Fabrication of magnetic polybenzoxazine-based carbon nanofibers with Fe3O4 inclusions with a hierarchical porous structure for water treatment

Hierarchical porous, magnetic Fe3O4@carbon nanofibers (Fe3O4@CNFs) based on polybenzoxazine precursors have been synthesized by a combination of electrospinning and in situ polymerization. The benzoxazine monomers could easily form thermosetting nanofibers by in situ ring-opening polymerization and subsequently be converted into CNFs by carbonization. The resultant fibers with an average diameter of 130 nm are comprised of carbon fibers with embedded Fe3O4 nanocrystals, and could have a high surface area of 1885 m2 g−1 and a porosity of 2.3 cm3 g−1. Quantitative pore size distribution and fractal analysis were used to investigate the hierarchical porous structure using N2 adsorption and synchrotron radiation small-angle X-ray scattering measurements. The role of precursor composition and activation process for the effects of the porous structure is discussed, and a plausible correlation between surface fractal dimension and porous parameter is proposed. The Fe3O4@CNFs exhibit efficient adsorption for organic dyes in water and excellent magnetic separation performance, suggesting their use as a promising adsorbent for water treatment, and also provided new insight into the design and development of a carbon nanomaterial based on a polybenzoxazine precursor.