High-efficiency electrochemical activation of H2O2 into ·OH enabled by flow-through FeOCl-modified carbon electrode for organic pollutants degradation

The heterogeneous Fenton technology as the promising substitution to traditional Fenton process shows the advantages of wide effective working pH and feasible catalyst recovery, but it suffers from the problems of low ·OH productivity caused by poor H2O2 utilization. In this work, a flow-through electrochemical H2O2 activation system was designed using FeOCl-modified carbon fiber as free-standing cathode for high-efficiency ·OH production. The ·OH yield of flow-through electrode reached up to 0.99 mmol L−1 with a remarkable H2O2 utilization rate of 9.94%, which was comparable to state-of-the-art heterogeneous Fenton catalysts. By virtue of the efficient ·OH production, the flow-through electrode could achieve 96.7–99.8% of degradation and 32.4–67.4% of mineralization for different pollutants at pH 7. The flow-through electrode could effectively subduct chemical oxygen demand of secondary effluent of coking and petrochemical wastewater below the threshold value documented in discharge standard. The stable phenol removal performance in the duration of 900 min demonstrated the stability of flow-through electrode. This work provides a new insight into the electrochemical activation of H2O2 into ·OH for harmless treatment of refractory pollutants.