Process Regulation Of In-situ Fabrication Of Heterogeneous Electro-fenton Catalyst From Acid Mine Drainage

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 Fe₃O₄/GF?graphite felt?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 structure and activity 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⁺lower iron content in the composite and thus present a detrimental effect on the EF catalytic activity of the prepared composite.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 AC-FC technology is efficient to simultaneously remove heavy metal cations and recover highly active heterogeneous EF catalyst from real AMDs rich in Fe²⁺.In addition,surface modification of the graphite support is suggested to be an effective strategy to enhance the EF catalytic activity of Fe₃O₄/GF composite prepared from AMD.Four surface modification methods,including H₂O₂ treatment,electro-oxidation treatment,KOH treatment and N₂H₄·H₂O treatment,are applied on commercial graphite felt?GF?.Structures and properties of the modified GFs are characterized,and EF catalytic activities of corresponding Fe₃O₄/GF composites prepared from synthetic AMD are evaluated.The results demonstrate that surface modification of the GF not only improves the electro-oxidation of Fe?II?in the AC-FC,but also promotes the electro-generation of H₂O₂ in heterogeneous EF process.Notably,the concentration of H₂O₂generated on N₂H₄·H₂O-treated GF?GF-N₂H₄?is more than three times that generated on raw GF?GF-Raw?,and iron content in the prepared Fe₃O₄/GF-N₂H₄ composite is more than twice that in the Fe₃O₄/GF-Raw composite.Application of GF-N₂H₄ to the treatment of real AMD greatly enhances the recovery efficiency of ferrous iron.The Fe₃O₄/GF-N₂H₄ composite prepared from real AMD displays high catalytic activity and good stability in EF process for mineralizing a variety of refractory organic contaminants.The AC-FC technology is expected to provide a prospective approach for fabricating green and efficient EF catalyst from real AMD rich in Fe²⁺and it also conforms to the concept of sustainable development.