A magnetic nano-scaled composite was synthesized by self-assembly of cationic surfactant octadecyl dimethyl hydroxyethyl ammonium nitrate (SN) into natural mineral diatomite via a 'dissolution and reassembly' method. Fourier transform infrared (FT-IR), elemental analysis, scanning electron microscopy (SEM), transmission electron microscope (TEM), surface area and magnetic analysis were performed to characterize the achieved composites. The results indicated that SN and Fe3O4 nanopartilces were successfully inserted into the diatomite matrix. Under the same condition, the mixed phenols adsorption experiments showed that the maximum adsorption capacity of phenols by the composite was in order of 2,4,6-trichlorophenol > 2,6-dichlorophenol > 2,4-dichlorophenol > p-nitrophenol > m-methylphenol > phenol, the same as the competitive adsorption ability. The adsorption process obeyed the Langmuir isothermal model. 2,6-Dichlorophenol was used as a representative contaminant to further investigate the mechanism of adsorption. Electrostatic interaction and hydrophobic stacking effect might play important roles in the adsorption towards organic phenols. Owing to the embedded magnetic Fe3O4, the composite was able to be separated easily from liquid media under an external magnetic field. The further calcination of the used composites showed a possibility to deliver new magnetic mesoporous absorbents for further use. (C) 2017 Elsevier B.V. All rights reserved.