The project team plans to advance the innovative concept of using metal carbonate nano-encapsulated ionic liquid (NEIL) surfactant formulations for use in fire-suppression operations. In this project, WP18-1597, the project team investigated an alternative out-of-the-box pathway to extinguish large fires, which is not an AFFF mimic. The project team aims to develop this concept further and test the next generation of firefighting foam formulations containing a mixture of metal carbonate NEIL and a long chain surface active ionic liquid (IL) as surfactants. The preliminary investigation has demonstrated that spreading coefficient of an IL surfactant solution can be positive or even as high as 3 millinewtons/meter (a key MIL-F-24385F requirement), making it a suitable candidate for firefighting applications. The present endeavor is a full scope work to develop and test a fluorine-free NEIL fire-extinguishing foam. The objective is to address SERDP’s goal to develop a sustainable ‘PFAS-free’ firefighting formulation that meets current environmental requirements and have equivalent or better performance to fluorinated Aqueous Film Forming Foam (AFFF).

The project team will provide an alternative pathway to extinguish hydrocarbon fires using metal carbonate NEILs and a long chain surface-active ILs and additives as surfactants. The proposed formulation will provide various physical and chemical barriers to fire suppression in addition to favorable thermodynamic/kinetic conditions to generate cooling characteristics necessary for fire extinguishment that mimics AFFF firefighting performance. The proposed formulation will provide aqueous film-forming foam that extinguishes fires by 1) fire heat absorption and an endothermic reaction (MgCO3→MgO + CO2, ΔH° 118 kJ/mol), 2) generation of a CO2 blanket that smothers the fire via oxygen deprivation, 3) creation of a sealing barrier to diffuse flammable vapors, 4) furnishing a kinetic barrier and a less energetic pathway to IL vaporization, 5) an increase in foam stability by delaying the coalescence of bubbles, and 6) exploitation of the IL self-healing properties. The formulation has the potential to exceed the performance of current AFFFs as it provides additional, unique and effective pathways to extinguish large fires.

AFFF is the most effective fire-suppressant that brings rapidly under control and extinguishes hydrocarbon fires. AFFF formulations that rely on perfluoroalkyl sulfonates have high enthalpies of vaporization and degradation as well as unique film-forming capabilities, which make them ideal fire suppressants. However, perfluorinated compounds pose serious environmental risks due to their toxicity and persistence in the environment. A variety of fluorine-free (FF) or per and poly fluorinated alkyl substance (PFAS)-free firefighting foam formulations have been developed to replace the AFFF formulation. However, none match the AFFF firefighting performance. The innovative concept of NEIL-based agents provides an alternative pathway to extinguish hydrocarbon fires. The formulations will provide various physical and chemical fire suppression barriers, which will allow the project team to match AFFF firefighting performance. They will show the application of the formulation to extinguish Jet Propellant 8 jet fuel fires.