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

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% O_α 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.