Study on the adsorption characteristics of organic contaminants on alumina surface coated with clean graphene and the influence of amorphous carbon on wetting behavior

This paper investigates the adsorption performance of clean graphene coated on an alumina (Al2O3) substrate towards two common industrial organic contaminants, dibutyl phthalate (DBP), and n-dodecane. The adsorption effects were examined through contact angle measurements. We have observed that the alumina exhibits enhanced adsorption capacity for both organic contaminants, DBP and n-dodecane, after being coated with clean graphene. The presence of graphene significantly enhances the polar component of the surface free energy of alumina, resulting in the extraordinary attraction of the substrate towards the liquids with highly polar components in surface tension. In our experiments, we observed that although graphene was not contaminated by hydrocarbons in the air, the presence of amorphous carbon on its surface still had an impact on the wettability of the substrate. Molecular dynamics simulations are utilized to explore the adsorption behavior of the two organic contaminants on graphene with varying degrees of amorphous carbon present on its surface. The presence of amorphous carbon also reduces the adhesion energy and desorption free energy between organic contaminants and the substrate, weakening the interaction between the liquid and the substrate and increasing the risk of spontaneous desorption. These findings lay the foundation for graphene-based alumina materials in the field of adsorption of organic contaminants.