Fluorine-Free Hydrophobic Nanoscale Zirconium(IV) MOF for the Highly Selective Adsorptive Separation of PFASs from Water

The environmental persistence and structural robustness of per- and polyfluoroalkyl substances (PFASs) have raised serious concerns due to widespread contamination and bioaccumulation in aquatic systems. This necessitates urgent advancement toward developing emerging technology for decontaminating environmental water from diverse amphiphilic PFAS molecules. In this study, we demonstrated a hydrophobicity-modulated, robust Zr(IV)-based porous, nanosized metal–organic framework (MOF) named 1′ for the selective, fast, and recyclable extraction of perfluorooctanoic acid (PFOA) and 1 H,1 H,2 H,2 H -perfluorooctanesulfonic acid (H 4 PFOS) from real environmental water matrices. Hydrophobicity modulation is achieved through the strategic functionalization of the amino-functionalized MOF with long alkyl chains via amido linkages, which enhances nonpolar character (WCA = 130 ± 1°) while preserving the intrinsic porous crystalline architecture of the framework. Additionally, synthesized nanoscale 1′ enables efficient hydrophobic–hydrophobic interaction and hydrogen bonding interaction-based extraction of PFOA and H 4 PFOS species with exceptionally high adsorption capacities of 661.6 and 788.6 mg g –1, along with faster adsorption kinetics (equilibrium time <2 min). Outstanding hassle-free regeneration and reusability of 1′, along with efficient PFOA and H 4 PFOS removal over multiple adsorption–desorption cycles, substantiate its sustainability. Moreover, the selective adsorption of PFOA and H 4 PFOS remained unaffected across varying pH conditions or the excess presence of competing analytes, underscoring the material’s broad-spectrum applicability for decontaminating PFOA and H 4 PFOS in real environmental water matrices. Moreover, a 1′/Chitosan composite sponge was synthesized to demonstrate filtration-based decontamination of PFOA and H 4 PFOS, ensuring its applicability and efficiency for bulk-scale applications. These findings underscore the potential of rational MOF design for extracting broad-spectrum PFASs, even at ultratrace concentrations, offering a robust platform for environmental remediation and regulatory compliance.