An ultra-sensitive covalent organic framework based smoldering sensor for early warning of a granary fire

Abstract

The rice, as an important strategic material, is stored in the granary every year. Typically, the rice nearly fills the entire granary, making it difficult to detect smoldering in time. Once the smoldering of rice begins, it will be difficult to extinguish. To prevent granary fires, this paper analyzes the pyrolysis products of rice and proposes a novel granary smoldering early warning method based on the color reaction between furfural (the main product during rice smoldering) and aniline hydrochloride, and the excellent gas adsorption performance of three-dimensional covalent organic frameworks (COFs). A small-scale smoldering model of a rice storage granary is built. The smoldering of rice in the small-scale granary is detected successfully by the designed rice smoldering sensor (RSS). The RSS shows good flexibility and ultra-sensitivity for rice smoldering. The minimum monitoring concentration of furfural produced during rice smoldering is 0.03 μg mL⁻¹. The early warning mechanism of the RSS has also been revealed. This work provides a new method for early warning of grain fires.