Study on the pore structure and CO2 adsorption characteristics of Wudong low-rank coal under the action of bacteria

Injecting CO₂ into the goaf for storage can not only reduce CO₂ emissions, but also prevent the spontaneous combustion of residual coal in the goaf. This article intends to utilize the degradation effect of bacteria to promote the development of the pore structure of Wudong coal and improve the adsorption capacity for CO₂. Four bacteria, namely P. huatugouensis, S. polyaromaticivorans, P. putida and B. subtilis, were selected to degrade Wudong coal. The effects of slurry density, inoculation volume, incubation temperature and degradation time on the degradation effect were explored. The changes in the chemical structure of Wudong coal before and after degradation were analyzed using FTIR and XRD. The dissolution products of Wudong coal degraded by four bacteria were characterized by GC-MS. And it was found that the four bacteria mainly act on the oxygen-containing functional groups and branched fatty hydrocarbons of Wudong coal, resulting in a decrease in the height and an increase in the width of microcrystalline structural units. The influence of bacterial degradation on the pore structure of Wudong coal was investigated using low-temperature nitrogen adsorption. The experimental results indicated that bacterial degradation led to the formation of microporous structures in Wudong coal. The characterization of fractal dimension indicated that the action of bacteria reduced the roughness of the pore surface of Wudong coal, promoted the development of pore structure, and increased the pore volume. CO₂ adsorption experiment indicated that bacterial degradation increased the adsorption capacity of Wudong coal for CO₂ from 1.72 to 2.53 mmol/g. In summary, utilizing bacteria to regulate the pore structure of coal samples and enhance the CO₂ sequestration capacity has important theoretical significance and application prospects.