High-efficiency electro-Fenton synergistic electrocoagulation for enhanced removal of refractory organic pollutants

• Published in: Journal of environmental management Vol. 370; p. 122873
• Main Authors: Liu, Kang, Xu, Tao, Hu, Simeng, Zhuang, Xiaojie, Zhou, Yihui, Lei, Xiping, Zhang, Xueyuan, Xie, Lianwu
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2024
• Subjects: Electro-Fenton; Electrocoagulation; Energy efficiency analysis; Refractory organic pollutants; Removal mechanism; Electro-Fenton; Removal mechanism; Electrocoagulation; Refractory organic pollutants; Energy efficiency analysis
• ISSN: 0301-4797; 1095-8630; 1095-8630
• DOI: 10.1016/j.jenvman.2024.122873

The persistence and stability of refractory organic compounds such as dyes in water bodies cause serious toxicity to humans. The present study provides an in-depth investigation into the evolution law of electro-Fenton (EF) oxidation to in situ electrocoagulation (EC) process and its mechanism for highly efficient removal of refractory organic pollutants. A comprehensive evaluation of the energy efficiency by EC, EF (constant pH = 3) and electrocatalytic oxidation (EO) processes under the same research levels was conducted. The results showed that in the EF-EC mode, the removal efficiency of Rhodamine B (RhB) was enhanced by 33.41% compared to the EC system. Additionally, electrode consumption is 52.9% of the EF system, and current efficiency was improved by 272.98% compared to the EO system. Hydroxyl radical (·OH) and polynuclear species (Fe(b)) are the main species to remove refractory organics and intermediates. Unlike the synergistic effect of ·OH homogeneous oxidation and electrocoagulation in the EF-EC process, the ·OH produced in the EO process mainly undergoes heterogeneous oxidation at the electrode interface. The formed iron oxides were mainly Fe2O3 and ɑ-FeOOH. Density functional theory calculations and liquid chromatograph-mass spectrometer analysis indicated that the degradation of RhB mainly included deethylation, deamination, degradation, ring-opening and mineralization reactions. This study provides a valuable reference for related research in the field of environmental electrochemical remediation. [Display omitted] •Fe electrode EF-EC system could effectively remove refractory organic matter.•The evolution mechanism of EF-EC system were proposed.•EF-EC system could effectively improve the Re(RhB) and current efficiency.•·OH and Fe(b) are the main species to remove refractory organics and intermediates.•The homogeneous and heterogeneous oxidation mechanisms of ·OH were examined.