Physical properties and fire extinguishing performance of hydrophobic aluminum hydroxide-ionic liquid-modified dry water powder

In order to improve the poor storage stability and fire-extinguishing performance of dry water powder, this study utilized hydrophobic aluminum hydroxide as the shell additive and ionic liquid as the core additive, and the influence of the composition ratio on its physical properties and fire-extinguishing performance was experimentally investigated. The results show that the dry water containing 22.22 % hydrophobic aluminum hydroxide and 2 % ionic liquid exhibited the best overall performance. The addition of ionic liquid and aluminum hydroxide improved the surface/interfacial properties of the solid shell and the internal liquid, thus increasing the number of hydrogen bonds and the molecular forces between the internal liquids. Additionally, the addition of ionic liquid significantly reduced the evaporation rate of the solution, aluminum hydroxide nanoparticles filled the voids of the dry water shell. These two effects enhanced the pressure resistance and moisture retention of the modified dry water by 46.36 % and 85.69 %, respectively, compared to unmodified dry water. Aluminum hydroxide interrupted the combustion chain reaction by effectively capturing free radicals during combustion. Meanwhile, ionic liquid promoted fire extinguishing through the effects of heat absorption by the imidazolium ring, interruption of the chain reaction, and dissolution of the fuel. With the combined effects, the fire extinguishing efficiency of dry water was improved by 53.49 %. This study provides a novel high-efficiency fire extinguishing material for fire suppression in narrow/obstructed spaces, susceptible to water-stain loss, etc. The