Fe3O4/MWCNT as a heterogeneous Fenton catalyst: degradation pathways of tetrabromobisphenol A

Abstract

Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardant around the world. In this study, we report that iron oxide decorated on a magnetic nanocomposite (Fe3O4/MWCNT) was used as a heterogeneous Fenton catalyst for the degradation of TBBPA in the presence of H2O2. Fe3O4/MWCNT was prepared by a simple solvothermal method, whereby an iron source (Fe(acac)3) and a reductant (n-octylamine) were allowed to react in n-octanol solvent. Monodisperse Fe3O4 nanoparticles of consistent shape were uniformly dispersed on the nanotubes. Samples were characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area measurement, and vibrating sample magnetometry. The samples effectively catalyzed the generation of hydroxyl radicals (·OH) from H2O2, which degraded and subsequently mineralized the TBBPA. The whole process took four hours at near neutral pH. A degradation pathway for the system was proposed following analysis of intermediate products by gas chromatography-mass spectrometry. The quantification of Fe2+ and Fe3+ distribution before and after the recycling test of the composite were explored by X-ray photoelectron spectroscopy, in order to explain the stability and recyclability of the composite. Analysis of the results indicated that the magnetic nanocomposite is a potentially useful and environmentally compatible heterogeneous Fenton's reagent with promising applications related to pollution control.