Enhanced Reduction of Bromate from Water by AC/S-nZVI: Performance and Mechanism

Abstract

Nanoscale zero-valent iron (nZVI) particles are one of the most efficient materials for water treatment. However, their poor resistance to oxidation is one of the major reported drawbacks. This study synthesized a series of nZVI particles modified by sulfides (S-nZVI) and then supported on activated carbon (AC/S-nZVI). Batch experiments of bromate removal by S-nZVI or AC/S-nZVI were performed. Three process parameters [dissolved oxygen (DO), S/Fe, and dose of S-nZVI] were optimized by the response surface methodology (RSM) combined with the Box–Behnken design (BBD). The highest bromate removal rate (90%) was achieved in 90 min with a 40-mg/L dose of the S-nZVI composites (S/Fe molar ratio of 0.09) and a DO value of 8.0±0.5 mg/L. The mechanism of bromate reduction by AC/S-nZVI was discussed. The oxidation resistance was improved due to the presence of iron sulfides (FeSx). The excellent bromate removal efficiency achieved by AC/S-nZVI likely is due to the synergistic effects of AC and S-nZVI. Overall, our work provides a promising, efficient method for removing bromate in high DO water.