Electro‐Fenton Degradation of Methylene Blue Using Polyacrylonitrile‐Based Carbon Fiber Brush Cathode

Abstract A polyacrylonitrile‐based carbon fiber brush (PAN‐CFB) cathode was firstly used to decolorize and degrade methylene blue (MB) in Na 2 SO 4 solution via electro‐Fenton reaction between H 2 O 2 from oxygen reduction and ferrous ions (Fe 2+ ) externally added. The optimal current value for H 2 O 2 production was 300 mA, with a maximum H 2 O 2 concentration of 185 mg L −1 and current efficiency of 68% after 60 min, indicating that PAN‐based CF is a promising electrode material for 2 e − oxygen reduction reaction. Additionally, the effect of different parameters, such as the initial pH of the dye solution, Fe 2+ and initial dye concentration on the decolorization efficiency, and COD removal was thoroughly investigated in simulated wastewater containing MB. The results showed that the electro‐Fenton system using the PAN‐CFB cathode had a wide applicable pH range 3.00–7.00, and the optimal Fe 2+ concentration was 0.3 mmol L −1 . Moreover, under the conditions of 300 mA current, pH 3.00, and 0.3 mmol L −1 Fe 2+ , a nearly 100% color removal after 30 min, 95.9% chemical oxygen demand (COD) removal and the low electrochemical energy consumption of 11.6 kWh kg −1 COD after 60 min for 100 mg L −1 MB solution were obtained.