Radionuclide Removal from Aqueous Solutions Using Oxidized Carbon Fabrics

The adsorption of actinide ions (Am(III) and U(VI)) from aqueous solutions using pristine and oxidized carbon fabrics was investigated by means of batch experiments at different pH values (pH 4, 7 and 9) and temperatures (25, 35 and 45 °C) under ambient atmospheric conditions. The experimental results indicated that both the pH and the fabric texture affected the adsorption rate and the relative removal efficiency, which was 70% and 100% for Am(III) and U(VI), respectively. The K_d (L/kg) values for U(VI) were generally found to be higher (2 < log₁₀(K_d)< 3) than the corresponding values for Am(III) adsorption (1.5 < log₁₀(K_d) < 2). The data obtained from the experiments regarding the temperature effect implied that the relative adsorption for both actinides increases with temperature and that adsorption is an endothermic and entropy-driven reaction. The application of the fabrics to remove the two actinides from contaminated seawater samples showed that both the relative removal efficiency and the K_d values decreased significantly due to the presence of competitive cations (e.g., Ca²⁺ and Fe³⁺) and complexing anions (CO₃^2-) in the respective waters. Nevertheless, the removal efficiency was still remarkable (50% and 90% for Am(III) and U(VI), respectively), demonstrating that these materials could be attractive candidates for the treatment of radionuclide/actinide-contaminated waters.