Recyclable CNTs/Fe sub(3)O sub(4) 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 sub(3)O sub(4) nanocomposites, in which carbon nanotubes (CNTs) were grafted to magnetic Fe sub(3)O sub(4) particles by a facile hydrothermal method. The prepared CNTs/Fe sub(3)O sub(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 sub(3)O sub(4) nanocomposites were evaluated for the removal of bisphenol A (BPA) in aqueous solution. It was found that the CNTs/Fe sub(3)O sub(4) nanocomposites exhibited strong adsorption behavior for BPA in aqueous solution, and the adsorption of BPA onto the CNTs/Fe sub(3)O sub(4) followed the Freundlich adsorption isotherm rather than the Langmuir adsorption isotherm. Moreover, the CNTs/Fe sub(3)O sub(4) nanocomposites used, which were separated via an external magnetic field, were independently regenerated by methanol-wash or chemical oxidation methods (Fe super(2+)/H sub(2)O sub(2), Na sub(2)SO sub(3)/Fe super(2+), or UV/H sub(2)O sub(2)). The results demonstrated that as a recyclable adsorbent, CNTs/Fe sub(3)O sub(4) nanocomposites can maintain a high recovery extent ( similar to 98%) via magnetic separation and retain their adsorption behavior within the limits ( plus or minus 1.34) after several adsorption-deactivation-regeneration cycles.