Abstract: In order to optimize the extinguishing efficiency of traditional foam extinguishing agent, a new type of efficient and environmentally friendly foam extinguishing agent was synthesized from AES, SLES, SDS and BS-12 surfactants. Firstly, foam analysis method and droplet profile analysis method were used to systematically characterize the intermediates and products. Four factors and three levels orthogonal experiments were designed to optimize the ratio and determine the best combination scheme. Then, molecular dynamics simulation was used to study the synergistic effect of their combination. The results indicate that there is a significant synergistic effect between the four surfactant molecules, which significantly enhances the surface activity of the mixed system. The critical micelle concentration (CMC) of the composite system was ultimately measured to be 0.16% using fluorescence spectroscopy experiments. Its surface tension is 28.24 mN/m, and its performance is significantly better than that of a single surfactant. Then add foam stabilizer (xanthan gum, sodium alginate) and cosolvent (urea, propylene glycol, glycerin) to make foam concentrate. Then, the formula was used to prepare fire extinguishing foam using the double syringe technology and tested. The test results showed that the 25% liquid separation time was 274 s, and the viscosity was 25 mm2/s. Finally, the fire extinguishing experiment was conducted in a well ventilated environment, with extinguishing time of only 18 s, which meets the national standard requirements.

Key words: foam extinguishing agent, surfactants, molecular dynamics, surface tension, pyrene fluorescent probe