Roles of functional groups and irons on bromate removal by FeCl3 modified porous carbon

Ferric chloride modified lotus stem-based porous carbon (FeCl₃-LSPC) was synthesized for the removal of bromate from aqueous solutions. The adsorbent characterization indicated that the BET surface area and pore volume were enlarged by the modification of FeCl₃, at the same time, the reductive functional group of C-OH was enhanced in the FeCl₃-LSPC. The FeCl₃-LSPC exhibited greater bromate removal performance in a wide pH range compared to other absorbents. The mechanisms of bromate removal were analyzed by XPS and two-dimensional correlation analysis of FTIR (2D-FTIR-COS). The main removal mechanism of bromate is reduction and C-OH group was responsible for bromate reduction. During the bromate reduction process, the Fe³⁺/Fe²⁺ redox couple served as electron shuttle to facilitate the electron transfer from C-OH group to bromate. The main functional groups involved in bromate reduction process followed the reaction order: C-OH > CO > COOH > CH.