Study on selective adsorption of organic pollutants in environmental water samples by solid-phase microextraction based on MOF-derived coatings

A novel multifunctional coating strategy was developed through electrodeposition of Co(OH)₂ onto NiTi fibers, followed by <i>in situ</i> transformation into Zeolitic Imidazolate Framework-67(ZIF-67), and subsequent pyrolytic conversion under varied thermal conditions to yield three types of ZIF-67-derived coatings: (1) ZIF-67-Co₃O₄, (2) ZIF-67-nitrogen-doped carbon (ZIF-67-NC), and (3) ZIF-67-carbon (ZIF-67-C). The extraction selectivity of these coatings was systematically evaluated using HPLC-UV analysis against typical organic pollutants, including chlorinated pesticides (CPs), phthalate esters (PAEs), ultraviolet filters (UVFs), and polycyclic aromatic hydrocarbons (PAHs). Results demonstrated that the tailored pyrolytic treatments produced Co-based ZIF-67 derivatives with unique structural characteristics and selective adsorption properties: (i) ZIF-67-C exhibited superior specificity for PAHs adsorption, (ii) ZIF-67-NC demonstrated enhanced selectivity for UVFs extraction, and (iii) ZIF-67-Co₃O₄ displayed dual functionality for both PAHs and UVFs removal. This work not only elucidates the structure-property correlations in ZIF-67-based composites but also significantly expands the applicability of NiTi fibers in solid-phase microextraction (SPME) technology for environmental detection.