Surfactant Pyrolysis-Guided in Situ Fabrication of Primary Amine-Rich Ordered Mesoporous Phenolic Resin Displaying Efficient Heavy Metal Removal

Molecularly imprinted resin modified with ionic liquid for dispersive filter extraction and determination of perfluoroalkyl acids in eggs

Perfluoroalkyl acids (PFAAs) are emerging pollutants that endangers food safety. Developing methods for the selective determination of trace PFAAs in complex samples remains challenging. Herein, an ionic liquid modified porous imprinted phenolic resin-dispersive filter extraction-liquid chromatography-tandem mass spectrometry (IL-PIPR-DFE-LC-MS/MS) method was developed for the determination of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in eggs. The new IL-PIPR adsorbent was prepared at room temperature, which avoids the disorder and instability of the template at high temperatures. The imprinting factor of IL-PIPR for PFOA and PFOS exceeded 7.3. DFE, combined with IL-PIPR (15 mg), was used to extract PFOA and PFOS from eggs within 15 min. The established method exhibits low limits of detection (0.01-0.02 ng/g) and high recoveries (84.7%-104.7%), which surpass those of previously reported methods. This work offers a new approach to explore advanced imprinted adsorbents for PFAAs, efficient sample pretreatment technique, and analytical method for pollutants in foods.

Postsynthetic Modification of Core-Shell Magnetic Covalent Organic Frameworks for the Selective Removal of Mercury

Core-shell magnetic covalent organic framework (COF) materials were prepared, followed by shell material functionalization with different organic ligands, including thiosemicarbazide, through a postsynthetic modification approach. The structures of the prepared samples were characterized with various techniques, including powder X-ray diffraction (PXRD), Brunauer-Emmett-Teller (BET) method, thermogravimetric analysis (TGA), photoinduced force microscopy (PiFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and solid ¹³C NMR. PXRD and BET studies revealed that the crystalline and porous nature of the functionalized COFs was well maintained after three steps of postsynthetic modification. On the other hand, solid ¹³C NMR, TGA, and PiFM analyses confirmed the successful functionalization of COF materials with good covalent linkage connectivity. The use of the resulting functionalized magnetic COF for selective and ultrafast adsorption of Hg(II) has been investigated. The observations displayed rapid kinetics with adsorption dynamics conforming to the quasi-second-order kinetic model and the Langmuir adsorption model. Furthermore, this prepared crystalline magnetic material demonstrated a high Langmuir Hg(II) uptake capacity, reaching equilibrium in only 5 min. Thermodynamic calculations proved that the adsorption process is endothermic and spontaneous.

Adsorption of heavy metal onto biomass-derived activated carbon: review

Due to the rapid development of the social economy and the massive increase in population, human beings continue to undertake processing, and commercial manufacturing activities of heavy metals, which has caused serious damage to the environment and human health. Heavy metals lead to serious environmental problems such as soil contamination and water pollution. Human health and the living environment are closely affected by the handling of heavy metals. Researchers must find several simple, economical and practical methods to adsorb heavy metals. Adsorption technology has been recognized as an efficient and economic strategy, exhibiting the advantages of recovering and reusing adsorbents. Biomass-derived activated carbon adsorbents offer large adjustable specific surface area, hierarchically porous structure, strong adsorption capacity, and excellent high economic applicability. This paper focuses on reviewing the preparation methods of biomass-derived activated carbon in the past five years. The application of representative biomass-derived activated carbon in the adsorption of heavy metals preferentially was described to optimize the critical parameters of the activation type of samples and process conditions. The key factors of the adsorbent, the physicochemical properties of the heavy metals, and the adsorption conditions affecting the adsorption of heavy metals are highlighted. In addition, the challenges faced by biomass-derived activated carbon are also discussed.

Mesoporous multi-shelled hollow resin nanospheres with ultralow thermal conductivity

Hollow nanostructures exhibit enclosed or semi-enclosed spaces inside and the consequent features of restricting molecular motion, which is crucial for intrinsic physicochemical properties. Herein, we developed a new configuration of hollow nanostructures with more than three layers of shells and simultaneously integrated mesopores on every shell. The novel interior configuration expresses the characteristics of periodic interfaces and abundant mesopores. Benefiting from the suppression of gas molecule convection by boundary scattering, the thermal conductivity of mesoporous multi-shelled hollow resin nanospheres reaches 0.013 W m-1 K-1 at 298 K. The designed interior mesostructural configuration of hollow nanostructures provides an ideal platform to clarify the influence of nanostructure design on intrinsic physicochemical properties and propels the development of hollow nanostructures.

Ionic Liquid Modified Porous Polymer as a Dispersive Filter Extraction Adsorbent for Simple, Sensitive, and Efficient Determination of Chlorotriazine Herbicides in Irrigation Water

Triazine herbicides (TRZHs) are widely used in agricultural production, but their improper use can threaten the environment and organisms. Herein, rapid extraction of four chlorotriazine herbicides (Cl-TRZHs) in irrigation water was achieved using an ionic liquid modified porous m-aminophenol formaldehyde resin (IL-MAPFR) as a dispersive filter extraction (DFE) adsorbent. The IL-MAPFR shows excellent adsorption performance for four Cl-TRZHs (simazine, cyanazine, atrazine, and terbuthylazine), with a large specific surface area (158.1 m² g^-1) and fast mass transfer (2 min). The adsorption process conforms to the pseudo-second-order kinetics and Freundlich isotherm models. The four Cl-TRZHs were concentrated 12-16-fold after the IL-MAPFR-DFE method. Coupled with high-performance liquid chromatography, an accurate and sensitive determination method for four Cl-TRZHs in irrigation water was established, with low detection limit (0.11-0.20 ng mL^-1), high recoveries (91.5-110%), and excellent precision (relative standard deviations (RSDs) ≤ 8.4%). This method provides technical support for agricultural irrigation water quality monitoring and has great application potential in water safety, especially pesticide residues.

Mercapto-functionalized ordered mesoporous silica-modified PVDF membrane for efficiently scavenging Cd2+ from water

In this study, (3-mercaptopropyl) triethoxysilane (MPTMS)-modified ordered mesoporous silica (OMS) materials were prepared using a post-grifting method, with MPTMS as the organic functionalized reagent. The OMS materials were analyzed by FT-IR spectra, N₂ sorption, and small angle X-ray scattering to evaluate their potential for scavenging Cd²⁺ from water. Moreover, a (3-mercaptopropyl) triethoxysilane-functionalized ordered mesoporous silica modified polyvinylidene fluoride (MPTMS-OMS/PVDF) membrane was synthesized using the solvent phase inversion method to remediate wastewater containing heavy metal ions. The MPTMS-OMS was characterized by a maximum specific surface area of 422 m²/g, high surface hydrophilicity, and high pure water flux. The MPTMS-OMS/PVDF exhibited a dynamic adsorption capacity for Cd²⁺ in water. At an MPTMS-OMS content of 5 wt%, the Cd²⁺ removal efficiency was 90%, whereas the pure PVDF showed no Cd²⁺ adsorption capacity. These results highlight the potential of the MPTMS-OMS/PVDF membrane to eliminate Cd²⁺ during the decontamination of aqueous streams containing low-concentrations of contaminants.

An Overview of Metal-free Sustainable Nitrogen-based Catalytic Knoevenagel Condensation Reaction ‎

Knoevenagel condensation reaction counts as a vital condensation in organic chemistry due to the synthesis of valuable intermediates, ‎heterocycles, and fine chemicals from commercially available reactants through forming new C=C...

Formation of resorcinol-formaldehyde hollow nanoshells through a dissolution-regrowth process

We report here that dissolution and regrowth of resorcinol formaldehyde (RF) colloidal particles can occur spontaneously when they are subjected to etching in solvents such as ethanol and tetrahydrofuran, resulting in the formation of hollow nanostructures with controllable shell thickness. The hollowing process of the RF particles is attributed to their structural inhomogeneity, which results from the successive deposition of oligomers with different chain lengths during their initial growth. As the near-surface layer of RF colloids mainly consists of long-chain oligomers while the inner part consists of short-chain oligomers, selective etching removes the latter and produces the hollow structures. By revealing the important effects of the condensation degree of RF, the etching time and temperature, and the composition of solvents, we demonstrate that the morphology and structure of the resulting RF nanostructures can be conveniently and precisely controlled. This study not only improves our understanding of the structural heterogeneity of colloidal polymer particles, but also provides a practical and universal self-templated approach for the synthesis of hollow nanostructures.

Primary Amine-Functionalized Mesoporous Phenolic Resin-Supported Palladium Nanoparticles as an Effective and Stable Catalyst for Water-Medium Suzuki-Miyaura Coupling Reactions

Metal nanoparticles have been recognized and widely explored as unique catalysts for carbon-carbon coupling reactions. However, due to their extreme tendency to agglomeration, the generation and stabilization of metal nanoparticles in a porous matrix is an important research field. Herein, novel mesoporous phenolic resin-supported palladium nanoparticles (Pd@NH₂-MPRNs) were prepared via direct anionic exchange followed by gentle reduction by using primary amine-functionalized ordered mesoporous phenolic resin as the support. The obtained Pd@NH₂-MPRN material still possessed large surface area and ordered two-dimensional hexagonal mesoporous structure. Meanwhile, uniform and well-dispersed palladium nanoparticles were formed in the mesoporous channels, which could be attributed to an efficient complexation and stabilization effect derived from the primary amine groups. As a result, it can promote Suzuki coupling of less activated aromatic bromides to various biaryls in water with high conversion and selectivity. This excellent performance was attributed to small particle sizes, ordered mesopores, and a hydrophobic pore surface, which resulted in the decreased diffusion limitation and the increased active site accessibility. It is noted that it is competitive with the best palladium catalysts known for water-medium Suzuki coupling reaction, and it can be reused at least seven times without significant reduction in the catalytic efficiency, showing a good recyclability. Therefore, this work provides a new potential platform for designing and fabricating robust ordered mesoporous-polymer-supported metal nanoparticles for various catalytic applications.