Study on foam extinguishing agent based on mixed system of branched short-chain fluorocarbon anionic and hydrocarbon cationic surfactants

The traditional aqueous film-forming foam extinguishing agent (AFFF) plays an important role in fighting liquid fires, but its environmental hazard are also increasingly prominent. The key component of conventional AFFF is fluorocarbon surfactant containing perfluorinated C8 segment, which is one of the most refractory organic pollutants in the world. In this paper, a perfluorinated branched short-chain alkyl side chain fluorocarbon anionic surfactant with high surface activity and simple synthesis route was prepared. The surface activity and aggregation behavior of the mixed solution of fluorocarbon and hydrocarbon surfactants were studied by surface tension meter and transmission electron microscope (TEM). When the mixture ratio of fluorocarbon and hydrocarbon surfactant reached 1:10, the addition of cetyltrimethylammonium bromide (CTAB) had little effect on the interfacial adsorption, but could significantly reduce the critical micelle concentration (CMC) of fluorocarbon surfactant. Meanwhile, three kinds of environment-friendly AFFF formulations (F-1, F-2, F-3) were designed with the mixed system of different hydrocarbon surfactants and this fluorocarbon anionic surfactant as foaming agents. The foam properties revealed the F-2 possessed excellent foam performance, the initial foam height h0 was 120 mm, and the 25% drainage time was 240 s, extinguishing time was 30 s, burn-back time was 760 s.