An experimental study on the structure and surface distribution of hydrophobic nanoparticles stabilized liquid foam

Abstract Nanoparticles (NPs) have been used to enhance the performance of foam in foam flooding process, and their foaming properties have been extensively studied in recent years. The primary aim of this study was to reveal the structure of hydrophobic NPs stabilized foam system, and to understand the distribution of NPs on the liquid film's surface. To achieve this objective, cryo-transmission electron microscope (Cryo-TEM), field emission scanning electron microscope (FESEM) and optical microscope were used to accomplish the observation of both the entire foam system and one single bubble. Meanwhile, the distribution of NPs on the liquid film's surface was analyzed based on the observation results and existence theories. Secondly, the impact of the NPs' concentration on the foam ‘s properties (foaming capacity and foam stability) and the bubbles' sizes were investigated. Besides, the observation results revealed the two-dimensional structure and particle distribution of the NP stabilized foam, and a relationship between the structure and the performance was established based on the investigation on foam's properties. Based on the experimental results, the NPs and surfactants were conjectured to be located at intervals on the surface of the liquid film, meanwhile, the NPs shown significant positive effect on the foam's stability but weak impact on the foaming capacity.