Effect of asphaltene structure characteristics on asphaltene accumulation at oil-water interface: An MD simulation study

Abstract

Asphaltenes possess the ability to accumulate at the interface of oil and water, leading to the formation of stable emulsions. These emulsions pose significant challenges in oil transportation and processing. In order to investigate the impact of asphaltene structure on the stability of the oil-water interface, various models were created using molecular dynamics simulations. These models involved modifications in the number of aromatic rings and types of oxygen-containing functional groups present in the asphaltenes. To support the findings, several analyses, such as radial distribution function, binding energies, and interface formation energy, were conducted. The simulation results indicate that an increase in the number of aromatic rings in the asphaltenes significantly enhances the binding energy at the emulsion interface, from − 215 kcal/mol to − 383 kcal/mol. This increased binding energy greatly improves the stability of the interface. Furthermore, altering the types of oxygen-containing functional groups and binding sites results in a change in the interface binding energy from − 381 kcal/mol to − 526 kcal/mol. The oxygen-containing functional groups of the asphaltene side chain vertically enter the water, forming a crosslinked structure. The polarity of these functional groups can influence the strength of the crosslinked structure, thereby impacting the stability of the interface. This paper establishes the relationship between changes in asphaltene structure and the aggregation state and energy of the interface, offering theoretical insights for future research on new demulsifiers.