Utilization of spent aluminum for p-arsanilic acid degradation and arsenic immobilization mediated by Fe(II) under aerobic condition

• A strategy of “waste control by waste” for treating organic arsenic was proposed.
• Fe(II) significantly enhances the yield of OH in aerobic Al beverage cans system.
• Arsenic can be immobilized at pH = 6.0 with Fe(III)/Al(III) as flocculating agents.
• The corrosion of metal aluminum would not cause Al(III) pollution in effluent.

As a typical feed additive, p-arsanilic acid (p-ASA) potentially brings about the risks of toxic inorganic arsenic contamination in natural environments. In this study, the potential utilization of the spent aluminum beverage cans (AlBCs) for the degradation of p-ASA and immobilization of the produced inorganic arsenic was unprecedentedly evaluated. The results show that the degradation efficiency of p-ASA increased with decreasing solution pH, and p-ASA can be completely degraded to inorganic arsenic species within 180 min at pH ⩽ 2.0 in the aerobic AlBCs/Fe(II) system. The optimal performance for p-ASA degradation was obtained at Fe(II) concentration of 0.2 mM. But under anaerobic condition, the degradation of p-ASA was significantly retarded due to the inhibited production of H2O2 by the absence of oxygen. In the AlBCs/Fe(II) system, Fe(II) did not only catalytically transform H2O2 to OH via Fenton reaction, but also, combining with Al(III) ion, acts as preferable flocculant for inorganic arsenic removal. Thus, the produced As(V) species can be completely removed via the formation of As(V)-bearing amorphous hydrous Al/Fe precipitates by simple adjusting solution pH to 6.0. Generally, the present study provides a cost-effective and environmentally friendly strategy for degrading organic arsenic pollutants and immobilizing the hypertoxic inorganic arsenic species.

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