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/Fe3O4 nanocomposites, in which carbon nanotubes (CNTs) were grafted to magnetic Fe3O4 particles by a facile hydrothermal method. The prepared CNTs/Fe3O4 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/Fe3O4 nanocomposites were evaluated for the removal of bisphenol A (BPA) in aqueous solution. It was found that the CNTs/Fe3O4 nanocomposites exhibited strong adsorption behavior for BPA in aqueous solution, and the adsorption of BPA onto the CNTs/Fe3O4 followed the Freundlich adsorption isotherm rather than the Langmuir adsorption isotherm. Moreover, the CNTs/Fe3O4 nanocomposites used, which were separated via an external magnetic field, were independently regenerated by methanol-wash or chemical oxidation methods (Fe2+/H2O2, Na2SO3/Fe2+, or UV/H2O2). The results demonstrated that as a recyclable adsorbent, CNTs/Fe3O4 nanocomposites can maintain a high recovery extent (similar to 98%) via magnetic separation and retain their adsorption behavior within the limits (+/- 1.34) after several adsorption-deactivation-regeneration cycles. (C) 2014 Elsevier B.V. All rights reserved.