Design of an electro-Fenton system with a novel sandwich film cathode for wastewater treatment

In this study, we demonstrate an electro-Fenton (E-Fenton) system constructed with a novel sandwich film cathode (SFC). For the fabrication of SFC, Fe2+-chitosan (Fe-CHI) was first deposited on foam nickel (Fe-CHI/Ni). Then two pieces of Fe-CHI/Ni was used to fasten one piece of activated carbon fiber (ACF) to obtain a Fe-CHI/Ni|ACF|Fe-CHI/Ni sandwich film cathode. We interestingly found that this SFC based E-Fenton system could effectively degrade rodamine B with in situ generating both hydrogen peroxide and iron ions. Its degradation efficiency was significantly higher than those of the E-Fenton systems constructed with composite cathodes of carbon nanotubes with Fe@Fe2O3 core-shell nanowires or Cu2O nanocubes reported in our previous studies. Hydrogen peroxide electrogenerated through the reduction of O2 adsorbed on the sandwich film cathode and the iron ions produced by the leakage from Fe2+-chitosan film during the E-Fenton reaction were, respectively, monitored, providing clues to understand the high efficiency of this novel SFC based E-Fenton system. More importantly, this low-cost sandwich film cathode was very stable and could be reused without catalytic activity decrease, suggesting its potential application in the wastewater treatment.