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

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.

Automated summary

A novel boron-doped diamond (BDD) flow-through cell was used to evaluate the electrochemical oxidation of perfluoroalkyl acids (PFAAs) in landfill leachates. The study found that the oxidation process achieved non-detect levels and >90% degradation for PFOS and PFOA after 2 hours of treatment in all tested leachates; trends of decreasing for certain PFAAs such as PFHpA, PFHxA, and PFHxS, and increasing for others like PFPeA, PFBA, and PFBS were observed; total PFAAs removal ranged from -138.6% to 73.5%.