Effect of pyrolysis temperature on characteristics and chloramphenicol adsorption performance of NH2-MIL-53(Al)-derived amine-functionalized porous carbons

Several activities such as aquaculture, human and feedstock therapies can directly release antibiotics into water. Due to high stability, low hydrolysis and non-biodegradation, they can accumulate in the aqueous environment and transport to aquatic species. Here, we synthesized amine-functionalized porous carbons (ANC) by a direct-pyrolysis process of NH2-MIL-53(Al) as a sacrificial template at between 600 and 900 °C and utilized them to eliminate chloramphenicol antibiotic from water. The NH2-MIL-53(Al)-derived porous carbons obtained high surface areas (304.7-1600 m2 g-1) and chloramphenicol adsorption capacities (148.3-261.5 mg g-1). Several factors such as hydrogen bonding, Yoshida hydrogen bonding, and π-π interaction, hydrophobic interaction possibly controlled adsorption mechanisms. The ANC800 could be reused four cycles along with high stability in structure. As a result, NH2-MIL-53(Al)-derived porous carbons are recommended as recyclable and efficient adsorbents to the treatment of antibiotics in water.

Trimetallic carbon-based catalysts derived from metal-organic frameworks for electro-Fenton removal of aqueous pesticides

Pesticide overuse has posed a threat to agricultural community as well as aquatic animals. Heterogeneous electro-Fenton (HEF) processes have received considerable attention for aqueous contaminants removal, and metal-organic frameworks (MOFs) serve as promising templates for fabrication of carbon-based HEF catalysts with low Fe leaching and enhanced stability. Herein, multimetallic MOF-derived HEF catalysts CMOFs@PCM have been demonstrated as efficient and stable HEF catalysts for aqueous pesticide degradation and mineralization. The porous carbon monolith (PCM) substrate effectively catalyzed 2-electron oxygen reduction reaction (ORR) over the pH range of 4-10 to in situ generate H₂O₂, which was then activated by the anchored Fe₃O₄, Fe₃C and NiO into OH for pesticide degradation. Fe₈Al₇Ni₅-CMOF@PCM achieved over 90% napropamide degradation within 60 min in the pH range of 4-10, and 96% degradation at neutral condition, 39% higher than monometallic CMIL-88(Fe)@PCM. Meanwhile, the embedded NiO and γ-Al₂O₃ showed synergistic effect in promoting the catalytic activity of Fe sites, resulting in substantially enhanced performance of trimetallic Fe_xAl_yNi_z-CMOF@PCM compared to the monometallic counterparts. On the other hand, the unique core-shell structure and Fe₃C interlayer formed by co-pyrolyzing Fe-containing MOFs-NH₂ with PCM greatly minimized the metal leaching and enhanced the stability of the electrocatalysts.

A mild and efficient method for the synthesis of pyrroles using MIL-53(Al) as a catalyst under solvent-free sonication

A highly efficient method for the synthesis of pyrroles using MIL-53(Al) as a catalyst has been developed under solvent-free sonication. This reaction has a broad substrate scope and high yields were obtained within a short reaction time. Remarkably, no additional additives and volatile organic solvent are required for this method and the MIL-53(Al) could be recovered and reused several times without significant drop-off in catalytic activity.

FeCl3-catalyzed dimerization/elimination of 1,1-diarylalkenes: efficient synthesis of functionalized 4H-chromenes

An efficient synthesis of valuable poly-substituted 4H-chromenes was developed via a [4 + 2] cycloaddition followed by the elimination of 1,1-diarylalkenes. The inexpensive FeCl₃ salt has proven to be an efficient catalyst for this transformation. The commercial availability of the catalyst and reagents, together with a convenient procedure, makes this an attractive method for 4H-chromene synthesis.

New functionalized MIL-53(In) solids: syntheses, characterization, sorption, and structural flexibility

The syntheses and characterization of a series of functionalized MIL-53(In) solids have been reported. Chemical groups with variations in steric hindrance and chemical nature (–(OH)₂, –Br or –NO₂ groups) were introduced through the terephthalate linker to modify the pore surface. Single crystal X-ray diffraction data, N₂ adsorption–desorption isotherms, and infrared spectra were systematically investigated to explore the impact of the functional groups grafted onto the organic linker on the dynamic behaviour of these highly flexible hybrid porous frameworks. Owing to the distinctive steric hindrance and chemical nature, the different substituents can influence the interactions between the framework and the trapped molecules, further influencing the flexibility of the materials. Dihydroxyl modified MIL-53(In) exhibits no nitrogen accessible porosity. Notably, functionalization by –Br and –NO₂ groups leads to the different capabilities of the corresponding solids to accommodate N₂ molecules.

Syntheses, characterization, sorption, and structural flexibility of new functionalized MIL-53(In) solids were fully investigated.

A Zn based metal organic framework nanocomposite: synthesis, characterization and application for preconcentration of cadmium prior to its determination by FAAS

The SEM image of a synthesized metal–organic framework (MOF) with Zn and benzene-1,3-dicarboxylic acid via hydrothermal method as a selective nanoadsorbent for the preconcentration of trace amount of cadmium via SPE method and determination by FAAS.