Organic compounds pollution, especially phenolic compounds, has been a serious problem recently. Multi-walled carbon nanotubes (MWCNTs) were oxidized by mixed acid oxidation method to remove phenolic compounds by adsorption. Five typical phenolic compounds including phenol, p-cresol, p-methoxyphenol, phydroxybenzaldehyde and p-nitrophenol were selected and to be adsorbed on MWCNTs and MWCNTs-O, respectively. Results showed that compared with the unmodified MWCNTs, the adsorption capacity of five phenolic compounds on MWCNTs-O increased significantly. The adsorption amount of five phenols on MWCNTs-O was different and the order was p-nitrophenol >p-methoxyphenol > p-hydroxybenzaldehyde > p-cresol > phenol. Adsorption isotherm data for the five phenols fitted Langmuir model well, which proved that phenolic compounds on MWCNTs was monolayer chemisorption. Surface functional groups analyzation of MWCNTs-O indicated that acidic oxygen-containing functional groups increased. TEM and Raman spectroscopy showed the winding degree of MWCNTs decreased, and overall dispersion and the degree of graphitization increased. π-π conjugation between vertical π electrons on MWCNTs-O and π electrons of phenolic compounds was formed and the electronic energy (EE) could be used as indicator for phenols adsorption on MWCNTs-O.
