Interfacial designing of firefighting foams: Unveiling the molecular synergy for enhanced fluid stability and corrosion mitigation

The prolonged contact of firefighting foams (e.g., Fluoroprotein foam, FP) with metallic components in fire suppression systems can cause severe corrosion, leading to equipment degradation, increased maintenance costs, and potential operational failure. To mitigate this problem, a low-corrosion FP formulation is developed via molecular synergistic design. The combination of nonionic surfactant alkyl polyglucoside with short-chain fluorocarbon surfactant, along with an optimized ternary corrosion inhibitor system (sodium gluconate-potassium sorbate-benzotriazole), enabled simultaneous enhancement of surface activity and corrosion inhibition. These results show that the developed system significantly reduces surface tension (∼7.32 mN/m lower than commercial FP) while decreasing the corrosion rates of Q235 galvanized steel and 1060 aluminum alloy by 62% and 48%, respectively, along with a notable reduction in corrosion current density. In terms of foam performance, the system exhibits improved foaming ability, foam stability, and retarded drainage. Extinguishing tests further demonstrate a reduction in extinction time by about 4 s compared to commercial FP. This study indicates that rational surfactant-inhibitor synergy design can significantly enhance the metal compatibility of FP while maintaining fire extinguishing performance, offering a feasible strategy for developing low-corrosion FP extinguishing agents.