Interaction mechanism of MDH nanoparticles and binary surfactants in foams.

• Molecular interactions exist in the mixture of FS-50/APG-0810/ nano-MDH. • Nano-MDH apparently delay foam drainage and coarsening of FS-50/APG-0810 solutions. • Aggregates formed by nano-MDH//FS-50/APG-0810 in bubble films enhance foam stability. Nanoparticles and surfactants stabilized foams show immense feasibility for development of environmental-friendly firefighting foam. A mixed dispersion composed of magnesium hydroxide nanoparticles (nano-MDH), hydrocarbon surfactant (APG-0810), and fluorocarbon surfactant (FS-50) is used in this study. This work explores the coactions between nano-MDH and surfactants in mixed dispersion and its effect mechanism on foam properties. Results reveal that with increase in nano-MDH content, the conductivity and viscosity of dispersion liquids rise but the surface activity decreases. The initial foam height of APG-0810/FS-50 solution was reduced, foam stability of APG-0810/FS-50 solution was improved as the foam drainage and coarsening were delayed, due to the existence of nanoparticles. Besides, the foam stability, with increasing nano-MDH content, further increases. Foam containing 5% nanoparticles shows optimal performance of potential application in firefighting field considering relatively low viscosity, high foaming ability, and excellent stability. This research can afford important theoretical guidance for developing environmental-friendly fire extinguishment agent based on nano-MDH, and provide support for promoting the advance of fire extinguishing technology. [ABSTRACT FROM AUTHOR]