Novel silica hydrogel-based forest fire extinguishing agent: Construction, fire extinguishing performance and mechanism study

The frequent occurrence of forest fires has caused a great threat to the ecological environment and the safety of human life and property. How to effectively prevent and control forest fires has become a top priority. However, water-based fire extinguishing agents commonly used in forest fires possessed the problems of poor spraying effectiveness, adhesion and spreading, and fire extinguishing efficiency. Inspired by the porous thermal insulation materials, a novel silica hydrogel-based fire extinguishing agent (SiKP) was successfully prepared by micro-crosslinking silica aerogel and introducing phosphorus and potassium fire extinguishing elements. SiKP showed excellent high-temperature adhesion properties on wood surfaces and their pH meets the requirements of its application. After spraying SiKP, the open flame of the wood stacks was extinguished quickly within 2 s and the smoldering time of wood stacks was 29.71% less than that of pure water. The phosphorus- and potassiumcontaining free radicals and inert gases from the decomposition of SiKP effectively interrupted the free radical chain reaction and diluted the combustible gas concentration in gas phase. Besides, SiKP promoted the dehydration and charring of forest vegetation and the formation of a compact barrier char layer effectively prevents the transfer of heat and flammable volatiles in condensed phase. Consequently, the total heat and total smoke release of NW/Si3K3P6 were decreased by 51.05% and 72.86% compared with pure pine. This novel forest fire extinguishing agent with excellent adhesion, fire extinguishing, and sustained fire resistance properties shows great value for the prevention and control of forest fires.