Effect of Halide Impregnation on Elemental Mercury Removal of Activated Carbons

Activated carbons ( ACs ) were impregnated with potassium halides ( KX ) to enhance the removal efficiency of elemental mercury (Hg 0 ). In this work, the impregnation effect of potassium bromide ( KBr ) and potassium iodine ( KI ) were investigated. The surface properties of KX‐ACs were determined by scanning electron microscopy ( SEM ) and energy dispersive spectroscopy ( EDS ). The pore structures and total pore volumes of the KX‐ACs were analyzed using the N 2 /77 K adsorption isotherms. The Hg 0 removal efficiency of KBr‐ACs and KI‐ACs was studied under simulated flue gas conditions. The effects of KI and KBr loading, adsorption temperature, and flue gas components on Hg 0 removal efficiency were also investigated. The results showed that the Hg 0 removal efficiency of the ACs was significantly enhanced by KI or KBr impregnation, and KI‐ACs showed higher Hg 0 removal efficiency than KBr‐ACs under the same conditions. An increase in KI or KBr loading and higher adsorption temperatures improved the Hg 0 removal efficiency, indicating that chemisorption occurred due to the reaction between X − and Hg 0 . The lower extent of Hg 0 removal exhibited by the KBr‐ACs than by the KI‐ACs was due to the difficulty of Br 2 formation on the surfaces.