Modeling the conformational change of oil contaminants on Al₂O₃ surface in aqueous solution: the effect of molecular weight

A molecular dynamics simulation study was performed to investigate the influence of molecular weight (MW) on the conformation dynamics of oil contaminants onto Al₂O₃ surface in aqueous solution. In the present work, two kinds of adsorption contents were used for each kind of oil contaminants. The simulation results reveal the apparent effect of MW on the dynamics of oil contaminants. Ignoring different adsorption contents, oil contaminants undergo similar microscopic conformational change processes. Meanwhile, some new features are exhibited, owing to the effect of different MWs and oil adsorption contents. At low adsorption content, the oil contaminants with high-MW finally form a contact angle with the hydration substrate surface, while those with low-MW are thoroughly detached. As for oil contaminants at high adsorption content, most of them could not be thoroughly detached from Al₂O₃ surface. Further, steered molecular dynamics (SMD) simulations were carried out to investigate the microscopic detachment of residual oil contaminants under the action of external force. Finally, the effect of temperature on the conformational change of oil contaminants was studied from molecular scale and it was found that the increase of temperature could effectively promote the detachment of oil contaminants, despite of the influence of MW. All findings in the present study are believed to be helpful for the understanding of the removal mechanism of oil contaminants on solid surface.