Highly efficient degradation of perfluoroalkyl substances (PFAS) by a novel polytetrafluoroetylene piezocatalyst

Perfluoroalkyl substances (PFAS) are environmentally persistent, bioaccumulative and toxic pollutants. However, thorough degradation of PFAS remains exceptionally difficult due to the high dissociation energy of the C-F bond. Here, we report a viable strategy to markedly degrade PFAS completely by capitalizing on a harmless polytetrafluoroetylene (PTFE) as a piezocatalyst. Remarkably, perfluorooctanoic acid (PFOA), as one of the widely used PFAS, was almost completely removed with a degradation rate of 93.4 % and a defluorination rate of 91.5 % by the ultrasound excitation of PTFE for 1 h. On the basis of the intermediate analysis, we proposed an oxidation mechanism for the piezocatalytic PFOA degradation. Furthermore, this strategy was also efficient for the degradation of perfluoroheptanoic acid (PFNA), perfluorooctane sulfonate (PFOS) and hexafluoropropylene oxide dimer acid (Gen-X), implying its effectiveness to remediate water containing multiple PFAS. Impressively, due to the diverse energy gap between HOMO and LUMO energy of various PFAS, the degradation reaction kinetics of different PFAS are of significant difference. This study provides the deep insight into the piezocatalytic technique for the remediation of persistent and disparate PFAS.