Co-adsorption behavior of aggregated asphaltenes and silica nanoparticles at oil/water interface and its effect on emulsion stability

In petroleum industry, crude oil emulsions are commonly formed in oilfields. The asphaltenes and fine particles in crude oil may affect the stability of the emulsions by adsorbing at the water/oil interface. In this research, the effect of silica nanoparticles and asphaltenes on emulsion stability is explored first. The asphaltenes are proved to benefit emulsion stability. Unlike the asphaltenes, however, the modified silica nanoparticles may have positive or negative effect on emulsion stability, depending on the asphaltene concentration and aggregation degree in the emulsions. Further, it is confirmed by conducting interfacial experiment that the asphaltenes and particles can adsorb at the interface simultaneously and determine the properties of the interfacial layer. More in-depth experiments concerning contact angle and asphaltene adsorption amount on the particles indicate that the asphaltenes can modify the wettability of the particles. Higher concentration and lower aggregation degree of the asphaltenes can increase their adsorption amount on the surface of particles and then improve the modification effectiveness of the particles. Resultantly, the particles with good modification effectiveness can enhance the emulsion stability while the particles with poor modification effectiveness will weaken the emulsion stability. (C) 2022 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.

Automated summary

In the petroleum industry, the stability of crude oil emulsions is affected by the presence of asphaltenes and fine particles at the water/oil interface. This study explores the impact of silica nanoparticles and asphaltenes on emulsion stability. It is found that asphaltenes contribute to emulsion stability, while the effect of modified silica nanoparticles can be positive or negative depending on the asphaltene concentration and aggregation degree. Experimental results confirm that asphaltenes and particles can adsorb at the interface simultaneously, with asphaltenes modifying the wettability of particles. Higher asphaltene concentration and lower aggregation degree lead to increased adsorption and improved modification effectiveness of the particles, ultimately enhancing emulsion stability.