Sulfidated nanoscale zero-valent iron dispersed in dendritic mesoporous silica nanospheres for degrading tetrabromobisphenol A

Sulfidated nanoscale zero-valent iron (S-NZVI) has attracted significant attention in pollutant remediation due to its higher electron selectivity than NZVI. However, the agglomeration behavior of S-NZVI particle limits its practical application. In this study, S-NZVI was synthesized and dispersed in dendritic mesoporous silica nanospheres (S-NZVI/DMSN) to remove tetrabromobisphenol A (TBBPA) in groundwater. The structural characterization and degradation results illustrated that the dendritic pores of DMSN not only improved the dispersion of S-NZVI particles, but also enhanced the accessibility of pollutants to S-NZVI. The specific surface area of the S-NZVI/DMSN reached 136.2 m2 g-1, which was 2.68 times larger than that of S-NZVI (50.8 m2 g-1). At a S/Fe molar ratio of 0.1 and Si/Fe mass ratio of 1.0, the TBBPA degradation efficiency by S-NZVI/DMSN reached 91.4%, which exceeded that of S-NZVI (66.3%), and the degradation rate constants (0.078 L (mg h)-1) was 2.86 times higher than that of S-NZVI (0.027 L (mg h)-1). The S-NZVI/DMSN could remain high TBBPA degradation performance (76.3%) after even five cyclic degradations. Approximately 70.5% of S-NZVI/DMSN and 1% of S-NZVI successfully passed through the sand column. The much better sustained reactivity and transportability of S-NZVI/DMSN indicated that it could penetrate soil aquifers and degrade TBBPA in groundwater.