Effects of SDBS and BS-12 on functional groups/wettability of multicomponent acidified lignite

•A multicomponent acid solution consisting of SDBS,BS-12, HF and C6H8O7 was used to acidifie coal samples.•Acidification treatment can promote the formation of oxygen-containing functional groups CO and CO.•Provide an effective method for realizing high-efficiency clean mining of coal.•The micro mechanism of wettability was explained using molecular dynamics software.