Kinetics of uranium (VI) ions adsorption on activated charcoal from aqueous solutions

The temperature and concentration dependence of the kinetics of uranium(VI) ions adsorption onto activated charcoal from aqueous solutions has been studied. The adsorption proceeds via a rather fast stage followed by a slower one, with activation energies of 5.41 and 17.46 kJ . mol-1 respectively. The diffusion of uranium ions into the pores of the activated charcoal controls the kinetics of adsorption which follows the Langmuir isotherm equation in the concentration range studied. The adsorption equilibrium constant, kc has been derived at temperatures between 283 K and 323 K as well as Δ G, Δ H and Δ S. The results indicate that the adsorption of uranium ions on activated charcoal is an endothermic process. (orig.)