Effect of flue gas on elemental mercury removal capacity of defective carbonaceous surface: A first-principles study

The atomic interaction between elemental mercury in the flue gas and defective carbonaceous surface is studied by the first-principles calculation. The defective carbonaceous surface is modeled by a nine-fused benzene cluster with two adjacent atomic vacancies. The results indicate that vacancies can increase the activity of their neighboring carbon atoms. However, the vacant sites present the decrease in mercury removal capacity, which is different from the behavior of the defective carbonaceous surface with only one atomic vacancy. In addition, flue gas molecules (FGMs) including CO, CO2, NO, NO2, SO2 and H2O, are examined to evaluate the influence on the mercury removal of the defective carbonaceous surface. The calculated results demonstrate that different adsorption behaviors for Hg-0 occur on the defective carbonaceous surface due to the presence of FGMs. It can be found that CO may enhance the mercury removal capacity of the defective carbonaceous surface when its concentration is higher than that of Hg-0. Meanwhile, SO2 presents the remarkable positive effect on the mercury removal efficiency at the vacancy. On the contrary, the presence of CO2, NO, NO2 and H2O leads to the increase in the adsorption energies of mercury on the defective carbonaceous surface.