Effect of hydroxyl functional groups on SO2 adsorption by activated carbon

The main objective of this study is to explore the influence mechanism of hydroxyl groups on the adsorption of SO 2 by activated carbon through experiments and simulations. The X-ray surface photoelectron spectroscopy (XPS) shows that the hydroxyl functional groups are conducive to the physical adsorption of SO 2 by activated carbon, but has little effect on its chemisorption. Through simulation, it can be found that the global maximum value of electrostatic potential (ESP) on van der Waals (vdW) surface changes from 16.597 to 53.925 kcal/mol after the hydroxyl group is embedded on the activated carbon, indicating that the hydroxyl group can increase the polarity of activated carbon. And the hydroxyl group can promote the physisorption of SO 2 and H 2 O on the edge of activated carbon through dipole-dipole interactions and hydrogen bonding, respectively. The coexistence of SO 2 , H 2 O and O 2 on the activated carbon can promote the physisorption of one another through the noncovalent interaction among them, especially the hydrogen bonding between SO 2 and H 2 O. Furthermore, the chemisorption of SO 2 on the activated carbon with hydroxyl groups hardly occurs. This study will guide the design of activated carbon for efficient SO 2 adsorption. • The effect of hydroxyl group is discussed in depth by simulation and experiment. • NaOH modification is not conducive to the adsorption of SO 2 on activated carbon. • Hydroxyl groups are conducive to SO 2 physisorption by dipole-dipole interactions. • The hydroxyl group has little effect on the chemisorption of SO 2 . • H 2 O promote SO 2 physisorption, while competing with SO 2 for adsorption.