Elimination of bromate from water using aluminum beverage cans via catalytic reduction and adsorption

Abstract

While zero valent aluminum (ZVAl) is a promising reductant for eliminating bromate from water, ZVAl is typically obtained from reagent grade aluminum. As used aluminum beverage can is the most common aluminum waste, it can be conveniently used to prepare ZVAl. Thus, in this study aluminum beverage cans are employed for the first time as a plentiful and easily accessible aluminum source to afford ZVAl for eliminating bromate from water. As aluminum is easily oxidized to form aluminum oxide, aluminum can pieces (ACPs) are pre-treated with HCl for removing the oxide layer to afford ZVAl. While non-acid-treated ACP is ineffective to remove bromate, the acid-treated ACP successfully eliminates bromate from water completely. Bromate elimination by ACP is attributed to reduction of bromate to bromide by the reactive sites of ACP and adsorption of bromate to the surface of ACP. Bromate elimination by ACP also proceeds much faster at higher temperatures and low pH values, while the alkaline condition causes serious negative effects on bromate elimination. Besides, oxalic acid is found to facilitate bromate elimination not only on the kinetics but also reduction to bromide because the passivation layer is suppressed in the presence of oxalic acid. ACP could also be reused and the acid-washing regeneration could enable used ACP to restore its reactive sites for bromate elimination. This study successfully demonstrates the valorization of aluminum beverage cans for mitigating the toxic bromate and the findings here provide useful information and insights to develop aluminum beverage cans for controlling pollutants in water.

Keywords: Acid-washing; Aluminum beverage cans; Bromate; Bromide; Reduction.