Kinetics of uranium sorption onto weakly basic anion exchangers

Two weakly basic anion exchangers were investigated with respect to the kinetics of uranium sorption from drinking water. For theoretical description the combined film-particle diffusion model was applied. The two essential parameters in this approach, the liquid mass transfer coefficient βL as well as the solid-phase diffusion coefficient Ds were determined from experiments and from comparison of experimental data and theoretical developments. Liquid-phase mass transfer coefficients were found to be in the order of magnitude of βL = 10−5 m/s, diffusion coefficients in the exchanger phases amounted to the range of Ds = 10−12 m2/s for the acrylic exchanger Amberlite IRA 67 and Ds = 10−13 m2/s for the polystyrene resin Lewatit MP 62. Because of the trace concentration level of uranium species both steps affect the overall rate of sorption and none of them can be neglected.