Synergy of the Structure and Interface in Mesoporous UiO-66-F4 3D Chitosan Aerogels for Precise and Selective Identification of Per- and Polyfluoroalkyl Substances

Abstract

Understanding the role of pore architecture and interfacial interactions in Per- and polyfluoroalkyl substances (PFAS) separation and analysis is essential for the rational design of high-performance fluorinated porous adsorbents. In this study, three fluorinated metal−organic framework materials (meso-UiO-66-F4) with tunable mesopore volume were synthesized and incorporated into three-dimensional chitosan aerogels (meso-UiO-66-F4/chitosan aerogel) to construct recyclable adsorbents of monolithic solid-phase extraction (MSPE) for direct immersion solid-phase extraction (DI-SPE), which was applied to selectively enrich 12 PFAS. The adsorption behavior exhibited a clear dependence on the relationship between mesoporous structure and PFAS chain length. The adsorption mechanisms of representative short-chain PFHxA and long-chain PFOA were further investigated by density functional theory (DFT) calculations. The optimized meso-UiO-66-F4/chitosan aerogel exhibited efficient extraction capability toward twelve PFAS with excellent recyclability; it combined liquid chromatography-tandem mass spectrometry (LC-MS/MS) to achieve excellent precision, wide linear ranges of 0.09−200,000 ng L−1, high linearity (R2 = 0.9925−0.9999), and low detection limits of 0.03−1.02 ng L−1. This study provided new insights into the relationship between pore accessibility, molecular confinement, and interfacial affinity, offering a rational strategy for designing reusable fluorinated porous adsorbents for enrichment and determination of trace PFAS from various environmental samples.