Adsorption of polycyclic aromatic hydrocarbons on graphite surfaces

Polycyclic aromatic hydrocarbons (PAHs) are emitted into the atmosphere as byproducts from combustion. Once emitted into the atmosphere, PAHs either can exist in the gas phase or they can be adsorbed onto particle surfaces, such as soot and charcoal. PAHs are one of the most widespread pollutants and are known carcinogens, mutagens and teratologies for humans. Unfortunately, they are easily inhaled when absorbed on the surfaces of airborne soot particles produced by the incomplete combustion of carbonaceous fuels. Studying the mechanism of adsorption of PAHs onto soot surfaces is therefore an important problem. In this work, we chose coronene (C24H12) to model the interaction between a typical PAH and a graphite surface. We comment that using conventional computational methods, such as full ab initio, is usually not feasible owing to the large molecules involved. Accordingly, we adopt an applied mathematical modelling approach and we therefore exploit the continuous atomistic approximation together with the Lennard–Jones potential in order to investigate this problem. The major result of this study is an analytical expression for the interaction energy which we then use to describe the mechanism of adsorption of a coronene molecule on a graphite surface.