The properties of asphaltene at the oil-water interface: A molecular dynamics simulation

Abstract

As the major stabilizer for crude oil emulsion in petroleum industry, asphaltene has been concerned more widespread with the increasing demand of energy in the world. The in-depth understanding on its properties at crude oil-water interface has some beneficial effect on dealing with the emulsion in oil industry. To investigate these interfacial properties at molecular level, molecular dynamics (MD) simulation was utilized. The results show that asphaltene molecules tend to different orientation between them at this interface so as to decrease the repulsive force of aggregation process. Moreover, the contributors to asphaltene stability at crude oil-water interface also were discussed. It mainly includes hydrogen bond networks around asphaltene polar group. The hydrogen bond networks behave like an anchor to grab hold of asphaltene at the interface. The aggregation properties of asphaltene at oil-water interface were obtained by using the umbrella sampling method. The results indicate that aggregation state is most stable for asphaltene molecules at oil-water interface and the system free energy will increase after the aggregate be broken.