Inorganic-Organic Antioxidant Gel for Preventing the Spread of Forest Fires

It is easier and cheaper to prevent forest fires than to extinguish them, therefore, the development of long-lasting and environmentally friendly fire-retarding materials is highly desirable to prevent the spread of forest fires. In this study, soluble carboxymethyl starch replaced insoluble carboxymethyl cellulose to improve the compressive strength of inorganic gel and overcome the weakness of fragility. When the concentration of polymer carboxymethyl starch and crosslinking agent aluminum citrate were 0.5% and 0.3%, respectively, the inorganic/organic composite gel showed the best comprehensive performance (including gelation time, water retention, seepage velocity and strength). Additionally, the antioxidant tannin was introduced into the inorganic/organic gel, which effectively inhibited the oxidation of wood flour, making its inhibition rate reached 23.1%, about twice that of pure inorganic gel. This is mainly attributed to the ability of tannin to inhibit the oxidation process of active groups, including carbon-oxygen, hydroxyl, and methyl of the wood powder, thereby enhancing the flame resistance of the composite gel. Probable mechanism of forest fire suppression by the antioxidant composite gel is proposed, which involves oxygen isolation, evaporative cooling, and chain reaction inhibition.