Fundamental Mechanisms of Mercury Removal by FeCl<sub>3</sub>- and CuCl<sub>2</sub>-Impregnated Activated Carbons: Experimental and First-Principles Study
Dong‐Hee Lim, Sinang Choi, Jeongmin Park, Thillai Govindaraja Senthamaraikannan, Yuri Min, Sang-Sup Lee
Abstract
Experimental and first-principles studies were conducted to understand the adsorption mechanism of elemental mercury on FeCl3- and CuCl2-impregnated activated carbons. Activated carbon was impregnated with either FeCl3 or CuCl2, and their adsorption of elemental mercury was evaluated using a laboratory-scale fixed-bed system. The fixed-bed tests were carried out by injecting only nitrogen gas to investigate the interaction between mercury and the chemical compound impregnated on the activated carbon. The test temperature was 140 °C to simulate the temperature in a particulate matter control device of full-scale facilities, such as coal-fired power plants and waste incinerators. Based on the results, CuCl2-impregnated activated carbons showed much higher adsorption efficiencies for elemental mercury than both activated carbons and FeCl3-impregnated activated carbons. Density functional theory (DFT) calculations revealed that the mercury adsorbates were adsorbed more strongly on the CuCl2(110) surface than on the FeCl3(001) surface. Electronic property analyses revealed that the CuCl2 surface was more efficient as a mercury removal adsorbent because more electrons were shared between Hg- and Cu-influenced Cl bonds than those between Hg- and Fe-influenced Cl bonds, which resulted in the stronger Hg adsorption of the former.