Enhanced degradation of 2,4-dichlorophenoxyacetic acid by electro-fenton in flow-through system using B, Co-TNT anode

A flow-through system was constructed for 2,4-dichlorophenoxyacetic acid (2,4-D) degradation for the first time using efficient boron and cobalt co-doped TiO 2 nanotubes (B, Co-TNT) as the anode and carbon black doped carbon felt (CB-CF) that had a high H 2 O 2 yield as the cathode. Compared with dimensionally stable anode (DSA), whether in anodic oxidation (AO) or AO-electro-Fenton (EF) system, 2,4-D degradation in B, Co-TNT anode system was more efficient accompanying with a lower energy consumption (Ec). Different operating parameters including applied current density, initial pH and flow rate were explored, supporting that the optimal Fe 2+ dosage was 0.5 mM while decreasing the initial pH and increasing the current intensity and flow rate were beneficial to 2,4-D removal. In this AO-EF system, the involved mechanisms for 2,4-D degradation were anodization and Fenton oxidation, possessing the comprehensive effect of • OH and SO 4 •- with their contribution of 92.7% and 4.8%, respectively. This flow-through AO-EF system performed a stable performance, and an efficient degradation performance with low Ec (5.8–29.5 kWh (kg TOC) −1 ) was obtained for different kinds of contaminants (methylene blue, phenol, p -nitrophenol and sulfamethazine). Therefore, B, Co-TNT anode coupled with CB-CF cathode in flow-through system was effective for contaminants degradation.