Investigations on oil detachment from rough surfaces in an aqueous solution

Herein, detachment of oil molecules from perfect and defective aluminum oxide surfaces in an aqueous solution was investigated using atomistic molecular dynamics simulations. On the basis of the α-Al2O3 (0001) plane, three types of surface defects, pits, grooves, and protrusions, were created and applied to explore the effects of surface defects on the detachment of oil molecules in an aqueous solution. Our simulation results indicate that the surface defects with various topographies affected the oil detachment to different degrees. The adsorption conformation of oil molecules on each defective alumina surface evidently changed during the entire simulation. The effect of each type of surface defect on oil detachment follows the order grooves < pits < protrusions. After this, the oil-alumina and water-alumina interactions were investigated to determine the effects of the surface defects on the driving forces responsible for the conformational change of oil molecules on each type of defective alumina surface. The microscopic conformational changes and detachment of oil molecules from the defective alumina surface discussed herein are believed to be helpful to enrich the mechanism of oil detachment from a rough substrate surface