Highly Efficient Removal of PFCAs by Metal‐Organic Frameworks via Chain‐Length‐Dependent Entrainment Co‐Adsorption Mechanism

Selective adsorption removal of perfluoroalkyl carboxylic acids (PFCAs) in multicomponent system remains a critical challenge, as current studies largely focus on fluorinated adsorbent design or single‐component capacity enhancement, lacking systematic strategy. Here, we report three functionalized Zr‐based metal‐organic frameworks, i.e., acetic acid modified MOF‐808 (MOF‐808‐AA), trifluoroacetic acid modified MOF‐808 (MOF‐808‐TFA), and 5‐fluoroisophthalic acid doped MOF‐808‐AA (F‐MOF‐808‐AA) for targeted capture of C4‐C12 PFCAs. In single‐component system, MOF‐808‐TFA exhibits more efficient adsorption for short‐chain PFCAs (C4‐C7: 605–1141 mg g −1 ), whereas F‐MOF‐808‐AA demonstrates higher adsorption capacity for long‐chain PFCAs (C8‐C12: 1576–2062 mg g −1 ). Remarkably, in mixed‐PFCA system, the cumulative adsorption capacity far exceeds the sum of single‐component saturation capacity, demonstrating synergistic enhancement and robust anti‐competition performance. Mechanistic study reveals that long‐chain PFCA preferentially binds Zr 6 cluster via carboxylate exchange. Subsequent chain‐length‐driven displacement creates a dynamically regulated adsorption interface, and short‐chain PFCA can embed into the hydrophobic pore network through non‐coordinative fluorine–fluorine interaction. A packed bed reactor filled with granular absorbent demonstrates a super stable removal performance for C4‐C12 PFCAs in field application. This work reports a new entrainment adsorption mechanism, where pre‐adsorbed long‐chain PFCA entrains short‐chain PFCA, surpassing conventional adsorption limit and offering a highly efficient strategy for PFCA‐contaminated water remediation.