Adsoption of voltatile organic compounds on activated carbon surface: a DFT study

Abstract

In this work, the shapes of stable structures for organic compounds adsorption on activated carbon (AC) surface at pure- and Fe/Zn-doped states are obtained at the PBEPBE/6-31G(d) level of theory. The binding between sites of molecules and surface is focused on ring center and functional groups. For doped surfaces (Fe@AC, Zn@AC), the stable interactions are formed favorably at Fe/Zn sites and functional groups. The adsorption energy values of molecules on surfaces range from -6.2 to -8.3 kJ.mol^-1 for AC and from -7.4 to -49.3 kJ.mol^-1 for Zn@AC and -166.3 to -292.7 kJ.mol^-1 for Fe@AC. Noticeably, AIM and NBO results indicate the existence and strength of intermolecular interactions upon complexation. The H‧‧‧C*/π weak forces play an important role in the configuration strength for AC. Besides, the O‧‧‧Fe/Zn electrostatic interactions with partly covalent nature contribute significantly to the stability of configurations for Fe/Zn doped AC. The addition of Fe onto AC enhances the adsorption ability of organic molecules as compared to Zn-doping.