Modeling of Forced Desorption Processes in a Regenerable Graphene Sorbent for Elemental Mercury Capture

Most sorbents display poor capacity for elemental mercury at elevated temperatures. Graphene is the potential candidate among different high-temperature sorbents. We have studied the physical properties of mercury films on partially hydrogenated imperfect graphene, as well as their heating and bombardment with xenon clusters, by means of molecular dynamics. Hydrogenated edges of a graphene sheet containing Stone–Wales defects withstand heating to 1100 K. Formation of the droplet leads to a decrease in the blunt contact angle. The bombardment of a target with a Xe13 cluster beam at energies of 5–30 eV and incidence angles of 0–60° aiming to remove a mercury film from imperfect graphene has been performed. The graphene is completely cleaned of mercury at a cluster energy of E Xe ≥ 15 eV. Mercury is removed from the graphene film via sputtering of single atoms and droplet detachment. A stress in graphene resulting from forces normal to the sheet plane is noticeably higher than that due to forces acting in its plane. Bombardment at an angle of incidence of 45° is the most efficient and leads to lower graphene roughness. Thus, mercury can be removed from graphene by heating or bombarding with heavy noble gas clusters.