Fluorosurfactant retention in the foam blanket during gravitational drainage of an aqueous film-forming foam

A model aqueous film-forming foam (AFFF) comprising a fluorocarbon surfactant (6:2 FTSaB), hydrocarbon surfactant, solvent, and water was deployed on heptane fire with the gravimetrically-drained solution collected at regular time intervals analysed for concentration. Foam drainage behaviour within system non-linear both control (no exposure) fire-exposed tests, as would be expected. However, concentration of fluorosurfactant initially lower, increasing time. This suggests that fluorosurfactants are retained blanket longer than other constituents foam. is proposed to result from unequal probability rupture in bubbles blanket: rate collapse decreases time, lower stability burst until those higher persistence content remain.