Redox-active rGO-nZVI nanohybrid-catalyzed chain shortening of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS)
Arvid Masud, Mary Grace E. Guardian, Steven C. Travis, Nita G. Chavez Soria, Mourin Jarin, Diana S. Aga, Nirupam Aich
Abstract
Per- and polyfluoroalkyl substances (PFASs) are exceptionally stable chemicals due to their strong CF bonds. Nanoscale zero-valent iron (nZVI) particles have the potential to remove and degrade PFASs through redox activity. In this study, we deposited nZVI onto two-dimensional reduced graphene oxide (rGO) nanosheets and tested these synthesized rGO-nZVI nanohybrid (NH) for the treatment of a mixture of short- and long-chain PFASs in water with and without H2O2. All PFASs were removed at a higher efficiency by the rGO-nZVI NH than by the parent materials rGO and nZVI. Notably, the long-chain PFASs were removed at a faster rate than the short-chain PFASs. After a 10 min exposure to the rGO-nZVI NH without H2O2, the long-chain PFASs (perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)) were removed by 85 % and 39 %, respectively, while short-chain PFASs (perfluoropentane sulfonic acid and perfluoropentanoic acid) were removed by 19 % and 18 %, respectively. The addition of H2O2 enhanced the PFAS treatment performance by 10–18 %, which can be attributed to the generation of reactive oxygen species by the rGO-nZVI NH. Liquid chromatography high-resolution mass spectrometry analysis confirmed the formation of unique shorter chain and partially defluorinated PFAS-Fe complexes from both PFOS and PFOA.