Preliminary investigation on regeneration of simulated radionuclide-contaminated activated carbons by microwave irradiation

This work investigates the feasibility of microwave (MW) irradiation for the regeneration of activated carbon (AC) spent with cesium. Adsorption batch experiments were carried out using commercially available granular activated carbon (Norit GAC 830). The Cs-saturated AC was treated using a controllable bench-scale 2.45-GHz MW oven at the power of 440 W for 3 min. The adsorption-regeneration cycle was repeated three times. The potentiality of the MW regeneration was assessed as regeneration efficiency (RE) and weight loss percentage of the AC samples during the adsorption/regeneration cycles. Textural properties of saturated and regenerated ACs were also evaluated by nitrogen adsorption isotherms at 77 K. Overall, results demonstrated a relatively low adsorption capacity for cesium, although the dielectric nature of the GAC allowed a rapid and effective regeneration process. Specifically, the weight loss percentage was found less than 2% jointly with an important increase in RE after 3 regeneration cycles. A preservation of the pore structure of regenerated ACs during MW regeneration was also observed.