Hydrophilic Fe3O4@C for High‐­Capacity Adsorption of 2,4‐Dichloro­phenol

Abstract A core–shell‐structured magnetic Fe 3 O 4 @C composite has been prepared from Fe 3 O 4 @RF (RF = resorcinol‐formaldehyde) through pyrolysis at 600 °C under a N 2 atmosphere. The resultant products were characterized by transmission electron microscopy (TEM), powder X‐ray powder diffraction (PXRD), X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, and thermogravimetric analysis (TGA). The Fe 3 O 4 @C composite has excellent particle monodispersity, a uniform particle diameter of ca. 200 nm, a magnetic saturation of 41.2 emu g –1 , and a high specific surface area of 247.3 m 2 g –1 owing to the existence of a bimodal micro‐macroporous system. Moreover, the carbon shell is graphitized but has good hydrophilicity, which is attributed to the existence of remnant oxygen‐containing groups. When applied as an adsorbent for the removal of 2,4‐dichlorophenol from water, Fe 3 O 4 @C shows a good dispersivity (0.2 g L –1 ) and an average maximum adsorption capacity of 131.83 mg g –1 with a fluctuation of less than 17 % over a wide pH range from 1 to 11 and can be quickly recovered within 30 s by the application of an external magnetic field (800 G). The adsorption performance of Fe 3 O 4 @C is revealed to be attributed to π–π electron donor–acceptor interactions between the electron‐rich conjugated aromatic groups of Fe 3 O 4 @C and electron‐deficient 2,4‐dichlorophenol. The high adsorption capacity and facile magnetic separation performance make our hydrophilic Fe 3 O 4 @C an ideal adsorbent for the removal of 2,4‐dichlorophenol from wastewater.