Gastric Mucus-Inspired Oxygen-Blocking Inhibitor: Mechanisms and Performance in Coal Spontaneous Combustion

Coal spontaneous combustion (CSC) poses a critical hazard in coal production safety, demanding advanced prevention technologies. Inhibitors offer an effective fire suppression approach, yet conventional water-soluble variants require frequent re-spraying. To address this limitation, the paper developed an inhibitor based on multi-barrier oxygen shielding mechanisms that simultaneously maintain suppression efficiency and inhibit coal-oxygen recombination. Inspired by the multi-protective barrier system of gastric mucus, we engineered a composite inhibitor (termed Gastric mucus-inspired acidified anti-permeability deoxygenation inhibitor, GMA) with synergistic acidification, anti-permeability, and chemical deoxygenation functionalities, systematically characterizing its physicochemical properties. Based on oxygen consumption experiments, the optimal component ratios in the inhibitor are determined: C₆H₁₂O₆ (2.5 wt%), DL-malic acid (0.004 wt%), Sodium alginate (2 wt%), MgCl₂ (0.225 wt%), and a mass ratio of C₆H₁₂O₆ to Glucose oxidase is 100:1. Additionally, experimental results demonstrated that GMA maintains its inhibitory efficacy under low-temperature conditions, and the inhibition effectiveness positively correlates with the thickness of the barrier layer. Utilizing quantum chemical theory, analyses of molecular surface electrostatic potential, Fukui functions, and chemical softness revealed that Mg²⁺ enhances electron transfer in reduced flavin adenine dinucleotide (FADH₂), increasing its reactivity. Furthermore, an investigation of intermolecular interactions in the FAD₂-O₂ hybrid system revealed that its binding energy surpasses that of most oxygen-containing functional groups in coal. Strong hydrogen bonding and electron transfer are the main interactions, supplemented by weaker hydrogen bonds and van der Waals forces. This paper establishes a multi-barrier oxygen-shielding inhibition system based on bionic principles, providing a novel framework for advanced inhibitor development.