Mechanochemically Synthesized Covalent Organic Framework Effectively Captures PFAS Contaminants

Abstract

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants that pose significant health risks, prompting urgent efforts to develop effective removal methods and adsorbers. Covalent organic frameworks (COFs) are metal-free adsorbers with high stability and tunable porosity. A highly crystalline COF is synthesised mechanochemically using 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 1,3,5-triformylbenzene (TFB). The formation dynamics are monitored in real time with time-resolved in situ synchrotron X-ray diffraction. The TAPB-TFB COF demonstrates good efficiency in eliminating PFAS from water. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are effectively extracted, and most of the adsorption occurred within the first 10 min. Additionally, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and DFT calculations are employed to elucidate the molecular interactions between PFAS and the COF framework. The rapid and efficient removal of PFAS makes TAPB-TFB COF a promising material for water treatment applications.