Promoting Mercury Removal in High Humidity Environments by Hydrophobic Modified Activated Carbon with Methyl Functional Group

Abstract

When employing activated carbon (AC) injection technology to absorb elemental mercury (Hg0) from the flue gas of coal-fired power plants, the existence of H2O can readily impede the Hg0 adsorption efficiency of AC. Therefore, by utilizing hexamethyldisiloxane vapor deposition modified AC, the adsorption capacity of AC for Hg0 in high humidity environments is enhanced. On the basis of experimental data, it can be determined that the contact angle of water for hydrophobically modified AC increases from 42° to 143°, the simulation results of water channels show that the number of water molecules escaping from the modified activated carbon loaded with hydrophobic functional groups has increased by 325%, when water vapor content was 30%, mercury removal efficiency of modified activated carbon rose from 58.82% to 89.60% compared with activated carbon. In high humidity environments, NO and SO2 can produce corresponding acids for oxidizing Hg0, thereby enhancing the adsorption efficiency of Hg0, while NH3 completes with Hg0 for the active sites on the surface of AC, thus having an inhibitory effect.

Keywords: Gas deposition method, Hydrophobic modification, Mercury Removal, Element mercury