Synergetic adsorption of asphaltenes and oil displacement surfactants on the oil-water interface: Insights on stabilization mechanism of the interfacial film

This research focus on the interfacial stabilization mechanism of the asphaltene-rich oil-in-water emulsions that originated from the alkaline-surfactant-polymer (ASP) flooding produced water. Initially, we investigated the adsorption and aggregation behavior of asphaltenes and oil-displacement surfactants on the oil/water interface through molecular dynamics simulation. The interfacial formation energy for the composite asphaltenes-sodium dodecyl benzene sulfonate (SDBS) interfacial film system was calculated to be −3423.9 kJ/mol, which was much higher than that (−2499.9 kJ/mol) for the monolayer SDBS system. This enhanced interfacial film stability was attributed to the cross-linked aggregation of asphaltenes and SDBS molecules on the oil/water interface. Then, the interfacial properties of various interface systems were also obtained via interfacial adsorption thermodynamics, micromorphology, interfacial tension, and zeta potential analysis to further elucidate the stabilization mechanism. This composite asphaltenes-SDBS interfacial film with its pyknotic structure and high stability resulted in significant technical obstacles for oil-water separation of ASP flooding produced water.