Mercury emitted from coal combustion has attracted more and more attention.The activated carbon(AC)injection is a commercially available technology for cleaning mercury from flue gases of coal-fired power plants.Various chemical impregnation methods have been suggested to improve the mercury removal efficiency but not to increase the dosage of sorbent,resulting in excessive consumption of chemical reagent and secondary pollution.Aim to develop a cost-effective sorbent for removing gaseous mercury,a novel treatment method(non-thermal plasma treatment)for carbon-based sorbent was initially proposed for capturing mercury from flue gases of coal-fired power plants.Activated carbon(AC)was treated by non-thermal plasma in air or HCl/Cl2 to added O/Cl functional groups.The test of mercury capture capacity was accomplished in alaboratory bench to compare the treated and untreated sorbent,and the samples were characterized with ultimate analysis,BET surface area and XPS technique to discuss the correlation of sorbents physical and chemical properties with the mercury adsorption mechanisms.The results showed that AC treated with non-thermal plasma has higher mercury removal efficiency,and longer treatment time results in higher efficiency.The main reason is that the non-thermal plasma treatment increased the O/Cl active sites of sorbents.Through air non-thermal plasma carbonyl groups(C=O)and ester groups(C(O)-O-C)of AC,which play an important role in mercury absorption,and ester groups predominates mercury removal efficiency at higher temperature.While HCl/Cl2 plasma treated sorbents have a better performance than air,it implied that mercury is easier adsorbed by Cl active sites.Comparing the amount of added Cl and the amount of adsorbed mercury,it suggests that non-thermal plasma make the Cl active sites more efficiency on mercury removal than the other methods.By further analysis,it was found that increasing the active sites of AC are more effective than increasing the surface area for improving the mercury removal efficiency,and the active sites on the exterior surface of sorbent play a more important role in affecting the efficiency than the internal surface.The non-thermal plasma treatment is a potential method for improving the mercury adsorption performance of sorbents.