Influence of the pore structure and surface chemical properties of activated carbon on the adsorption of mercury from aqueous solutions

•Activated carbons with different pore structure and surface chemical properties were prepared by modification process.•HgCl2 as a pollution target to evaluate the adsorption performance.•Influence of pore structure and surface chemical properties of activated carbon on adsorption of mercury was investigated. Reactivation and chemical modification were used to obtain modified activated carbons with different pore structure and surface chemical properties. The samples were characterized by nitrogen absorption–desorption, Fourier transform infrared spectroscopy and the Bothem method. Using mercury chloride as the target pollutant, the Hg2+ adsorption ability of samples was investigated. The results show that the Hg2+ adsorption capacity of samples increased significantly with increases in micropores and acidic functional groups and that the adsorption process was exothermic. Different models and thermodynamic parameters were evaluated to establish the mechanisms. It was concluded that the adsorption occurred through a monolayer mechanism by a two-speed process involving both rapid adsorption and slow adsorption. The adsorption rate was determined by chemical reaction.