Uranium sorption on cork biomass

This work presents the effect of the pre-treatment of cork biomass with a hydrochloric acid solution on its sorption affinity towards uranium. The results show that the conversion of cork biomass into the H-form by the acid wash allowed to increase the sorption capacity towards uranium more than twice, due to the increase of the concentration of strong acidic and weak acidic groups on its surface. The optimum pH for uranium sorption was 5.0–5.2 for the original and 5.5–7.0 for the H-form biomass. The adsorption isotherms for uranyl ions on the natural and H-form cork biomass were determined. Finally, the kinetics of uranium adsorption on both biomasses was studied and a second-order model was fitted to the experimental data. It was found that the adsorption is faster for the H-form (k = 0.196 min−1) than for the original biomass (k = 0.057 min−1).