Abstract
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► Fe(II)–Al(III) LDHs were synthesized by ultrasound-assisted co-precipitation method. ► The Fe–Al (30min) exhibited highly reduction reactivity on bromate. ► Pseudo-first-order model described the experimental data well. ► The mechanisms of bromate removal were proposed.
Bromate is recognized as an oxyhalide disinfection byproduct in drinking water. In this paper, Fe(II)–Al(III) layered double hydroxides (Fe–Al LDHs) prepared by the ultrasound-assisted co-precipitation method were used for the reduction of bromate in solution. The Fe–Al LDHs particles were characterized by X-ray diffractometer, scanning electron microscopy and thermogravimetry–differential scanning calorimetry. It was found that ultrasound irradiation assistance promoted the formation of the hydrotalcite-like phase and then improved the removal efficiency of bromate. In addition, the effects of solid-to-solution ratio, contact time, initial bromate concentration, initial pH, coexisting anions on the bromate removal were investigated. The results showed the bromate with an initial concentration of 1.56μmol/L could be completely removed from solution by Fe–Al LDHs within 120min. When the initial bromate concentration was 7.81μmol/L, the Fe–Al LDHs with irradiation time of 30min exhibited the optimum removal efficiency and the bromate removal capacity (qe) was 6.80μmol/g. In addition, the appearance of sulfate and production of bromide were observed simultaneously in this process, which suggested that ion-exchange between sulfate and bromate, and the reduction of bromate to bromide by Fe2+ were the main mechanisms responsible for the bromate removal by Fe–Al LDHs.