Yolk-shell Fe/FeS@SiO2 particles with enhanced dispersibility, transportability and degradation of TBBPA

In this study, Fe/FeS@SiO 2 yolk-shell particles (Fe/FeS@SiO 2 YSPs) were synthesized, characterized, and applied to tetrabromobisphenol A (TBBPA) removal in simulated groundwater. The X-ray photoelectron spectroscopy, X-ray diffraction, Scanning electron microscopy, transmission electron microscopy and Brunauer Emmett Teller results revealed that Fe/FeS@SiO 2 YSPs possess special structures, including active cores, mesoporous networks, shells, hollow cavities and a large surface area (85 m 2 /g vs. 8 m 2 /g) compared to Fe/FeS. The mobility of the synthesized particles in porous media was simulated with sand column experiments. Fe/FeS@SiO 2 YSPs showed a much better transportability (83.02% of particles successfully transported through the column) than Fe/FeS particles (only 1.68%), related to the better suspension stability and much lower particle surface charge (−22.7 mV vs. −7.6 mV) at neutral pH. Improved TBBPA reduction performance in synthetic solution was observed for Fe/FeS@SiO 2 YSPs over bare Fe/FeS. The transformation pathway of TBBPA was studied in detail, revealing the formation of tri-BBPA, di-BBPA, mono-BBPA and BPA as the main products. In brief, thanks to the hollow mesoporous silica spheres (HMSS) coated on the surface of Fe/FeS particles, Fe/FeS@SiO 2 YSPs showed an enhanced dispersibility, transportability and degradation of TBBPA in simulated groundwater. The results in this study proved that Fe/FeS@SiO 2 YSPs are a promising material for in situ remediation of TBBPA in soil and groundwater.