Functionalized construction of biochar with hierarchical pore structures and surface O-/N-containing groups for phenol adsorption

[Display omitted] •O/N-groups on pore surface of biochar forms hierarchical-functionalized structure.•Mesoporous structure on biochar surface mainly determines adsorption of phenol.•Hydroxyl group strengthens phenol adsorption for increased electrostatic effect.•N-6 enhances the van der Waals force for the change of biochar adsorption sites. Volatile organic compounds (VOCs) seriously endanger human health due to their bioaccumulation and carcinogenic effects, while biochar adsorption method is regarded as one of the most potential VOCs removal technologies. In order to clarify the structure-activity relationship of biochar adsorption of VOCs, corn straw was used as a biomass raw material for chemically activated biochar preparation and liquid-phase adsorption experiments. The simulations including molecular dynamics simulations and quantum chemical simulations were carried out to verify the relevant conclusions. The results show that abundant O-/N-containing functional groups are constructed on the pore surface of chemically activated biochar, forming a typical hierarchical-functionalized pore structure. The hierarchical-functionalized pore structure has an ideal promotion effect on the adsorption of phenol. Specifically, mesoporous structure on biochar surface mainly determines adsorption of phenol. The hydroxyl group strengthens the adsorption of phenol, due to the increased electrostatic effect, while N-6 enhances the van der Waals force for the change of adsorption site, thereby strengthening the adsorption of phenol. This work provides theoretical support for the practical application of biochar for efficient VOCs removal technology.