Structural behaviour of graphene and silver functionalized graphene oxide loaded with perfluorinated compounds during thermal heating

Perfluorinated substances (PFAS) are environmental contaminants that are difficult to break down chemically, thermally, and biologically. Adsorption is the most effective and affordable way to remove PFAS from aquatic environments. Graphene oxide (GO) has gained popularity in water filtration because of its aqueous dispersibility, reactivity, high stability, flexibility, and low cost. Adsorption experiments, high performance liquid chromatography, in situ powder diffraction data, and thermal analysis were used in this study to evaluate PFAS removal and study the real-time evolution of graphene oxide (GO) before and after Ag functionalization, perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS) loading. Diffraction data revealed structural changes, and the interaction of PFOA and PFOS with GO interlayers caused a (001) peak shift to higher 2θ values, indicating their presence in the structure. At 150°C, functional groups were ejected, structural defects occurred, and the GO characteristic peak (001) shifted. At 350°C, the (001) reflection disappeared and the (002) peak intensity increased, suggesting that GO was converted to reduced graphene oxide (rGO). Silver loading in GO (AgGO) was confirmed by new reflections attributed to Ag nanoparticles and a decrease in dhkl values. The degradation of PFOA and PFOS molecules occurred between 375 and 400°C.