Interfacial behavior and interaction mechanism of pentol/water interface stabilized with asphaltenes

Emulsions stabilized with asphaltenes are undesirable in oil production due to the challenges associated with fouling, corrosion and environment contaminations. To understand the stabilization mechanism, the interfacial behavior and interaction mechanism of pentol/water interface in the presence of asphaltenes were investigated by interfacial tension (IFT) and atomic force microscopy (AFM) force measurements. The measured IFT increases as NaCl concentration increases from 0 to 3 M, and decreases as asphaltenes concentration increases from 50 to 1000 ppm. The drop probe AFM force measurements between two water droplets in pentol with interfacial asphaltenes show attraction during approach attributed to the solvophobic interaction. During retraction, interfacial adhesion F_adh/R is measured arising from the contact and interpenetration or local aggregation of asphaltenes molecules. F_adh/R gradually decreases with the increase of NaCl concentration, originated from the enhanced steric repulsion due to the accumulation of more asphaltenes at pentol/water interface with addition of salts. With increasing asphaltenes concentration, F_adh/R keeps decreasing due to the self-aggregation of large amounts of asphaltenes molecules at the interface. This work provides useful information on the stabilization mechanism of pentol/water interface with adsorbed asphaltenes, with implications for developing effective technologies or products to solve the challenging emulsion issues.