Simultaneous reductive and adsorptive removal of bromate from water using acid-washed zero-valent aluminum (ZVAl)

• Zero valent aluminum (ZVAl) is as the first time used to remove bromate from water.
• A acid-washing time (120 s) is required to treat aluminum powder to prepare ZVAl.
• The removal of bromate using ZVAl is attributed to reduction as well as adsorption.
• ZVAl exhibits a relatively high selectivity toward reduction of bromate over nitrate.
• ZVAl can be re-used for multi-cycles after the acid-washing regeneration treatments.

Zero valent aluminum (ZVAl), prepared from washing aluminum powder with acids, is employed for the first time to remove bromate from water. With a short acid-washing time (i.e., 120 s), the inherent layer of Al2O3 of aluminum powder could be removed, allowing ZVAl to react with bromate. The removal of bromate using ZVAl can be primarily attributed to the reduction of bromate to bromide and partially to the adsorption to the surface of ZVAl. Parameters influencing the removal of bromate were examined including temperature, pH, co-existing ions and ultrasonication. Temperature and pH were found to be critical parameters that affect the removal efficiency. ZVAl could completely remove bromate present in water (i.e., 78.1 μmol L−1) at 60 °C and pH = 3, while it became ineffective for removing bromate under alkaline conditions. The removal efficiency of ZVAl for bromate remained almost the same when bromate co-existed with other anions (e.g., sulfate, nitrate and phosphate). ZVAl also showed a high selectivity toward the reduction of bromate over nitrate. In addition, ultrasonication was demonstrated as a highly effective facilitator to enhance the removal of bromate using ZVAl. ZVAl was also re-used to remove bromate for multiple times after acid-washing regeneration. These results indicate that ZVAl is a promising material to remove bromate from water and the findings of this study can contribute to developing ZVAl to treat bromate-contaminated water.

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