A facile sunflower pectin gel foam for liquid fuel fire suppression with ReaxFF characterisation on its char-enhancing ability

A biomass fire suppression gel foam (FSGF) with outstanding thermal stability and fire resistance performance was synthesised to improve the flame retardancy of foam agents on liquid fuel fires. The foam comprehensive index, microstructure, thermal stability, fire resistance and extinguishing properties of the FSGF were benchmarked against aqueous film-forming foam (AFFF). Subsequently, reactive forcefield (ReaxFF) molecular dynamics (MD) simulations were performed on the FSGF to study the thermokinetic properties. Based on the experimental results, a porosity layer was found on the external film of FSGF, which enhanced the thermal stability of the foam. The gelling mechanism of the foam is the formation of an O–Ca–O bond. Through MD simulations it was discovered that the remained calcium oxide/hydroxide species when deposited on fuel surfaces would promote char formation as they capture H/O atoms via dehydration. Alternatively, the foam showed better thermal stability than that of AFFF due to a lower weight loss rate and longer collapse time. The extinguishing performance tests demonstrated that the fire extinguishing time and resistance time of FSGF respectively are 72 s and 801 s, showing a significant potential to suppress the re-ignition of tank fires.