The first principles study: removal of elemental mercury by MoS 2

Abstract Emission of elemental mercury (Hg 0 ) from industrial flue gases poses grave threats to environmental well-being due to its volatility, high toxicity, and persistence. Molybdenum disulfide (MoS 2 ) has been a popular material for Hg 0 removal, but the removal mechanism remains to be investigated. In this work, the density functional theory (DFT) calculations were employed to examine the removal mechanism of Hg 0 by MoS 2 , and the calculations revealed that the adsorption of Hg 0 on MoS 2 involves both physical and chemical processes, leading to the formation of stable HgS. The calculated adsorption energies indicate stronger adsorption at the top site compared to the bridge site. Typically, flower-like MoS 2 was synthesized via a hydrothermal method and characterized using XRD and SEM, confirming its unique three-dimensional spherical morphology composed of regularly arranged two-dimensional nanosheets. The synthesized MoS 2 demonstrated a high efficiency in removing mercury (85%) at a temperature of 120 °C under simulated flue gas conditions (pure N 2 ); however, as SO 2 appeared, the efficiency dropped to 63%, indicating competitive adsorption for active sites. The findings here not only provide insights into the removal mechanism of Hg 0 by MoS 2 , but also facilitate the development of robust MoS 2 -based sorbents to mitigate the harm of industrial flue gases in real-world scenarios.