Promoting mercury removal in high humidity environments by hydrophobic modified activated carbon with methyl...

The H₂O content in the flue gas seriously inhibits the application of activated carbon injection adsorption mercury technology. Hydrophobic activated carbon was prepared by hexamethyldisiloxane (HMDSO) vapour deposition, the contact angle of water for hydrophobically modified AC increased from 42° to 143°, and H₂O adsorption capacity decreased from 17.28 mg/g to 3.05 mg/g when relative humidity was 95%. The simulation results of water channels show that the number of water molecules escaping from the modified AC loaded with hydrophobic functional groups increased by 325%. When the water vapour content was 30%, the mercury removal efficiency of modified AC increased from 58.82% to 89.60% compared with AC, and the adsorption capacity increased by 10.6 μg/g. In high-humidity environments, NO and SO₂ can produce corresponding acids for oxidising Hg⁰, thereby enhancing the adsorption efficiency of Hg⁰, while NH₃ completes with Hg⁰ for the active sites on the surface of AC, which has an inhibitory effect.