Thermal stability of foams stabilized by fluorocarbon and hydrocarbon surfactants in presence of nanoparticles with different specific surface areas

Mixed dispersions of SiO 2 nanoparticles (NPs) with different specific surface areas (SSAs), nonionic surfactants (APG0810) and fluorocarbon surfactants (FS-50) in water were prepared. The molecular interactions in the APG0810/FS-50/NPs dispersions are characterized. Foam volume decay, foam drainage and coarsening under heat are investigated systematically. Results show that the molecular interactions result in the reduction of surface activity and the increase in viscosity and conductivity with increasing in SSAs. The addition of NPs can effectively inhibit foam decay, foam drainage and coarsening under heat, and enhance the corresponding foam thermal stability of the APG0810/FS-50 solutions. The optimal SSA for NPs enhancing foam thermal stability is 300 m 2 /g. The results can promote the application of NPs in the development of environmentally friendly firefighting foams.