The　presence　of　polyethylene　terephthalate　(PET)　microplastics　(MPs)　in　waters　has　posed　considerable　threats　to　the　environment　and　humans.　In　this　work,　a　heterogeneous　electro-Fenton-activated　persulfate　oxidation　system　with　the　FeS2-modified　carbon　felt　as　the　cathode　(abbreviated　as　EF-SR)　was　proposed　for　the　efficient　degradation　of　PET　MPs.　The　results　showed　that　i)　the　EF-SR　system　removed　91.3　±　0.9　%　of　100　mg/L　PET　after　12　h　at　the　expense　of　trace　loss　(＜　0.07　%)　of　[Fe]　and　that　ii)　dissolved　organics　and　nanoplastics　were　first　formed　and　accumulated　and　then　quickly　consumed　in　the　EF-SR　system.　In　addition　to　the　destruction　of　the　surface　morphology,　considerable　changes　in　the　surface　structure　of　PET　were　noted　after　EF-SR　treatment.　On　top　of　the　emergence　of　the　O-H　bond,　the　ratio　of　C-O/C=O　to　C-C　increased　from　0.25　to　0.35,　proving　the　rupture　of　the　backbone　of　PET　and　the　formation　of　oxygen-containing　groups　on　the　PET　surface.　With　the　verified　involvement　and　contributions　of　SO4•-　and　•OH,　three　possible　paths　were　proposed　to　describe　the　degradation　of　PET　towards　complete　mineralization　through　chain　cleavage　and　oxidation　in　the　EF-SR　system.　©　2024　Elsevier　B.V.