Multiscale Investigation of Effect of Nanoparticles as Foam Stabilizer: From bubble to Bulk Scale

Understanding foam (gas dispersion in liquid phase) dynamics and stability is crucial to many industrial applications such as drug delivery and CO₂ geological sequestration. Foam is highly susceptible to destabilization owing to rapid liquid drainage, gas diffusion, and bubble coalescence. This study evaluates the synergistic effect of nanoparticles (NPs) and surfactant combinations for enhancing the mechanical strength of bobbles and the foam stability at bulk scale. Various types of NPs of different surface groups and geometry (such as silica with different surface groups, graphene oxide nanoplatelets, short-length carbon nanotubes, and iron oxide nanorods) were evaluated in synthetic seawater and high temperatures for their ability to improve the foam stability. Bulk testing involved measuring foam volume, half-life, drainage rate, and bubble size distribution under controlled conditions to assess the performance of each nanoparticle-surfactant combination. Light microscopy and image processing techniques were also used to study bubble dynamics and foam coarsening in a quasi-2D setup. The results show that NPs significantly improved the foam stability by reducing drainage and bubble coalescence. The presence of NPs was found to slow the rate of bubble growth and coarsening attributed to the formation of a robust network within the foam lamellae, however excessive NPs concentrations negatively impact foam properties that can lead to aggregation. These findings suggest that NPs effectively enhance foam stability by reinforcing the foam structure at macroscopic and microscopic levels. The results also show that optimal concentration of surfactant and NPs is crucial for achieving maximum foam stability.