The objective of this limited scope effort was to develop non-fluorinated, biodegradable bio-derived film-forming composite formulations based on parts of plantain instead of toxic and bio-persistent polyfluorinated firefighting foams. The aim was to develop firefighting products that meet the performance requirements specified in military specification (MIL-SPEC) MIL-F-24385F, while being environmentally compatible and non-toxic.
Plantains are natural products that are inherently resistant to fire. Various parts of the plantain, including fibers, stems, leaves, and banana peels, are fire-resistant and completely biodegradable. Plantain sap has been reported to contain various glycosides and dopamine, both of which has been reported to act as a flame retardant. In this project, plantain sap and cellulose derived from banana peels were mixed in various ratios with siloxane and hydrocarbon surfactants in fluorine-free firefighting foam formulations and were tested for surface tension, foam formation, stability, and gasoline pool firefighting efficiency.
The banana sap containing a mixture of organic chemicals did not exhibit pool fire quenching properties. The banana peel powders contained potassium as the major inorganic content and, as such, did not contribute to the firefighting. Water-soluble cellulose derived from banana peel powder was tested as a foam stabilizing additive to siloxane and hydrocarbon surfactants in the per- and polyfluoroalkyl substances (PFAS)-free firefighting foam formulations. The banana peel-derived cellulose demonstrated lower viscosity than commercial polysaccharide additives and excellent firefighting capability when mixed with conventional surfactants. The banana-cellulose mixed surfactant formulations could potentially replace PFAS-containing aqueous film-forming foam (AFFF) formulations with scaled-up production of banana-cellulose powders and optimization of the PFAS-free formulations with the goal of meeting the MIL-SPEC standard.
PFAS-free firefighting foams have considerable financial, socio-economic, public health, and environmental advantages over bio-persistent and toxic AFFF products. The new formulations based on plantains developed in this effort are compatible with environmental regulations, while having the potential to meet the MIL-SPEC standard. This limited scope effort has demonstrated that readily biodegradable natural products could be used in the firefighting formulations if modified into a water-miscible form. The natural product-based formulations can result in developing PFAS-free Class B foams to fight against liquid fuels with additional research and formulation optimization. (Project Completion - 2022)