In Situ Fabrication of Electro-Fenton Catalyst from Fe²⁺ in Acid Mine Drainage: Influence of Coexisting Metal Cations

The air-cathode fuel cell (AC-FC) technology provides a facile approach to in situ utilize Fe²⁺ in acid mine drainage (AMD) for the fabrication of iron oxide/carbon composite with electro-Fenton (EF) catalytic activity. Herein, the impacts of coexisting metal cations other than the Fe²⁺ in AMD on such an EF catalyst fabrication process are investigated. The results show that coexisting metal cations are able to be introduced into the Fe₃O₄/GF composite and influence iron content in it. The Ni²⁺, Zn²⁺, Al³⁺, and Cu²⁺ in AMD lower iron content in the prepared composite and thus present a detrimental effect on its EF catalytic activity. In comparison, the Co²⁺ and Mn²⁺ hardly affect iron content in the composite. Instead, they are doped into the Fe₃O₄ structure to give mixed-metal oxides with enhanced EF catalytic activities. Practice on the treatment of real AMDs suggests the practical effectiveness of AC-FC technology for the simultaneous removal of heavy metal cations and fabrication of heterogeneous EF catalyst from real AMDs. Notably, the AC-FC technology is expected to provide a prospective approach for fabricating transition metal doped iron oxides from AMD rich in Fe²⁺ and transition metal cations.