Properties of Foams Stabilized by Silica Nanoparticles and Surfactants Under Typical Liquid Fuels

Nanoparticles have been extensively studied in firefighting foam applications. However, the effects of typical fuel types on nanoparticle‐stabilized foam performance remain unclear. This study investigated how three fuels (n‐heptane, kerosene, diesel) affect the properties of foams containing silica nanoparticles, short‐chain fluorocarbon surfactant (FS‐50), and nonionic hydrocarbon surfactant (APG‐0810). Fuel presence increased dispersion viscosity (diesel > kerosene > heptane) and reduced foamability. Nanoparticle addition decreased absolute zeta potential in fuel‐containing systems while increasing it in oil‐free systems. Heptane reduced particle size but increased polydispersity; diesel caused the largest particle size increase. Diesel exhibited the poorest foam stability due to viscosity enhancement. Nanoparticle incorporation retarded drainage and decay, enhanced viscoelasticity (increasing G′ and G″), and prolonged liquid film lifetime through network structures at Plateau borders. Fuel presence accelerated foam drainage and reduced film stability. Heptane demonstrated superior oil resistance, whereas diesel exhibited the poorest performance (thinning index: −0.5 to −0.9). This study provides guidance for developing efficient firefighting foams targeting liquid fuels.