Bifunctional luminescent iCOF enabling onsite ultrasensitive monitoring and effective removal of perfluorooctane sulfonate in water.

In consideration of the severe hazards of perfluorooctane sulfonate (PFOS) pollution, this study presents a bifunctional luminescent ionic covalent organic framework (iCOF), N⁺-DT-COF, engineered for the simultaneous ultrasensitive detection and highly efficient removal of PFOS in water. The material was synthesized via post-functional modification by grafting quaternary ammonium cationic chains onto a parent spherical DT-COF framework, which was comprehensively confirmed through SEM, XPS, FT-IR, and PXRD analyses. This strategic modification induced a critical photophysical transition that converted the non-emissive DT-COF into a highly fluorescent material by disrupting its inherent π–π stacking. The resulting N⁺-DT-COF functioned as a superior sensor, achieving an ultra-low detection limit of 0.079 ng/L for PFOS via a fluorescence quenching mechanism, with a rapid response within 5 min and exceptional selectivity. Concurrently, it served as a powerful adsorbent, exhibiting a remarkable maximum adsorption capacity of 561.8 mg/g, following pseudo-second-order kinetics. Validation using real Pearl River water samples demonstrated not only high analytical accuracy (102.9–107.4% recovery) and precision (RSDs < 2.5% intra-day, < 3.1% inter-day), but N⁺-DT-COF also achieved complete PFOS removal, underscoring its dual-function capability. This work establishes a promising strategy for the integrated monitoring and remediation of PFOS contamination.