Enhanced reductive debromination and subsequent oxidative ring-opening of decabromodiphenyl ether by integrated catalyst of nZVI supported on magnetic Fe3O4 nanoparticles

Abstract

The magnetic Fe0@Fe3O4 nanocomposite was prepared and used to achieve the reductive/subsequent oxidative ring-opening of decabromodiphenyl ether (BDE209) in this work. The characterization results indicated that the structure of the composite consisted of small nanoscale zero-valent iron (nZVI) particles surrounding the surface of Fe3O4 nanoparticle (NP). A 100% removal efficiency and 80% degradation efficiency of BDE209 was reached by the composite accompanied with ultrasound(called NP/US system) for 36h, which is higher than that obtained with conventional nZVI particles. Furthermore, the enhanced debromination and ring-opening of BDE209 was realized by a Fenton-like degradation process lasting for 12h after the addition of H2O2 to the NP/US reaction at 36h. Based on the degradation products identified, a two-stage reduction/oxidation degradation mechanism was proposed. During the first stage, which was reductive debromination, the major reductive activity of nZVI was efficiently enhanced in the presence of nano Fe3O4, which served as a catalyst to improve the stability of the nZVI nanoparticles and accelerate electron transfer, enhancing the degradation efficiency of BDE209. During the second stage, the oxidative ring-opening, the debromination products of BDE209 were proved to be attacked by abundant hydroxyl radicals generated both in the solution and on the surface of the Fe0@Fe3O4 nanoparticles. Thus, this work provides an efficient method to achieve the complete ring-opening of PBDEs using iron-based nanomaterials.