Development of O and NO Co-Doped Porous Carbon as a High-Capacity Mercury Sorbent.

In this study, a novel Hg adsorption strategy based on nonthermal plasma and porous carbon was proposed and tested. The O and NO in flue gas were used to activate porous carbon with auxiliary plasma. The plasma significantly increased the functionalities on the carbon surface, and it has a negligible effect on the textural properties of porous carbon. The O/NO co-doped porous carbon was used to remove elemental mercury (Hg). The sample functionalized by plasma in 4% O and 200 ppm NO (balanced with N) for 3 min exhibited superior Hg adsorption ability, which could be assigned to the formation of a large amount of C═O, C-NO, and C-NO. O, NO, and HCl have a positive effect on Hg adsorption, whereas SO and HO have an inhibitory effect on Hg removal. The equilibrium Hg adsorption capacity of optimal O/NO co-doped porous carbon was found to be 12315 μg/g, which was far greater than that of brominated activated carbon (1061 μg/g). Density functional theory was used to investigate the mechanism responsible for Hg adsorption. C═O and C-NO improved the interaction of Hg with neighboring carbon sites. C-NO could react with Hg by forming HgO.