A pH self-regulated three-dimensional electro-Fenton system with a bifunctional Fe-Cu-C particle electrode: High degradation performance, wide working pH and good anti-scaling ability

Abstract

Three-dimensional electro-Fenton system (3DEF) shows great prospect for wastewater treatment. However, the development of an efficient particle electrode with wide working pH and good anti-scaling ability still remains a challenge. In this study, a novel iron-copper-carbon black (Fe-Cu-C) composite was fabricated through a one-step process of pyrolyzing the metal-resin precursors and worked as the particle electrode in the three-dimensional electro-Fenton reactor. In this system with electrodes polarization, the anode-to-cathode flow mode created a locally acidic zone in the packed bed with Fe-Cu-C particle, which facilitated the H2O2 generation from 2-electron reduction of O2 and decomposition into •OH via heterogeneous Fenton reaction. Consequently, it was found that average p-Nitrophenol (p-NP) removal efficiency of 88% and average COD removal efficiency of over 76% were achieved even after 6 h continuous treatment in the continuous-flow 3DEF system packed with Fe-Cu-C particles at a current density of 20 mA cm−2 and flow rate of 1.33 mL min−1. Noticeably, the flow-through 3DEF had the appreciable anti-scaling ability to resist the deactivation of particle electrodes induced by hardness ions and showed little sensitivity to solution pH in the range of 4.0–10.0 with specific energy consumption of approximately 0.089 kW h g−1 COD. Generally, this material could be used as a low-cost particle electrode in combination with flow-through 3DEF for practical wastewater treatment.