Ultra-high adsorption of Hg 0 using impregnated activated carbon by selenium.

Activated carbon was one of the main adsorptions utilized in elemental mercury (Hg 0 ) removal from coal combustion flue gas. However, the high cost and low physical adsorption efficiency of activated carbon injection (ACI) limited its application. In this study, an ultra-high efficiency (nearly 100%) catalyst sorbent-Se x /Activated carbon (Se x /AC) was synthesized and applied to remove Hg 0 in the simulated flue gas, which exhibited 120 times outstanding adsorption performance versus the conventional activated carbon. The Se x /AC reached 17.98 mg/g Hg 0 adsorption capacity at 160 °C under the pure nitrogen atmosphere. Moreover, it maintained an excellent mercury adsorption tolerance, reaching the efficiency of Hg 0 removal above 85% at the NO and SO 2 conditions in a bench-scale fixed-bed reactor. Characterized by the multiple methods, including BET, XRD, XPS, kinetic and thermodynamic analysis, and the DFT calculation, we demonstrated that the ultrahigh mercury removal performance originated from the activated Se species in Se x /AC. Chemical adsorption plays a dominant role in Hg 0 removal: Selenium anchored on the surface of AC would capture Hg 0 in the flue gas to form an extremely stable substance-HgSe, avoiding subsequent Hg 0 released. Additionally, the oxygen-containing functional groups in AC and the higher BET areas promote the conversion of Hg 0 to HgO. This work provided a novel and highly efficient carbon-based sorbent -Se x /AC to capture the mercury in coal combustion flue gas. Graphical abstract Selenium-modified porous activated carbon and the interface functional group promotes the synergistic effect of physical adsorption and chemical adsorption to promote the adsorption capacity of Hg 0 .