A defects-free ZIF-90/6FDA-Durene membrane based on the hydrogen bonding/covalent bonding interaction for gas separation

Amino-Modified ZIF-90 for Effective Adsorption of Au(III) in Environmental Water

In this work, amino-modified ZIF-90 (NH2-ZIF-90) was prepared by using butylamine as a modifier, and its effectiveness in adsorbing Au(III) from environmental samples was investigated. The morphology and structure of NH2-ZIF-90 were analyzed via SEM, XRD, FT-IR, and XPS. Optimal adsorption occurred after 12 h of shaking in a pH = 5 aqueous solution with 2 mg mL-1 NH2-ZIF-90. The adsorption kinetics conformed to a pseudo-second-order model, and the equilibrium data fit the Freundlich isotherm model well. Finally, NH2-ZIF-90 was successfully used in lake water and tap water samples for Au(III) adsorption, with recovery rates ranging from 81.0% to 93.3%. This study presents a novel approach for addressing Au(III) adsorption challenges.

A High-Quality Mixed Matrix Membrane with Nanosheets Assembled and Uniformly Dispersed Fillers for Ethanol Recovery

A high-quality filler within mixed matrix membranes, coupled with uniform dispersity, endows a high-efficiency transfer pathway for the significant improvement on separation performance. In this work, a zeolite-typed MCM-22 filler is reported that is doped into polydimethylsiloxane (PDMS) matrix by ultrafast photo-curing technique. The unique structure of nanosheets assembly layer by layer endows the continuous transfer channels towards penetrate molecules because of the inter-connective nanosheets within PDMS matrix. Furthermore, an ultrafast freezing effect produced by fast photo-curing is used to overcome the key issue, namely filler aggregation, and further eliminates defects. When pervaporative separating a 5 wt% ethanol aqueous solution, the resulting MCM-22/PDMS membrane exhibits an excellent membrane flux of 1486 g m-2 h-1 with an ethanol separation factor of 10.2. Considering a biobased route for ethanol production, the gas stripping and vapor permeation through this membrane also shows a great enrichment performance, and the concentrated ethanol is up to 65.6 wt%. Overall, this MCM-22/PDMS membrane shows a high separation ability for ethanol benefited from a unique structure deign of fillers and ultrafast curing speed of PDMS, and has a great potential for bioethanol separation from cellulosic ethanol fermentation.

Hierarchically porous ZnO derived from zeolitic imidazolate frameworks for high-sensitive MEMS NO2 sensor

Three-dimensional (3D) porous metal oxide nanomaterials with controllable morphology and well-defined pore size have attracted extensive attention in the field of gas sensing. Herein, hierarchically porous ZnO-450 was obtained simply by annealing Zeolitic Imidazolate Frameworks (ZIF-90) microcrystals at an optimal temperature of 450 °C, and the effect of annealing temperature on the formation of porous nanostructure was discussed. Then the as-obtained ZnO-450 was employed as sensing materials to construct a Micro-Electro-Mechanical System (MEMS) gas sensor for detecting NO2. The MEMS sensor based on ZnO-450 displays the excellent gas-sensing performances at a lower working temperature (190 °C), such as high response value (242.18% @ 10 ppm), fast response/recovery time (9/26 s) and ultralow limit of detection (35 ppb). The ZnO-450 sensor shows better sensing performance for NO2 detection than ZnO-based composites materials or commercial ZnO nanoparticles (NPs), which are attributed to its unique hierarchically structures with high porosity and larger surface area. This ZIFs driven strategy can be expected to pave a new pathway for the design of high-performance NO2 sensors.

Recent advances in the interfacial engineering of MOF-based mixed matrix membranes for gas separation

The membrane process stands as a promising and transformative technology for efficient gas separation due to its high energy efficiency, operational simplicity, low environmental impact, and easy up-and-down scaling. Metal-organic framework (MOF)-polymer mixed matrix membranes (MMMs) combine MOFs' superior gas-separation performance with polymers' processing versatility, offering the opportunity to address the limitations of pure polymer or inorganic membranes for large-scale integration. However, the incompatibility between the rigid MOFs and flexible polymer chains poses a challenge in MOF MMM fabrication, which can cause issues such as MOF agglomeration, sedimentation, and interfacial defects, substantially weakening membrane separation efficiency and mechanical properties, particularly gas separation. This review focuses on engineering MMMs' interfaces, detailing recent strategies for reducing interfacial defects, improving MOF dispersion, and enhancing MOF loading. Advanced characterisation techniques for understanding membrane properties, specifically the MOF-polymer interface, are outlined. Lastly, it explores the remaining challenges in MMM research and outlines potential future research directions.

Covalent connections between metal-organic frameworks and polymers including covalent organic frameworks

Hybrid composite materials combining metal-organic frameworks (MOFs) and polymers have emerged as a versatile platform for a broad range of applications. The crystalline, porous nature of MOFs and the flexibility and processability of polymers are synergistically integrated in MOF-polymer composite materials. Covalent bonds, which form between two distinct materials, have been extensively studied as a means of creating strong molecular connections to facilitate the dispersion of "hard" MOF particles in "soft" polymers. Numerous organic transformations have been applied to post-synthetically connect MOFs with polymeric species, resulting in a variety of covalently connected MOF-polymer systems with unique properties that are dependent on the characteristics of the MOFs, polymers, and connection modes. In this review, we provide a comprehensive overview of the development and strategies involved in preparing covalently connected MOFs and polymers, including recently developed MOF-covalent organic framework composites. The covalent bonds, grafting strategies, types of MOFs, and polymer backbones are summarized and categorized, along with their respective applications. We highlight how this knowledge can serve as a basis for preparing macromolecular composites with advanced functionality.