ORIGINAL RESEARCH article
Front. Chem.
Sec. Green and Sustainable Chemistry
Reducing Spontaneous Combustion Propensity of Lignite through Functional Group Regulation by Microbial Flame Retardant
Provisionally accepted
- 1Hulunbuir University, Hulun Buir, China
- 2Hulunbuir College Mechanical Engineering Collaborative Innovation Research Center, Hulunbuir, China
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This study investigated the effects of microbial treatment on lignite functional group structure and thermal oxidation characteristics using Pseudomonas putida (CICC21884) through Fourier transform infrared spectroscopy (FTIR), thermogravimetric-differential scanning calorimetry (TG-DTG-DSC), spontaneous combustion propensity testing, and enzymatic activity assays. After 72 hours of treatment, initial weight loss temperature increased from 140.99°C to 162.12°C (+21.13°C), maximum weight loss rate decreased from 1.6%/min to 0.74%/min (-53.75%), and ignition temperature increased from 270.34°C to 294.29°C (+23.95°C). Oxygen-containing functional groups decreased from 41% to 36%, aromatic groups increased from 17% to 30%, and hydroxyl content decreased from 39% to 31%. The spontaneous combustion propensity index peaked at 540.15 after 24 hours (+28.71% vs raw coal). Three extracellular enzymes—aromatic acid monooxygenase (22.0 U/mL), esterase (68.5 U/mL), and catalase (125.5 U/mg protein)—peaked at 24 hours, showing temporal correlation with functional group modifications. Linear regression analysis across seven treatment conditions revealed general trends between functional group composition and thermal stability parameters, with weak to moderate correlations (R²=0.11-0.26) influenced by limited sample size and outlier effects. This study suggests that Pseudomonas putida may degrade the oxygen-containing functional groups and promote coal aromatization, thereby inhibiting the low-temperature oxidation process of lignite and potentially providing an environmentally friendly biotechnological approach for lignite spontaneous combustion prevention.
Keywords: functional groups, lignite spontaneous combustion, microbial flame retardant, Pseudomonas putida, spontaneous combustion propensity, thermogravimetric analysis
Received: 05 Jan 2026; Accepted: 28 Jan 2026.
Copyright: © 2026 Ge, Qin, Wang and Song. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Liyuan Qin
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