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.