Recyclable CNTs/Fe3O4 magnetic nanocomposites as adsorbents to remove bisphenol A from water and their regeneration

This paper presents the synthesis of magnetic carbon nanotube adsorbents, CNTs/Fe 3 O 4 nanocomposites, in which carbon nanotubes (CNTs) were grafted to magnetic Fe 3 O 4 particles by a facile hydrothermal method. The prepared CNTs/Fe 3 O 4 nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), the Brunauer–Emmett–Teller (BET) surface areas, and magnetic property measurements. The adsorption behaviors of the CNTs/Fe 3 O 4 nanocomposites were evaluated for the removal of bisphenol A (BPA) in aqueous solution. It was found that the CNTs/Fe 3 O 4 nanocomposites exhibited strong adsorption behavior for BPA in aqueous solution, and the adsorption of BPA onto the CNTs/Fe 3 O 4 followed the Freundlich adsorption isotherm rather than the Langmuir adsorption isotherm. Moreover, the CNTs/Fe 3 O 4 nanocomposites used, which were separated via an external magnetic field, were independently regenerated by methanol-wash or chemical oxidation methods (Fe 2+ /H 2 O 2 , Na 2 SO 3 /Fe 2+ , or UV/H 2 O 2 ). The results demonstrated that as a recyclable adsorbent, CNTs/Fe 3 O 4 nanocomposites can maintain a high recovery extent (∼98%) via magnetic separation and retain their adsorption behavior within the limits (±1.34) after several adsorption–deactivation–regeneration cycles.