Effects of microwave regeneration of activated carbon on its SO₂ adsorption

The microwave regeneration of SO₂ loaded activated carbon (AC) and its circulation adsorption characteristics were studied. The effects of microwave regeneration on the pore texture and surface chemistry of AC were analyzed by SEM, low temperature N₂ adsorption, elemental analysis and Boehm titration. The results show that microwave irradiation is an effective regeneration method. In the suitable regenerative power, after many circulation adsorption/regeneration, the AC still remains high adsorption capacity. After 17th circulation, the adsorption capacity of AC is still higher than the primitive AC. Hower, there is obviously weight loss for AC during the regeneration because of the reaction between C and H₂SO₄. After first regeneration, the surface acidic functional groups of the AC almost decompose at high temperature, and the surface basic functional groups increase, so the SO₂ adsorption capacity of AC is enhanced. After several adsorption/regeneration circulations, the surface acidic functional groups and basic functional groups remain stable, while the pore structure of AC becomes long and narrow for the activation of regeneration. And the specific surface area and volume of micropore increase, which benefits the SO₂ adsorption on AC.