A comprehensive exploration of mercury adsorption sites on the carbonaceous surface: A DFT study

•Twelve different kinds of defective carbonaceous surfaces were researched systematically.•The real adsorption sites of Hg0 on the unburned carbon in fly ash.•The defective carbon surface exceptional adsorption performance.•The influence of oxygen functional groups on Hg0 adsorption. Mercury polluti...

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Bibliographic Details
Published in:Fuel (Guildford) 2020-12, Vol.282, p.118781, Article 118781
Main Authors: Yan, Ge, Gao, Zhengyang, Zhao, Mingliang, Yang, Weijie, Ding, Xunlei
Format: Article
Language:English
Subjects:
Adsorbents
Adsorption
Adsorption mechanism
Adsorption sites
Bioaccumulation
Carbon
Chemisorption
Coal-fired power plants
Defective carbonaceous
Density functional theory
Electric power generation
Electron density
Fly ash
Functional groups
Localization
Mercury
Mercury (metal)
Mercury surface
Power plants
Surface chemistry
Surface defects
Toxicity
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Summary:•Twelve different kinds of defective carbonaceous surfaces were researched systematically.•The real adsorption sites of Hg0 on the unburned carbon in fly ash.•The defective carbon surface exceptional adsorption performance.•The influence of oxygen functional groups on Hg0 adsorption. Mercury pollution released from coal-fired power plants has caused worldwide concern for its toxicity, global range transportation, and bioaccumulation. Unburned carbon in fly ash is considered to be a promising adsorbent to effectively remove elemental mercury. However, the active sites of the unburned carbon for Hg0 adsorption have not been clearly identified, which greatly hinders the development of effective adsorbents. To reveal the adsorption sites of the carbonaceous surface, the adsorption process of Hg0 on different carbonaceous surfaces was systematically investigated through density functional theory. The Mayer bond order, Electron localization function, and Electron density difference were used to analyze the adsorption mechanism of Hg0. Meanwhile, the oxygen-containing functional groups were also considered to research the influence on mercury adsorption with the defective surface. The adsorption of Hg0 on defective carbonaceous surfaces is associated with stable chemisorption, and surface defects can significantly improve the adsorption energy of Hg0. This theoretical study provides theoretical guidance for the development of mercury removal technology with carbon materials in the coal-fired power plant.
ISSN:0016-2361
1873-7153
DOI:10.1016/j.fuel.2020.118781