Recyclable MnCl2-Fe2O3@CNT as Sulfur and Water-Resistant Sorbent for Gaseous Elemental Mercury Removal from Coal Combustion Flue Gas

Mercury poses serious hazards to human health. Carbon nanotube (CNT) is a potential material for elemental mercury (Hg0) adsorption removal, however, it shows susceptibility to SO2 and H2O. Herein, CNT is first decorated with Fe2O3 then modified with MnCl2 (MnCl2-Fe2O3@CNT) to enhance SO2 and H2O resistance. The Hg0 removal performance and physical–chemical properties of samples are comprehensively studied. MnCl2(10)FeCNT (10 wt% MnCl2 content) has a high specific surface area (775.76 m2·g−1) and abundant active chlorine (35.01% Cl* content) as well as oxygen species (84.23% Oα content), which endows it with excellent Hg0 adsorption capacity (25.06 mg·g−1) and good SO2 and H2O resistance. Additionally, the superparamagnetic property can enable MnCl2(10)FeCNT to be conveniently recycled. After fifth regeneration, MnCl2(10)FeCNT can still achieve >90% Hg0 removal. The abundant active chlorine and oxygen species over MnCl2(10)FeCNT are responsible for Hg0 removal with HgCl2 as the primary product. This work demonstrates the enhancement of CNT’s resistance to SO2 and H2O by Fe2O3 and MnCl2 modification, which has potential application in flue gas mercury removal.