Thermal behaviors and regeneration of activated carbon saturated with toluene induced by microwave irradiation

Microwave irradiation is an effective way to regenerate the activated carbon after adsorption and separation of waste. In this work, activated carbon saturated with toluene was efficiently regenerated by microwave irradiation. The maximum regeneration ratio of 77.2% was obtained under the following optimal operation conditions: saturated activated carbon of 5.01 g, microwave power of 500 W, carrier gas N₂ flow of 60 mL/min, and microwave irradiation time of 180 s. It was found that the higher microwave power may result in self-burning of activated carbon due to the presence of traces of oxygen, which might slightly deteriorate the pore structures of activated carbon. On the other hand, the lower microwave power cannot start desorption of toluene or might cause re-adsorption. The introduction of N₂ flow during regeneration was necessary to release the desorbed toluene from activated carbon, but it might cool the adsorption system under a much higher N₂ flow rate.