A Newly Dual-Cathode Electro-Fenton System: Self-Regulation Ph and Ferrous Species

Abstract

Optimizing and balancing H 2 O 2  accumulation and Fe 3+  reduction has become a stubborn problem in the electro-Fenton (EF) system. A novel dual-cathode (DC) EF system with gas diffusion electrode (GDE) and Fe/S doped multi-walled carbon nanotubes (Fe/S-MWCNT) modification active cathode (AC) was proposed for Bisphenol A (BPA) removal and showed superbly catalytic capability. This is attributed to the synergistic effect between two cathodes. The rate constant (for 20mg/L BPA ) of the DC system (0.062 min − 1 ) was much higher than that of the alone AC (0.005 min −1 ) and GDE (0.001 min − 1 ) system, and even more than 10.0 times of their sum. Impressively, this system had the ability of self-regulate pH to 3.0-4.0, enabling it to maintain high catalytic activity over a wide pH range, which avoided the disadvantage of the high cost of traditional EF in pre-acidification. The DC system exhibited long-term stability for BPA removal with easy activity regeneration facilitating to reduce the cost of replacing electrodes. This new EF system could not only minimize iron sludge production, but also maintain high catalytic activity, which was superior to homogeneous and heterogeneous EF systems.

Keywords: Dual-cathode, electro-Fenton, Bisphenol A, Active cathode