Multi Capture Site Design in a Bifunctional Zr-MOF for Broad Spectrum and Efficient Removal of Short and Long Chain PFAS

The escalating threat of per and polyfluoroalkyl (PFAS) substances to human health and the ecological environment has intensified the need for advanced porous adsorbents. Herein, we report a series of mono and bifunctionalized MOF 808 materials grafted with fluoroalkyl and amino groups, systematically evaluating the contribution of the trifluoromethylalanine (TFMA) moiety toward broad spectrum PFAS uptake. Batch adsorption experiments reveal exceptional capacities of MOF 808 TFMA for perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA), reaching 1558.3 and 605.4 mg g-1, respectively, with equilibration achieved within 30 minutes. Over 85% removal efficiency was maintained even at trace concentrations, alongside strong anti interference capability. The material retained 81% of its initial efficiency after five regeneration cycles using methanol–ammonia. Combined experimental characterization and density functional theory (DFT) calculations elucidate a multi synergistic site mechanism: amino enabled hydrogen bonding and electrostatic interactions dominate short chain PFAS capture, while fluorophilic and hydrophobic interactions enhance long chain PFAS adsorption. Notably, we identify for the first time an “adsorption trough” for perfluorohexanoic acid (PFHxA), attributed to a pore size–molecular dimension critical matching effect (ΔS° < 0), providing a theoretical early warning for avoiding synergistic failure in adsorbent design. The bifunctional MOF 808 TFMA demonstrates outstanding PFAS removal performance in real wastewater, offering a foundational strategy for the rational design of next generation PFAS adsorbents.