Degradation of decabromodiphenyl ether by nano zero-valent iron immobilized in mesoporous silica microspheres

► Reactive mesoporous silica spheres (SiO 2@FeOOH@Fe) was synthesized. ► SiO 2@FeOOH@Fe presented a great capability of removing BDE209. ► The importance of hydrogen ion in removing BDE209 by SiO 2@FeOOH@Fe has been proved. ► SiO 2@FeOOH@Fe was agglomeration-resisting and good performances in magnetic separation. The agglomeration of nanoparticles reduces the surface area and reactivity of nano zero-valent iron (NZVI). In this paper, highly dispersive and reactive NZVI immobilized in mesoporous silica microspheres covered with FeOOH was synthesized to form reactive mesoporous silica microspheres (SiO 2@FeOOH@Fe). The characteristics of SiO 2@FeOOH@Fe were analyzed by transmission electron microscopy, Fourier transform infrared spectroscopy simultaneous thermal analysis, X-ray photoelectron spectroscopy, and Brunnaer–Emmett–Teller surface area analysis. The mean particle size of the reactive mesoporous silica microspheres was 450 nm, and its specific surface area was 383.477 m 2 g −1. The degradation of dcabromodiphenyl ether (BDE209) was followed pseudo-first-order kinetics, and the observed reaction rate constant could be improved by increasing the SiO 2@FeOOH@Fe dosage and by decreasing the initial BDE209 concentration. The stability and longevity of the immobilized Fe nanoparticles were evaluated by repeatedly renewing the BDE209 solution in the reactor. The stable degradation of BDE209 by SiO 2@FeOOH@Fe was observed within 10 cycles. Agglomeration-resistance and magnetic separation of SiO 2@FeOOH@Fe were also performed. The improved dispersion of SiO 2@FeOOH@Fe in solution after one-month storage and its good performance in magnetic separation indicated that SiO 2@FeOOH@Fe has the potential to be efficiently applied to environmental remediation.