Mechanistic Insight into Efficient Bromate Removal with Core-Shell Fe@Fe2O3 Nanowires

摘要

In this study,we systematically investigated the removal of bromate with core-shell Fe@Fe2O3 nanowires (CSFN) at neutral pH,especially the effects of surface bound ferrous ions and molecular oxygen.Although the hypobromous acid (HBrO) intermediate was generated at the initial stage,it could finally be oxidized to Br-with 100％ recovery.We interestingly found ferrous ions bound on the surface of CSFN could directly reduce bromate,and also act as an electron mediator to accelerate the transfer of electron from the inner iron core to the iron oxide shell,thus contributed to the BrO3-removal.Moreover,molecular oxygen could compete electrons from either Fe2+ or Fe0 to generate reactive oxygen species (·O2,H2O2,·OH),during the bromate removal process.Among these reactive oxygen species,·O2-and H2O2 promoted the bromate removal,but ·OH exhibited an inhibition effect.On the basis of bromide species analyses and CSFN characterization results,we proposed a bromate removal mechanism of core-shell Fe@Fe2O3 nanowires.This study can deepen our understanding on the bromate removal with zero valent iron,and also shed light on the design of advanced bromate removal materials.