Enhanced electrochemical degradation of perfluorooctanoic acid by ligand-bridged PtII at Pt anodes

Xiaolei Teng; Yumeng Qi; Ruixue Guo; Shengnan Zhang; Junyan Wei; Jamaan S Ajarem; Saleh Maodaa; Ahmed A Allam; Zunyao Wang; Ruijuan Qu

doi:10.1016/j.jhazmat.2023.133008

Enhanced electrochemical degradation of perfluorooctanoic acid by ligand-bridged Pt^II at Pt anodes

J Hazard Mater. 2024 Feb 15:464:133008. doi: 10.1016/j.jhazmat.2023.133008. Epub 2023 Nov 18.

Authors

Affiliations

¹ State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China.
² Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
³ Department of Zoology, Faculty of Science, Beni-suef University, Beni-suef 65211, Egypt.
⁴ State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, Jiangsu, PR China. Electronic address: quruijuan0404@nju.edu.cn.

PMID: 37984143
DOI: 10.1016/j.jhazmat.2023.133008

Abstract

A new mechanism for the electro-oxidation (EO) degradation of perfluorooctanoic acid (PFOA) by Pt anode was reported. Using bridge-based ligand anions (SCN^-, Cl^- and N₃^-) as electrolytes, the degradation effect of PFOA by Pt-EO system was significant. Characterization of the Pt anode, the detection and addition of dissolved platinum ions, and the comparison of Pt with DSA anodes determined that the Pt- ligand complexes resulting from the specific binding of anodically dissolved Pt^II with ligand ions and C₇F₁₅COO^- ((C₇F₁₅-COO)Pt^II-L₃, L = SCN^-, Cl^- and N₃^-) on the electrode surface played a decisive role in the degradation of PFOA. Density functional theory (DFT) calculations showed that inside (C₇F₁₅-COO)Pt^II-L₃ complexes, the electron density of the perfluorocarbon chain (including the F atom) compensated toward the carboxyl group and electrons in the PFOA ion transferred to the Pt^II-Cl₃. Moreover, the (C₇F₁₅-COO)Pt^II-Cl₃, as a whole, was calculated to migrate electrons toward the Pt anode, leading to the formation of PFOA radical (C₇F₁₅-COO•). Finally, with the detection of a series of short chain homologues, the CF₂-unzipping degradation pathway of PFOA was proposed. The newly developed Pt-EO system is not affected by water quality conditions and can directly degrade alcohol eluent of PFOA, which has great potential for treating industrial wastewater contaminated with PFOA.

Keywords: Electro-oxidation; Ligand bridge; Perfluorooctanoic acid; Pt electrode; Pt-ligand complexes.