Liangdi Jiang,Zhouyang Huang,Jiacan Xu,Liqiu Zhang,Ziwen Du
Selectivity is the key for adsorption or recovery of per- and polyfluoroalkyl substances (PFAS) from aqueous environments. In this study, the fluorinated metal–organic frameworks (MOFs) with different fluorine contents were prepared and investigated to evaluate the selective adsorption of an emerging PFAS, sodium p‑perfluorous nonenoxybenzenesulfonate (OBS). Adsorption of OBS increased with the increasing fluorine content of MOFs, and the best fluorinated MOFs showed an excellent selective adsorption capacity. The influence of various co-existing hydrocarbon substances on OBS adsorption was slight. The adsorption amount of OBS was 15-fold to that of the hydrocarbon surfactants (n-caprylic acid). The selectivity was attributed to the fluorinated structures of MOFs whose oil contact angle was up to 101°, and thus the oleophobicity of fluorinated structures made MOFs repel hydrocarbon compounds. Molecular dynamics simulations and density functional theory calculations indicated that the fluorinated structures were able to capture OBS molecules from the long distances (roughly 1–100 nm) via hydrophobic interaction, and then formed a F–F non-covalent interaction which was highly probable to be driven by a dispersion force to further attract OBS fluorinated tails within shorter distances (less than 3.5 Å). The combination of oleophobic and fluorophilic effects contribute to the exclusive selectivity of fluorinated MOFs for OBS molecule.
In aquatic environments, microplastics (MPs), sulfonamides (SAs), and heavy metals frequently coexist due to their enduring persistence and continual influx. MPs exhibit a notable capacity for adsorbing both SAs and heavy metals, but their coadsorption behavior and the underlying mechanisms remain inadequately understood. This study explores the coadsorption behavior of ten SAs and copper ions (Cu2+) on polyamides (PA) in aqueous solutions. Results reveal that PA possesses an excellent adsorption capacity with synergistic effects for SAs and antagonistic effects for Cu2+. These effects persist under varying pH values, calcium ions, and humic acid. Mechanistic investigations indicate that these joint effects are not driven by the SA–Cu2+ complexation but by changes in PA’s surface properties, functional groups, and weak interactions. Introducing Cu2+ leads to variations in the functional groups at the interaction interface, resulting in an increase negative surface charge of PA. In coadsorption, interaction distances and energies for SAs and Cu2+ are significantly modified, particularly for electrostatic and van der Waals forces, due to enhanced electron transfer. Key SA quantum chemical descriptors (εα and π) correlate with these joint effects. These findings provide a new theoretical foundation for understanding coadsorption of pollutants on MPs.
Shuo Xie,Wenbin Zhang,Yike Han,Xinyan Dong,Wanning Li,Penghui Li,Liyun Kong
The accurate determination of pharmaceuticals and personal care products (PPCPs) in wastewater is crucial for comprehensive environmental risk assessment and human exposure evaluation. Given the complex matrices of aqueous environmental samples, efficient sample preparation remains a critical challenge in analytical procedures. This study presents an ionic liquid-based aqueous two-phase system (IL-ATPS) extraction methodology used as a pretreatment step prior to high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for the simultaneous determination of 38 PPCPs. A mechanistic investigation revealed that target analytes with more hydrogen-bonding sites and higher hydrogen-bond donor (HBD) capacity exhibited enhanced solubility in ILs. In addition, IL anions with stronger hydrogen-bond acceptor (HBA) capacity further improved the solubility of the 38 PPCPs. These findings indicate that hydrogen bonding between analytes and ILs likely played a critical role in the dissolution mechanism. The established IL-salt ATPS extraction method utilized a 15 mL aqueous sample, 0.2 g tetraethylammonium acetate ([N 2222 ][OAc]), and 12 g K 2 HPO 4 , with a 1-minute vortex mixing. Compared with traditional solid phase extraction (SPE), this approach significantly reduced the sample volume from 1 L to 15 mL, avoided the use of volatile organic solvents, simplified the overall processing, and enabled rapid (<15 minutes) pretreatment. The method demonstrated excellent sensitivity with limits of detection (LODs) ranging from 0.00013 to 0.11 ng/mL. Method validation via standard addition experiments demonstrated satisfactory accuracy, yielding recoveries between 74.3 and 129.8 %. Precision was assessed using both intra-day and inter-day measurements. The intra-day relative standard deviations (RSDs) ranged from 0.7 % to 19.9 %, while the inter-day RSDs ranged from 1.4 % to 18.4 %, demonstrating that the method provides consistent and reproducible results under controlled laboratory conditions. These findings underscore the present IL-based ATPS extraction method, followed by HPLC-MS/MS analysis, as an eco-friendly, robust, and scalable approach for PPCPs monitoring in aqueous environmental samples, offering potential applications in environmental monitoring and risk assessment.
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