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 TiO2 nanotubes (B, Co-TNT) as the anode and carbon black doped carbon felt (CB-CF) that had a high H2O2 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 Fe2+ 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 center dot OH and SO4 center dot- 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.

Automated summary

A flow-through system was constructed for the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) using boron and cobalt co-doped TiO2 nanotubes (B, Co-TNT) as the anode and carbon black doped carbon felt (CB-CF) as the cathode. The B, Co-TNT anode system showed higher degradation efficiency and lower energy consumption compared to the dimensionally stable anode (DSA) system. The optimal Fe2+ dosage, as well as the effects of initial pH, current intensity, and flow rate, were studied. The mechanisms involved in the degradation of 2,4-D were anodization and Fenton oxidation. The flow-through AO-EF system exhibited stable performance and efficient degradation performance for different contaminants.