A novel enhanced defluorination of perfluorooctanoic acids by surfactant-assisted ultrasound coupling persulfate

A novel enhanced defluorination of perfluorooctanoic acids (PFOA) by surfactant-assisted ultrasound (US) coupling persulfate (PS) was proposed in this study. Instead of adding the surfactant into the PFOA solution directly, the promoted defluorination was obtained by adding the surfactant to the US bath outside of the PFOA reactor. In this situation, the effects of the critical micelle concentration (CMC), concentration and type of the surfactant, the US frequency and the pH of the US bath liquid on the PFOA defluorination were investigated. The results demonstrated that the PFOA defluorination at low-frequency levels (25 kHz-59 kHz) was facilitated by raising US frequency. Besides, the addition of three surfactants (Triton X-100, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB)) all increased the PFOA defluorination by Triton X-100 > CTAB > SDS, which is opposed to their CMC (Triton X-100: 0.28 mM

Automated summary

A novel surfactant-assisted ultrasound coupling persulfate method was proposed for the enhanced defluorination of perfluorooctanoic acids (PFOA). Instead of adding the surfactant directly into the PFOA solution, the surfactant was added to the ultrasound bath outside of the PFOA reactor. The effects of critical micelle concentration, surfactant concentration and type, ultrasound frequency, and pH of the ultrasound bath liquid on PFOA defluorination were investigated, and it was found that low-frequency ultrasound levels facilitated the defluorination of PFOA.