565 / 2019-01-16 14:43:00

Theoretical studies of hydrocarbon functional groups on elemental mercury adsorption on carbonaceous surface

DFT、elemental mercury、hydrocarbon functional group、carbonaceous surface、adsorption

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Hydrocarbon functional groups are one of the most common functional groups on the activated carbon surface, but there are significant differences for activated carbon with different hydrocarbon functional groups on adsorption of elemental mercury. In this paper, the effect of hydrocarbon functional groups on elemental mercury adsorption on a carbonaceous surface is investigated by density functional calculations. The carbonaceous surface is represented by a cluster model consisting of a nine-fused benzene ring. The carbon atoms on the upper side remain unsaturated to provide active sites for the reaction. 17 possible approaches in which hydrocarbon functional groups are adsorbed on the carbonaceous surface are conducted. After geometric optimization, there are 11 models are selected as objects of study. The results indicate that the hydrogen atoms on the functional groups may escape and form a covalent bond with carbon atom on the carbonaceous surface. Such phenomena results from the unstable adsorption for hydrocarbon functional groups. In addition, the carbon atoms on the functional groups may be contected with carbon atoms on the carbonaceous surface to form a new carboatomic ring, which can enhance the adsorption of the functional groups. In most models, the adsorption of hydrocarbon functional groups can increase the carbon-carbon bond length on both sides of the adsorption site, result in the electric transfer from adsorption site to both sides and increase the activity of its neighboring carbon atoms. The adsorption of mercury is not only related to the carbon atoms on the carbonaceous surface, but also those on the hydrocarbon function groups. When the mercury atom doesn’t bind with the carbon atom on the functional groups, the adsorption is affected by the carbon atoms on the carbonaceous surface. On the contrary, when the mercury atom binds with the carbon atom on the functional groups, the adsorption is affected by the common effect of the carbon atoms on the carbonaceous surface and the carbon atoms on the functional groups.