Aggregation behavior and foam properties of the mixture of hydrocarbon and fluorocarbon surfactants with addition of nanoparticles

Aqueous foam is widely used in many industrial fields. Study on foam properties is the key to reducing additive amount of foaming agents and stabilizers as well as the economic cost, and improving utilization efficiency of foam products. The molecular aggregation behavior, foaming ability, foam drainage, and foam coarsening of the mixtures of hydrophilic silica nanoparticle (NP), anionic hydrocarbon surfactant (SDS), and amphoteric fluorocarbon surfactant (FS-50) were studied systematically. Results indicated that the addition of NP slightly affected the molecular aggregation behavior of the mixed solutions of SDS/FS-50. The surface activity, dynamic viscosity, and foaming ability of the foam dispersions increased slightly with increasing NP concentration. The conductivity of the dispersions decreased slightly with increasing NP concentration. Foam stability was significantly affected by NP concentration. When the NP concentration is lower than 1%, the addition of NPs accelerated foam drainage and coarsening. When the NP concentration is higher than 1%, the addition of NPs decelerated foam drainage and foam coarsening and thus reduced foam stability. The foam stability of SDS/FS-50 solutions was further enhanced with increasing NP concentration. This study provides a basis for the application of foams stabilized by NPs in fire extinguishing agents.