Magnetically assembled electrodes based on Pt, RuO2-IrO2-TiO2 and Sb-SnO2 for electrochemical oxidation of wastewater featured by fluctuant Cl- concentration

• Published in: Journal of hazardous materials Vol. 421; p. 126803
• Main Authors: Zhang, Yuanyuan, Zhang, Cuiping, Shao, Dan, Xu, Hao, Rao, Yongfang, Tan, Guoqiang, Yan, Wei
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.01.2022
• Subjects: Anode; Chlorine; Electrochemistry; Persistent organic pollutant; Wastewater treatment; Persistent organic pollutant; Electrochemistry; Anode; Chlorine; Wastewater treatment
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.126803

Magnetically assembled electrode (MAE) flexibly attracts magnetic particles (auxiliary electrodes, AEs) on a main electrode (ME) by the magnetic force, where the role of ME is always ignored. In this study, Ti/Pt, Ti/RuO2-IrO2-TiO2 and Ti/Sb-SnO2 were selected as the ME for comparison in treating synthetic wastewater (acid red G or phenol) with variable Cl- content. The effects of ME type, loading amount of Fe3O4/Sb-SnO2 AEs, and Cl- concentration were investigated, followed by varied electrochemical characterizations. Results show that AEs played a vital role in electrode activity and selectivity, and MEs also exerted an unignorable influence on the performance of the MAEs. Among the three MEs, Ti/RuO2-IrO2-TiO2 has the best OER/CER ability, activating more extra active sites with same AEs loading amount, leading to higher organics degradation efficiency under chlorine-free condition. However, this MAE is featured by the noticeable accumulation of intermediate products under chlorine-free condition even if 0.3 g·cm−2 of AEs are loaded. All electrodes’ performances were enhanced in the presence of Cl-. With high concentration chloride (0.5 M NaCl), the accumulation of intermediate products was reduced significantly, especially on Ti/RuO2-IrO2-TiO2 based MAE, and no chlorinated compound was identified. Finally, the structure-activity relationships of these MAEs were proposed. [Display omitted] •A new anode architecture was organized by magnetic force.•Main electrodes with different OER/CER activity were compared.•Magnetic particles could effectively increase the less accessible active sites.•The structure-activity relationships under variable Cl- content were discussed.