Combined adsorption and catalytic ozonation for removal of endocrine disrupting compounds over MWCNTs/Fe3O4 composites

Abstract

MWCNTs/Fe3O4 magnetic composites, combined adsorption and catalytic ozonation behavior, were synthesized by a hydrothermal process. The synthesized MWCNTs/Fe3O4 composites were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), element analysis and Brunauer-Emmett-Teller (BET) surface area. The adsorption performance and catalytic activity of MWCNTs/Fe3O4 for BPA removal in aqueous solution were evaluated. The results showed that the synthesized MWCNTs/Fe3O4 exhibited an excellent adsorption ability and catalytic ozonation activity owning to its large specific surface areas, hollow tube channels and abundant surface oxygen-containing groups, leading to high adsorption for BPA and O3, high retention and utilization of O3 molecules on the composites. In addition, the catalytic ozonation performance of MWCNTs/Fe3O4 could be improved by increasing surface oxygen-containing groups to accelerate O3 decomposition, thus producing more OH radicals. Moreover, BPA removal efficiency could be improved by increasing dose of catalyst, pH value and the concentration of humic acid (HA). The fluorescence spectra and OH radicals measurement displayed that HA could greatly increase OH radicals via inducing more surface oxygen-containing groups on the catalyst, thus, promoting BPA removal. Furthermore, MWCNTs/Fe3O4 showed the great stability and durability during several reaction recycles.