Perfluorooctanoic acid (PFOA) substitutes such as hexafluoropropylene oxide dimer acid (GenX) and hexafluoropropylene oxide trimer acid (HFPO-TA) are toxic as environmental contaminants, and efficient adsorbents are required to remove them from waters. In this study, the novel cationic covalent organic framework (COF) was developed via an imine condensation reaction for efficient removal of GenX and HFPO-TA from aqueous solution. The prepared COFs exhibited a 2D ordering hexagonal structure with AA stacking and two classes of pores (mesopore and micropore). The introduction of quaternary ammonium on COF exhibited little effect on its morphology and crystal structure. The cationic COF with quaternary ammonium showed high adsorption capacity for GenX (2.06 mmol/g) and HFPO-TA (2.16 mmol/g), more efficient than conventional activated carbons and resins. The effects of pH and natural organic matter on the removal efficiency of GenX and HFPO-TA on COF were also investigated. Interestingly, the previously adsorbed GenX on the cationic COF was replaced by the longer-chain HFPO-TA, and the underlying competitive mechanism was further clarified by performing a density functional theory calculation. This study highlights the exceptional potential of COFs through topology structural design for the efficient removal of per- and polyfluoroalkyl substances from aqueous solution.

全氟辛酸（PFOA）替代品，例如六氟环氧丙烷二聚酸（GenX）和六氟环氧丙烷三聚酸（HFPO-TA），作为环境污染物有毒，因此需要有效的吸附剂将其从水中去除。在这项研究中，新型阳离子共价有机骨架（COF）通过亚胺缩合反应，可从水溶液中有效去除GenX和HFPO-TA。制备的COF表现出具有AA堆积和两类孔（中孔和微孔）的二维有序六边形结构。在COF上引入季铵盐对其形态和晶体结构影响很小。带有季铵盐的阳离子COF对GenX（2.06 mmol / g）和HFPO-TA（2.16 mmol / g）表现出高吸附能力，比常规活性炭和树脂更有效。还研究了pH和天然有机物对GenX和HFPO-TA对COF的去除效率的影响。有趣的是，原来在阳离子COF上吸附的GenX被长链HFPO-TA取代，并通过进行密度泛函理论计算进一步阐明了潜在的竞争机制。这项研究通过拓扑结构设计突出了COF的巨大潜力，可以有效地从水溶液中去除过氟和多氟烷基物质。