Engineering zirconium-based MOFs for selective adsorption of estrogenic contaminants and the application in...

Rational regulation of interfacial chemistry and pore architecture in metal-organic frameworks (MOFs) is critical for the selective adsorption of structurally similar organic contaminants in complex matrices. Herein, a series of zirconium-based UiO-X-Y-Z% frameworks (X denotes 66/67/68, Y represents amino, hydroxyl and carboxyl groups, while Z indicates the substitution ratio) was systematically engineered by independently modulating linker length, functional group chemistry, and amino functionalization density to elucidate structure-property relationships toward five representative estrogenic pollutants (bisphenol A, p-tert-butylphenol, 4-pentylphenol, 4-nonylphenol, and hexestrol). The adsorption performance exhibited a non-monotonic dependence on amino functionalization density, with UiO-67-NH₂-25% exhibited the highest adsorption capacity among the investigated materials under the conditions of this study. The results demonstrate that selective adsorption is governed not simply by pore enlargement or increased functional group loading, but by the cooperative balance among pore accessibility, interfacial polarity, and active-site exposure. Spectroscopic characterization combined with molecular docking and density functional theory calculations revealed that selective adsorption originates from the synergistic coupling of pore-molecule size matching, directional hydrogen bonding, hydrophobic partitioning, and π-π stacking interactions. For practical application, UiO-67-NH₂-50% was integrated into an electrospun solid-phase microextraction Arrow platform, exhibiting stable extraction performance over 200 extraction-desorption cycles and enhanced matrix resistance. Coupled with HPLC-UV detection, the developed method enabled ultra-trace determination of multiple estrogenic pollutants in milk and pork matrices with limits of detection of 0.003-0.01 μg L^-1. This work establishes a mechanistically guided framework for selective adsorption regulation in MOFs and demonstrates the feasibility of polarity-balanced interfacial engineering for contaminant enrichment in complex food matrices.