No abstract

An eco-friendly and bio-based ternary hybrid hydrogel consisting of carrageenan, vermiculite, and dimethyl methyl phosphate (DMMP) was prepared through a facile one-pot method. Rheological tests showed that this ternary hybrid hydrogel was a power-law fluid. The formulation of the ternary hybrid hydrogel was also screened, and the optimal formulation was found to be the ternary hybrid hydrogel containing 1 wt% carrageenan, 2 wt% DMMP, and 4 wt% vermiculite. Firefighting experiments showed that the ternary hybrid hydrogel could stop the chain reaction and rapidly reduce the temperature of combustion. Compared to water, the extinguishing time of the ternary hybrid hydrogel was shortened by 46.6%, and the volume consumed was reduced by 43.3%. The superior fire extinguishing efficiency of the ternary hybrid hydrogel could be attributed to the combined effect of each component: carrageenan provides viscosity, making the hydrogel firmly cover the burning surface; DMMP works as a free radical scavenger that can stop chain reactions; and vermiculite acts as a barrier layer, which helps to insulate air and heat and prevent resurgence. This work provides an environmentally-friendly, cost-effective, and bio-based hybrid hydrogel for firefighting.

An eco-friendly and bio-based ternary hybrid gel consisting of alginate, sepiolite, and ammonium polyphosphate (APP) was fabricated via a facile one-pot method. Rheological tests showed that this ternary hybrid hydrogel exhibited shear-thinning behavior. Firefighting experiments showed that a burning cotton bale extinguished by using water re-ignited, whereas the ternary hybrid gel effectively prevented smoldering and re-ignition of the cotton bale because of the firm adhesion of the hybrid gel to the surface of the cotton bale. Firefighting experiments also showed that the hybrid gel only covered the upper layer of a rice pile after firefighting efforts, whereas water ruined the grains completely, making them inedible and suitable for use only as a feed or for discard with the burnt grains. The firefighting mechanism of this hybrid gel involved multiple modes of action: volatilization of the large amount of water in the gel absorbed much heat (cooling the combustion zone), APP decomposed into non-flammable ammonia when heated (dilution of flammable volatiles and oxygen), and APP and sepiolite were conducive to forming a continuous and dense char layer (insulation of the exchange of combustible gas, heat, and oxygen). This work provides an environmentally friendly, cost-effective, and bio-based hybrid gel for firefighting in grain and cotton reserves.