Drainage of aqueous film-forming foam stabilized by different foam stabilizers

The present study focuses on the drainage property of aqueous film-forming foam stabilized by different types and concentrations of foam stabilizers. Aqueous film-forming foam (AFFF) formulation concentrates are prepared based on the main components of fluorocarbon surfactant, hydrocarbon surfactant, and organic solvents. Carboxymethylcellulose sodium (CS), xanthan gum (XG), and lauryl alcohol (LA) are selected as foam stabilizers of the AFFF. Surface tension, viscosity, and foamability tests of the AFFF solutions are conducted to evaluate the effect of foam stabilizers on the properties of AFFF solutions. Particularly, an apparatus is established based on the law of connected vessel in order to obtain the instantaneous mass of liquids drained from foams. The drainage features of the AFFFs containing different foam stabilizers are analyzed and compared with each other. The results indicate that AFFF drainage is significantly affected by the type and the concentration of foam stabilizers. The addition of CS and XG to AFFF results in a deceleration of foam drainage, while foam drainage is accelerated by the addition of LA. The variations of surface tension, viscosity, and liquid fraction of foams are the main reasons for the varying foam drainage rate. This study provides a direct connection between chemical components and fundamental properties of AFFF.