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

Abstract

ABSTRACT 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.