Wettability tunable metal organic framework functionalized high internal phase emulsion porous monoliths for fast solid-phase extraction and sensitive analysis of hydrophilic heterocyclic amines

Defective UiO-66/cellulose nanocomposite aerogel for the adsorption of heterocyclic aromatic amines

Heterocyclic aromatic amines (HAAs), arising as chemical derivatives during the high-temperature culinary treatment of proteinaceous comestibles, exhibit notable carcinogenic potential. In this paper, a composite aerogel (AGD-UiO-66) with high-capacity and fast adsorption of HAAs was made with anchoring defective UiO-66 (D-UiO-66) mediated by lauric acid on the backbone of cellulose nanofibers (CNF). AGD-UiO-66 with hierarchical porosity reduced the mass transfer efficiency for the adsorption of HAAs and achieved high adsorption amount (0.84-1.05 μmol/g) and fast adsorption (15 min). The isothermal adsorption model demonstrated that AGD-UiO-66 belonged to a multilayer adsorption mechanism for HAAs. Furthermore, AGD-UiO-66 was successfully used to adsorb 12 HAAs in different food (roasted beef, roasted pork, roasted salmon and marinade) with high recoveries of 94.65%-104.43%. The intrinsic potential of AGD-UiO-66 demonstrated that it could be widely applicable to the adsorption of HAAs in foods.

In-situ growth of metal-organic frameworks on cellulose nanofiber aerogels for rapid adsorption of heterocyclic aromatic amines

Heterocyclic aromatic amines (HAAs) are the main carcinogens produced during thermal processing of protein-rich foods. In this paper, a composite aerogel (TOCNFCa) with a stabilized dual-network structure was prepared via a template for the in-situ synthesis of UiO-66 on cellulose for the adsorption of HAAs in food. The dual-network structure of TOCNFCa provides the composite aerogel with excellent wet strength, maintaining excellent compressive properties. With the in-situ grown UiO-66 content up to 71.89 wt%, the hierarchical porosity endowed TOCNFCa@UiO-66 with the ability to rapidly adsorb HAAs molecules with high capacity (1.44-5.82 μmol/g). Based on excellent thermal stability, adsorption capacity and anti-interference, TOCNFCa@UiO-66 achieved satisfactory recoveries of HAAs in the boiled marinade, which is faster and more economical than the conventional SPE method. Moreover, TOCNFCa@UiO-66 could maintain 84.55 % of the initial adsorption capacity after 5 times of reuse.

Controlled synthesis of sulfhydryl-dendritic mesoporous silica nanospheres for ultrafast extraction and sensitive analysis of organochlorine herbicides containing amide groups

The distinctive morphology of dendritic mesoporous silica nanoparticles (DMSN) has recently attracted considerable attention in scientific community. However, synthesis of DMSN with well-defined structure and uniform size for ultrafast extraction of trace herbicide residues from environmental and food samples remains to be a compelling challenge. In this study, sulfhydryl functionalized dendritic mesoporous silica (SH-DMSN) was synthesized and the SH-DMSN showcases monodisperse microspheres with flower shape and precisely tailored and controllable pore sizes. This distinctive structural configuration accelerates mass transfer within the silica layer, resulting in heightened adsorption efficiencies. Furthermore, the particle sizes (455, 765, and 808) of the adsorbent can be meticulously fine-tuned by introducing distinct templates. Specifically, when the particle size is 765 nm, the optimized SH-DMSN exhibits a substantial specific surface area (691.32 m²/g), outstanding adsorption efficiencies (>90 %), remarkably swift adsorption and desorption kinetics (2 min and 3 min, respectively), and exceptional stability. The superior adsorption capabilities of this novel adsorbent, ranging from 481.65 to 1021.7 µg/g for organochlorine herbicides containing amide groups, can be attributed to the interplay of S-π interactions, halogen bonding, and electrostatic attraction interaction. These interactions involve the lone pair electrons of sulfhydryl and silanol groups with the π-electrons, halogen atoms and amide groups in herbicide molecules. This study not only offers a new perspective on advancing the practical utilization of dendritic mesoporous silica but also provides a pragmatic strategy for the separation and analysis of herbicides in diverse sample matrices.

Covalent organic frameworks based hierarchical porous hybrid monolithic capillary: Synthesis, characterization, and applications in trace metals analysis

The preparation of hierarchical porous monolithic column with high covalent organic frameworks (COF) loading and micropores accessibility is challenging due to the easy aggregability and sedimentation of COFs. Herein, a novel strategy based on high internal phase emulsion (HIPE) polymerization was proposed for preparing COF hybrid capillary monolithic column with hierarchical porosity. COFs with different frameworks including imine COFs (COF-OMe, COF-F and COF-SH), triazine COF (CTF-1) and boron-based COF (COF-5) were selected to investigate the universality of the preparation strategy. The presence of COF in the monolithic capillary was confirmed by scanning electron microscope, X-ray diffraction and fourier transform infrared spectroscopy. Nitrogen adsorption/desorption experiments and thermogravimetric analysis showed that the prepared COF hybrid monolithic capillary exhibited high COF loading (e.g., 28.7% for COF-SH) and accessibility (e.g., 98.5% for COF-SH), mainly due to the thin walls of void-window structures originated from polymerization of HIPE. The successful preparation of water-stable COF-F, COF-OMe, COF-SH and CTF-1 hybrid monolithic columns demonstrated the proposed synthesis strategy is universal to water-stable COF without tedious optimization of dispersion system, effectively avoiding the sedimentation of COF in pre-polymerization solution. Then, the sulfhydryl-modified COF hybrid polymer (poly(COF-SH-HIPE)) monolithic column was evaluated for the extraction of heavy metal ions, and a method based on poly(COF-SH-HIPE) monolithic capillary microextraction on-line coupled with inductively coupled plasma mass spectrometry detection was developed for analysis of trace Cd, Hg and Pb in human fluid samples.

Magnetic tubular nickel@silica-graphene nanocomposites with high preconcentration capacity for organothiophosphate pesticide removal in environmental water: Fabrication, magnetic solid-phase extraction, and trace detection

Organothiophosphate pesticides (OPPs) are the most common water contaminants, significantly endangering human health and bringing serious public safety issues. Thus, developing effective technologies for the removal or trace detection of OPPs from water is urgent. Herein, a novel graphene-based silica-coated core-shell tubular magnetic nanocomposite (Ni@SiO₂-G) was fabricated for the first time and used for the efficient magnetic solid-phase extraction (MSPE) of the OPPs chlorpyrifos, diazinon, and fenitrothion from environmental water. The experimental factors affecting extraction efficiency such as adsorbent dosage, extraction time, desorption solvent, desorption mode, desorption time, and adsorbent type were evaluated. The synthesized Ni@SiO₂-G nanocomposites showed a higher preconcentration capacity than the Ni nanotubes, Ni@SiO₂ nanotubes, and graphene. Under the optimized conditions, 5 mg of tubular nano-adsorbent displayed good linearity within the range of 0.1-1 μg·mL^-1, low limits of detection (0.04-0.25 pg·mL^-1), low limits of quantification (0.132-0.834 pg·mL^-1), good reusability (n = 5; relative standard deviations between 1.46% and 9.65%), low dosage (5 mg), and low real detection concentration (< 3.0 ng·mL^-1). Moreover, the possible interaction mechanism was investigated by density functional theory calculation. Results showed that Ni@SiO₂-G was a potential magnetic material for the preconcentration and extraction of formed OPPs at ultra-trace levels from environmental water.

Porous aromatic frameworks with high Pd nanoparticles loading as efficient catalysts for the Suzuki coupling reaction

The development of efficient and recyclable heterogeneous Pd catalysts is an area of continuing attention due to their critical applications in organic synthesis and pharmaceutical production. In this study, two novel heterogeneous catalysts Pd@PAF-182 and Pd@PAF-183 were prepared by the immobilization/NaBH₄ reduction of PdCl₄^2- on hydrophilic cationic porous aromatic frameworks (PAF-182 and PAF-183), which were synthesized via a Yamamoto-type Ullmann coupling reaction from the corresponding aryl quaternary phosphonium salt monomer. Characterization by powder X-ray diffraction (PXRD), solid-state Cross-Polarization Magic-Angle-Spinning Nuclear Magnetic Resonance (CP/MAS NMR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) established the structures of the as-prepared catalysts. Inductively coupled plasma atomic emission spectrometry (ICP-AES) detection showed that the loading of Pd nanoparticles (Pd NPs) were 29.4 wt% for Pd@PAF-182 and 37.5 wt% for Pd@PAF-183, much higher than those of similar porous materials. Evaluation of the catalytic activity of the Pd@PAFs using Suzuki coupling as the model reaction demonstrated that as little as 0.12 mol% of Pd NPs could catalyze the Suzuki coupling with high efficiency, achieving yields up to 99% at 80 °C in 8 h. Recycling experiments also suggested that Pd@PAF-182 and Pd@PAF-183 maintained high catalytic activity with negligible leaching of Pd NPs after five cycles.

Magnetic phenolic resin core-shell structure derived carbon microspheres for ultrafast magnetic solid-phase extraction of triazine herbicides

In this study, monodisperse magnetic carbon microspheres were successfully synthesized through the carbonization of phenolic resin encapsulated Fe₃ O₄ core-shell structures. The magnetic carbon microspheres showed high performance in ultrafast extraction and separation of trace triazine herbicides from environmental water samples. Under optimized conditions, both the adsorption and desorption processes could be achieved in 2 min, and the maximum adsorption capacity for simazine and prometryn were 387.6 and 448.5 μg/g. Coupled with HPLC-UV detection technology, the detection limit of triazine herbicides was in the range of 0.30-0.41 ng/mL. The mean recoveries ranged from 81.44 to 91.03% with relative standard deviations lower than 7.47%. The excellent magnetic solid phase extraction performance indicates that magnetic carbon microspheres are promising candidate adsorbent for the fast analysis of environmental contaminants. This article is protected by copyright. All rights reserved.