A flow-through cell for the electrochemical oxidation of perfluoroalkyl substances in landfill leachates

October 1, 2021 - Author: Vanessa Y. Maldonado, Greg M. Landis, Mary Ensch, Michael F. Becker, Suzanne E.Witt, and Cory A.Rusinek

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Highlights

  • A novel boron-doped diamond (BDD) flow-through cell was used for electrochemical treatment of landfill leachates.
  • Individual PFAAs concentrations were in the range of 102 − 104 ng/L in six landfill leachates treated.
  • Non-detect levels for PFOS and removal > 97 % for PFOA were reached for all leachates treated.
  • The flow-through cell allows for a lower energy consumption than the traditional parallel-plate cell.

Abstract

A novel boron-doped diamond (BDD) flow-through cell was used to evaluate the electrochemical oxidation of perfluoroalkyl acids (PFAAs) in landfill leachates. Six different leachates with a concentration of individual PFAAs in the range of 102 − 104 ng/L were treated. The performance of the flow-through cell was assessed and compared with synthetic solutions for the oxidation of two representative PFAAs: perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). Subsequently, the effect of current density and the variability of leachates composition was investigated for the electrochemical oxidation of PFAAs in real landfill leachates. Non-detect levels and >90% degradation was reached for PFOS and PFOA after 2 h of treatment for all leachates tested. Decreasing trends for perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), and perfluorohexanesulphonic acid (PFHxS), and increasing trends for perfluoropentanoic (PFPeA), perfluorobutanoic (PFBA), and perfluorobutanesulphonic acid (PFBS) were observed. The total PFAAs removal ranged from −138.6 to 73.5%. Correlations between the composition of the leachates and PFAAs removal percentages were determined. Overall, the results show the potential of electrochemical oxidation to oxidize PFAAs present in high strength water such as landfill leachates.

Tags: pfas research

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