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

Abstract

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 CoOx, 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 CoOx, 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.