Influence of alkali-activated potassium persulfate solution immersion on wettability and pore structure of anthracite coal: Experimental study and molecular simulation

The effects of alkali-activated potassium persulfate solution (AAP) immersion on coal surface wettability and pore structure were systematically investigated in this study. Experimental results indicated when mass fraction of potassium persulfate and sodium hydroxide was 1.5 % and 0.5 %, activation temperature was 30 °C, anthracite wettability was improved most significantly. Under the optimal conditions, capillary reverse osmosis height of the AAP-treated coal samples reached 8.1 cm, and water-droplet contact angle θ decreased markedly from 112.97° to 55.08°. Relative content of oxygen-containing groups –C O and OH–OH increased most significantly. Coal molecular structure models were constructed and theoretical simulation results showed that both H 2 O adsorption capacity and adsorption heat increased after AAP immersion, and the AAP-treated coal samples can absorb a large number of water molecules even at lower pressure. Spray dust-suppressing efficiency increased from 33.42 % to 74.65 % by using AAP. The radicals (SO 4 · − and · OH) in AAP could in-situ oxidize and corrode active organic molecules in coal matrix, expanding original pores and creating new pores-fractures on coal surface. Average pore diameter increased by 17.40 %, while specific surface area decreased by 51.14 %, and internal pore surface became smoother. Additionally, methane adsorption constant a and b value of the AAP-immersed coal samples decreased by 6.42 % and 32.68 %. Compared with previous reports on wettability regulation, this study not only enhanced the wettability of coal samples, but also improved their pore structure. These findings provide crucial technical support for innovative development of dust suppression and outburst prevention technologies in coal mines.