Molecular Dynamics Study On Removal Of Aromatic Hydrocarbon Contaminants By Graphene

Polycyclic aromatic hydrocarbons(PAHs) are well-known for their mutagenic, carcinogenic and teratogenic effects. And many rivers, including the Yellow River, Minjiang River, Xiamen Port, have been polluted by PAHs. So it’s imminent to effectively remove PAHs from polluted rivers. Though there are many ways based on different theories, physical adsorption plays a significant role in dealing with PAHs. And graphene is a common nanomaterial, whose high surface-to-volume ratio and long distance π-conjugated structure characterize a huge adsorption potential.In this thesis, we used nano-carbon material to adsorb PAHs by Molecular Dynamics. And natural organic matter(NOM) is ubiquitous in the natural environment, so it’s necessary to account for the influence of NOM. This work was to characterize the adsorption capacity of naphthalene(NPH) on the surface of graphene in water containing n-butyl alcohol and palmic acid as NOM.Results indicate that graphene can effectively adsorb NPH, more than 80% of the NPH can be adsorbed on the graphene’s surface; when there was a gas-liquid interface, NPH was mainly adsorbed to the graphene or floated on the interface of the gas-liquid, with little fraction free in the aqueous phase. This phenomenon gives us an idea that disposal of the water’s surface can remove much of PAHs. In the presence of NOM: at low concentration range, NOM may coat the graphene and increase the adsorption capacity for NPH, since NOM’s hydrophilic property can increase the stability of graphene in water; at higher concentration range, NOM and NPH competed for sorption sites and the majority of the graphene surface was covered with NOM reducing the graphene’s adsorption capacity for NPH.