Unique fluorophilic pores engineering within porous aromatic frameworks for trace perfluorooctanoic acid removal

Perfluorooctanoic acid (PFOA), a representative of per/polyfluorinated alkyl substances, has become a persistent water pollutant of widespread concern due to its biological toxicity and refractory property. In this work, we design and synthesize two porous aromatic frameworks (PAF) of PAF-CF₃ and PAF-C₂F₅ using fluorine-containing alkyl based monomers in tetrahedral geometry. Both PAFs exhibit nanosized pores (∼1.0 nm) of high surface areas (over 800 m² g^-1) and good fluorophilicity. Remarkable adsorption capacity (˃740 mg g^-1) and superior efficiency (˃24 g mg^-1 h^-1) are achieved toward the removal of PFOA with 1 μg L^-1 concentration owing to unique C-F···F-C interactions. In particular, PAF-CF₃ and PAF-C₂F₅ are able to reduce the PFOA concentration in water to 37.9 ng L^-1 and 43.3 ng L^-1, below EPA regulations (70 ng L^-1). The reusability and high efficiency give both PAFs a great potential for sewage treatment.