Study of Asphaltene Molecular Structure Effect on Aggregation and Properties of Oil/Water Interface by Molecular Dynamic

It is well known that asphaltene molecules play a significant role in stabilizing the emulsion of water and oil. Molecular dynamics simulation was employed to investigate the aggregation and orientation behaviors of asphaltene molecules in a vacuum, toluene, and water interface. It was found that the simulation results have a good agreement with available data. In order to investigate the effect of asphaltene structures on the self-assembled behavior of them, six different types of asphaltene structures are selected which are different in the terms of molecular weight, carbon-chain size, and heteroatoms in the asphaltene structure. At first, the behavior of asphaltene molecules was studied purely and it was found that the hydrogen bond plays a significant role in asphaltene molecule aggregation. In addition, the interfacial tension results show that the presence of OH and NH groups, as well as hetero atoms in the asphaltene molecules, cause they have hydrogen bonding with water molecules, so the interfacial tension compare to the pure toluene reduces. But on the other hand, if the asphaltene molecules do not have any O and N atoms, they have little tendency to be present at the water surface and they were dispersed inside the toluene solvent.