Efficiency evaluation of thermal, ultrasound and solvent techniques in activated carbon regeneration

The regeneration of diclofenac saturated activated carbon was studied and compared by thermal, solvent and ultrasound techniques in this work. Thermal regeneration was performed at 673 K in atmospheric air for one hour. Different proportions of solvents (ethanol, ethyl acetate and H₂O) were used to evaluate the regeneration of the sorbent solid. Ultrasound treatment was tested by varying the time (5 and 15 min) and bath temperature (298 and 323 K). With the highest levels of regeneration for each technique employed, regeneration cycle tests were conducted. With the adsorption capacity recovery limit set at 60%, 8 regeneration cycles were achieved. At the end of the 8th regeneration cycle, the thermal technique made it possible to maintain the adsorption capacity at 75%. Using the water/ethanol (50:50) solvent mixture, after 8 cycles, 64% of solid regeneration was obtained. With the ultrasound technique, in the 5th cycle the solid regeneration capacity was reduced to 65%, remaining constant until 8°. The sorbent solid was characterized by TGA, N₂ adsorption, FTIR and sem.