Fuel effects on foams generated using different surfactants

Abstract

Aqueous film-forming foams (AFFF) that contain perfluoro-alkyl substance (PFAS) surfactants are being banned due to their bio-persistence and bio-accumulative behavior. As a result, new surfactants to replace the PFAS-based surfactants are being sought. The focus of this study is to explore the impact of surfactant types on the resistance of fuel transport through the foam. Fuel transport through the foam was measured using static foam ignition tests on a typical hydrocarbon fuel (n-heptane) and an aromatic fuel (trimethylbenzene). The ignition resistance of four different surfactant types as well as AFFF. Experiments in a Dynamic Foam Analyzer were also conducted to relate the ignition resistance to the response of the foam (bubble size, interface structure) at the foam-fuel interface. The shortest ignition times were measured with n-heptane beneath the foam. Foams with the lowest ignition times displayed void formation and a more variable interface compared with the more ignition-resistant foams.