Development of O2 and NO Co-Doped Porous Carbon as a High Capacity Mercury Sorbent

In this study, a novel Hg-0 adsorption strategy based on nonthermal plasma and porous carbon was proposed and tested. The O-2 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-2/NO co-doped porous carbon was used to remove elemental mercury (Hg). The sample functionalized by plasma in 4% O-2 and 200 ppm NO (balanced with N-2) for 3 min exhibited superior He adsorption ability, which could be assigned to the formation of a large amount of C=O, C-NO, and C-NO2. O-2, NO, and HCl have a positive effect on He adsorption, whereas SO2 and H2O have an inhibitory effect on Hg removal. The equilibrium Hg adsorption capacity of optimal O-2/NO co-doped porous carbon was found to be 12315 mu g/g, which was far greater than that of brominated activated carbon (1061 mu g/g). Density functional theory was used to investigate the mechanism responsible for Hg-0 adsorption. C=O and C-NO improved the interaction of He with neighboring carbon sites. C-NO2 could react with Hg-0 by forming HgO.