Surfactant solubilization enhanced electrochemical degradation of a long-chain perfluoroalkyl substance: Applicability analysis

In environmental settings, perfluorinated compounds are characterized by low concentrations and heterogeneous distributions, which reduce their mass transfer efficiency, rendering conventional treatment technologies largely ineffective. This study examines perfluorododecanoic acid (PFDoDA) as a representative perfluorinated compound, employing solubilizing agents such as Tween80, sodium lauryl sulfate (SLS), and cocamidopropyl betaine to investigate the transfer characteristics and mechanisms of PFDoDA from non-aqueous to aqueous phases. SLS demonstrated the highest efficacy, enhancing the solubility to 2.684 mg/L, an increase by a factor of 6.8. Mechanistically, PFDoDA is solubilized within the micellar core and palisade layer of SLS. The electrocatalytic oxidation process effectively degrades the PFDoDA-rich solubilized solution. The electro-catalytic oxidation system achieved a removal rate exceeding 99 % for PFDoDA over five cycles. Radical quenching experiments and electron paramagnetic resonance (EPR) analysis identified the predominant role of superoxide anions, effectively removing PFDoDA with the assistance of hydroxyl radicals, singlet oxygen and sulfate radical. The degradation pathways of major intermediate products of PFDoDA and solvents were proposed, along with a toxicity assessment. This research is the first to report the combination of surfactants with electro-catalytic oxidation as a promising approach for the removal of perfluorinated compounds.