control during uranium adsorption (from nitric acid medium and the nitric acid/aluminum nitrate medium) and during the elution. The corresponding mass transfer coefficients were then determined. The mathematical model validity for diffusion through liquid film reveals that another rate process controlling the mass transfer, while the diffusion through the combined liquid film and solid indicates validity the equation of controlling the mass transfer rate process. On the other hand, the mass transfer rate during the elution step was controlled by the diffusion through solid, however, the diffusivity inside the TBP impregnated resin beads “Dp” was 165.2 x 10-12 m2/s. Key words: Uranium, tributyl phosphate, Amberlite XAD-4, impregnated resin, nitric acid, adsorption, elution, kinetics, diffusion, liquid film, mathematical models. |
