Controllable Preparation And Catalytic Performance Analysis Of Heterogeneous Electro-Fenton Catalysts

Acid mine drainage (AMD) contains a large amount of ferrous iron and the recovery of iron oxides from the AMD has been of extensive research interest. Here we report a novel air-cathode fuel cell strategy to in-situ utilize ferrous iron in the AMD for the fabrication of heterogeneous electro-Fenton catalysts. Three types of nano-structured iron oxide/graphite felt (GF) composites, including FeOOH/GF, Fe2O3/GF and Fe3O4/GF, were fabricated from a synthetic AMD and their catalytic activities towards the electro-Fenton reaction were evaluated at neutral pH with Rhodamine B (RhB) as a probe pollutant. The electro-Fenton system with GF cathode only removed 30 ± 1.4% of RhB after 120 min of reaction. In comparison, the RhB removal efficiencies were significantly improved to 62.5 ± 2.0%,95.4 ± 0.9% and 95.6 ± 0.7% when the FeOOH/GF, Fe2O3/GF and Fe3O4/GF composites were used as the cathodes, respectively. Among the three types of composites, the Fe3O4/GF exhibited the highest electro-Fenton catalytic activity whereas the lowest activity was observed for the FeOOH/GF. The air-cathode fuel cell technology has a potential for iron recovery from the AMD, and provides an effective way for fabricating heterogeneous electro-Fenton catalyst with high catalytic activity and good stability.The operating condition of fuel cell was optimized in order to further improve the catalytic activity of carbon supported iron oxides. The catalytic activity of prepared Fe3O4/GF gradually increased as the pH of anodic solution increased from 5.0 to 7.5, while steeply decreased when the pH rose to 9.0. The concentrations of Fe(II) and carbonate also exhibit influences on the catalytic activities of prepared composites, with the highest activity obtained at Fe(II) concentration of 30mM and carbonate concentration of 50mM.Fe3O4/GF composite was obtained by operating the fuel cell under the optimized condition (solution pH=7.5, the outer resistance=1000Ω, C Fe(Ⅱ)= 30mM, CNaHCO3= 50mM). The degradation efficiency of RhB by using such a catalyst achieved as high as 99.6±0.4% in 10 h, and total mineralization of RhB was observed after 24 hours of reaction.