Electrochemical oxidation of PFOA and PFOS in landfill leachates at low and highly boron-doped diamond electrodes

Mattia Pierpaoli; Małgorzata Szopińska; Barbara K Wilk; Michał Sobaszek; Aneta Łuczkiewicz; Robert Bogdanowicz; Sylwia Fudala-Książek

doi:10.1016/j.jhazmat.2020.123606

Electrochemical oxidation of PFOA and PFOS in landfill leachates at low and highly boron-doped diamond electrodes

J Hazard Mater. 2021 Feb 5:403:123606. doi: 10.1016/j.jhazmat.2020.123606. Epub 2020 Aug 4.

Authors

Mattia Pierpaoli¹, Małgorzata Szopińska², Barbara K Wilk², Michał Sobaszek³, Aneta Łuczkiewicz², Robert Bogdanowicz³, Sylwia Fudala-Książek⁴

Affiliations

¹ Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunication and Informatics, Gdańsk University of Technology, Gdańsk 80-233, Poland. Electronic address: mattia.pierpaoli@pg.edu.pl.
² Department of Water and Wastewater Technology, Faculty of Civil and Environmental Engineering, Gdańsk University of Technology, Gdańsk 80-233, Poland.
³ Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunication and Informatics, Gdańsk University of Technology, Gdańsk 80-233, Poland.
⁴ Department of Sanitary Engineering, Faculty of Civil and Environmental Engineering, Gdańsk University of Technology, Gdańsk 80-233, Poland.

PMID: 33264854
DOI: 10.1016/j.jhazmat.2020.123606

Abstract

Polyfluorinated alkyl substances (PFASs) may reach landfill leachates (LLs) due to improper waste management. In this study perfluorooctanoate (PFOA) and perfluorooctane sulphonate (PFOS) were used as representatives of PFASs in the decomposition on boron-doped diamond electrodes (BDDs) with high (10k ppm) and low (0.5k ppm) boron doping concentrations. The result shows that although better COD removal efficacies are obtained on the low-doped BDD (59 % after 8 h), the decomposition rate of PFOA and PFOS was not affected by boron doping. In LLs, at the current density of 75 mA/cm², averaged removal efficiencies of 80 % and 78 % were achieved for PFOA and PFOS, respectively. But besides concentration of mother compounds, the presence of intermediates during electrolysis should be monitored. After 8 h of LL electrolysis, the presence of long-chain degradates C₆F₁₃ and C₆F₁₃COO^- was still observed only in 10k BDD-PFOA assays, while during 0.5k assays C₆F₁₃ and C₆F₁₃COO^- form more intesively at the beginning of the process. This indirectly confirms the more intensive generation of perfluoroalkoxy and hydroxyl radicals and higher susceptibility to electrolysis of PFOA's long-chain intermediates on 0.5k BDD. This is the first study reporting BDD-electrolysis as promising in PFAS removal from the complex matrix of LLs, despite the oxidation of competing LLs components.

Keywords: Advanced oxidation process; BDD; Degradation efficacy; Industrial wastewater; Micropollution; PFAS.

Publication types

Research Support, Non-U.S. Gov't