Optimization of the surface performance of environmentally friendly three-phase SiO2 gel foam as an extinguishing agent

Herein, an optimized three-phase SiO2 gel foam specifically designed for firefighting applications with enhanced stability (foam stability ratio = 95.52 %) was developed. The formulation represents a novel approach based on the integration of a multisurfactant system with different foam stabilizers and cross-linking agents, which incorporates seven surfactants from three distinct types (anionic, amphoteric, and nonionic surfactants), significantly improving foaming efficiency and lowering surface tension. Response surface methodology was used to identify the optimal surfactant mixture, thereby providing a systematic and efficient formulation process. The inclusion of sodium alginate and gelatin polysaccharides in the formulation at a 3:7 ratio enhanced the viscosity and stability of the foam. In the formulation, inorganic cross-linking agents CaCl2 and AlCl3 were also introduced at an optimized ratio of 6:4, which further improved foam stability and the overall surface performance. The incorporation of 200–300 mesh silica sand was another key innovation, which improved hydrophilicity, reduced Ostwald ripening, and boosted foam longevity. Comprehensive characterization using X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy validated the robust microstructure and stability of the foam. This study highlights the significant novelty of combining these components and methods to offer a sustainable and efficient firefighting agent with excellent deep penetration capabilities and long-term stability, thus addressing key challenges in firefighting foam development. © 2025 Elsevier B.V.