Promoting SO4·– and ·OH Generation from Sulfate Solution toward Efficient Electrochemical Oxidation of Organic Contaminants at a B/N-Doped Diamond Flow-Through Electrode

Abstract

Electrochemical oxidation via in situ-generated reactive oxygen species (ROS) is effective for the mineralization of refractory organic pollutants. However, the oxidation performance is usually limited by the low yield and utilization efficiency of ROS. Herein, a B/N-doped diamond (BND) flow-through electrode with enhanced SO₄^·–/^·OH generation and utilization was designed for electrochemical oxidation of organic pollutants in sulfate solution. Both its SO₄^·–/^·OH yields and SO₄^·– selectivity were improved by regulating B/N doping, and the production and utilization of SO₄^·–/^·OH were facilitated by flow-through mode. BND showed fast PFOA oxidation with kinetic constants of 2.56–4.58 h^–1 at low current densities of 2.0–5.0 mA cm^–2. Its energy consumption for PFOA oxidation was 2.15–6.46 kWh m^–3, which was lower than those of state-of-the-art electrodes under similar conditions. The BND anode was also efficient for treating organic fluorine wastewater and coking wastewater. The superior performance was contributed by its enhanced SO₄^·–/^·OH yields and utilization, as well as high SO₄^·– selectivity.