Removal of Elemental Mercury from Flue Gas Using Cobalt-Containing Biomaterial Carbon Prepared from Contaminated Iris sibirica Biomass

Iris sibirica biomass (ISBM) used for cobalt (Co) pollution remediation was prepared by one-step pyrolysis and employed to remove elemental mercury (Hg⁰) from flue gas. Results showed that the ISBM pyrolyzed at 700 °C (ISBM700) exhibited good Hg⁰ removal performance (about 86%) at 150 °C. The existence of NO and O₂ facilitated the removal of Hg⁰, while SO₂ and water vapor inhibited it. Characterization analysis (including N₂ adsorption-desorption, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectrometry) showed that ISBM700 has a relatively higher specific surface area, a quantity of lattice oxygen derived from well-dispersed amorphous-phase CoO _x , and abundant oxygen functional groups. A Mars-Maessen mechanism is thought to be involved in the Hg⁰ removal process. The adsorbed Hg⁰ could be oxidized to HgO by the surface oxygen species derived from CoO _x , and then, the consumed surface oxygen species can be replenished by O₂. Therefore, the Co-contaminated I. sibirica biomass (CCIB) from phytoremediation could be utilized for Hg⁰ removal after being pyrolyzed instead of any chemical modification.