Microwave irradiation for regeneration of granular activated carbon (GAC)

The behaviors of heating-up and drying of activated carbon by microwave irradiation were studied and described quantitatively. The relationship between regeneration efficiencies of GAC and those factors such as microwave power, irradiation time and dose absorbed by GAC was derived and analyzed through orthogonal test. The influence of MW treatment on the acidic and basic groups of GAC was studied; the pore structures of exhaust GAC and MW treated GAC were compared. Results show that the temperature of GAC can reach 1000°C by MW irradiation in a few minutes. The main factor affecting the iodine amount is irradiation time and the optimal regeneration conditions are 400 W and 2 min. The surface acidic groups are removed due to their decomposition, and the basic characteristic becomes prominent. Compared with exhaust GAC, the specific area and pore volume both increase by 100%. Moreover, MW mostly affects the pores with diameter less than 5 nm. The experiment shows that the microwave irradiation method is practical for regeneration of activated carbon.