Green synthesis of ZIF-8 tubular membranes from a recyclable 2-methylimidazole water-solvent solution by ZnO nanorods self-converted strategy for gas separation

Non-selective Defect Minimization towards Highly Efficient Metal-Organic Framework Membranes for Gas Separation

The persistence of defects in polycrystalline membranes poses a substantial obstacle to reaching the theoretical molecular sieving separation and scaling up production. The low membrane selectivity in most reported literature is largely due to the unavoidable non-selective defects during synthesis, leading to a mismatch between the well-defined pore structure of polycrystalline molecular sieve materials. This paper presents a novel approach for minimizing non-selective defects in metal-organic framework (MOF) membranes by a constricted crystal growth strategy in a confined environment. The in situ ZIF formation using the densely packed seeding array between the substrate and the pre-grown top ZIF layer yields a confined membrane interlayer, which is highly uniform with a tightly packed crystalline structure. Unlike uncontrolled crystal growth, we purposely regulate the interlayer membrane growth in the direction parallel to the substrate. A notable 99 % decrease in defects in the confined interlayer was achieved compared to the random-grown top layer, leading to a ~353 % increment in H2/N2 selectivity over the non-confined reference MOF membrane. The performance of this new membrane sits in the optimal range above the Robeson upper bound. The membrane boasts a balanced high H2 permeability (>5000 Barrer) and selectivity (>50), significantly surpassing peer ZIF membranes.

One-pot green synthesis of ZIF-8/IgG composite for the precise orientation and protection of antibody and its application in purification and detection of aflatoxins in peanut oil

This study presents a novel approach toward the one-pot green synthesis of ZIF-8/IgG composite, focusing on its precise orientation and protection of the anti-aflatoxins antibody. The antibody orientation is achieved through the specific binding of IgG to the Fc region of the antibody, while the antibody protection is accomplished by the structural change restriction of ZIF-8 framework to the antibody. Consequently, the antibody exhibits enhanced target capability and significantly improved tolerance to organic solvents. The ZIF-8/IgG/anti-AFT was employed for the purification and detection of AFTs by coupling with UPLC. Under optimized conditions, the recoveries of spiked AFTs in peanut oils are between 86.1% and 106.4%, with relative standard deviations (RSDs) ranging from 0.8% to 8.8%. The linearity range is 0.5-20.0 ng for AFB1 and AFG1, 0.125-5.0 ng for AFB2 and AFG2, the limit of detection is 0.1 ng for AFB1 and AFG1, 0.03 ng for AFB2 and AFG2.

Wrinkled metal-organic framework thin films with tunable Turing patterns for pliable integration

Flexible integration spurs diverse applications in metal-organic frameworks (MOFs). However, current configurations suffer from the trade-off between MOF loadings and mechanical compliance. We report a wrinkled configuration of MOF thin films. We established an interfacial synthesis confined and controlled by a polymer topcoat and achieved multiple Turing motifs in the wrinkled thin films. These films have complete MOF surface coverage and exhibit strain tolerance up to 53.2%. The enhanced mechanical properties allow film transfer onto various substrates. We obtained membranes with large H2/CO2 selectivity (41.2) and high H2 permeance (8.46 × 103 gas permeation units), showcasing negligible defects after transfer. We also achieved soft humidity sensors on delicate electrodes by avoiding exposure to harsh MOF synthesis conditions. These results highlight the potential of wrinkled MOF thin films for plug-and-play integration.

In situ electrochemical potential-induced synthesis of metal organic framework membrane on polymer support for H2/CO2 separation

Metal-Organic Framework (MOF) membranes act as selective layers have offered unprecedented opportunities for energy-efficient and cost-effective gas separation. Searching for the green and sustainable synthesis method of dense MOF membrane has received huge attention in both academia and industry. In this work, we demonstrate an in situ electrochemical potential-induced synthesis strategy to aqueously fabricate Metal Azolate Framework-4 (MAF-4) membranes on polypropylene (PP) support. The constant potential can induce the heterogeneous nucleation and growth of MAF-4, resulting an ultrathin membrane with the thickness of only 390 nm. This high-quality membrane exhibits a high H2/CO2 separation performance with the H2 permeance as high as 1565.75 GPU and selectivity of 11.6. The deployment of this environment friendly one-step fabrication method under mild reaction conditions, such as low-cost polymer substrate, water instead of organic solvent, room temperature and ambient pressure shows great promise for the scale-up of MOF membranes.

Green Synthesis of Zeolitic Imidazolate Frameworks: A Review of Their Characterization and Industrial and Medical Applications

Metal organic frameworks (MOF) are a class of hybrid networks of supramolecular solid materials comprising a large number of inorganic and organic linkers, all bound to metal ions in a well-organized fashion. Zeolitic imidazolate frameworks (ZIFs) are a sub-group of MOFs with imidazole as an organic linker to metals; it is rich in carbon, nitrogen, and transition metals. ZIFs combine the classical zeolite characteristics of thermal and chemical stability with pore-size tunability and the rich topological diversity of MOFs. Due to the energy crisis and the existence of organic solvents that lead to environmental hazards, considerable research efforts have been devoted to devising clean and sustainable synthesis routes for ZIFs to reduce the environmental impact of their preparation. Green chemistry is the key to sustainable development, as it will lead to new solutions to existing problems. Moreover, it will present opportunities for new processes and products and, at its heart, is scientific and technological innovation. The green chemistry approach seeks to redesign the materials that make up the basis of our society and our economy, including the materials that generate, store, and transport our energy, in ways that are benign for humans and the environment and that possess intrinsic sustainability. This study covers the principles of green chemistry as used in designing strategies for synthesizing greener, less toxic ZIFs the consume less energy to produce. First, the necessity of green methods in today's society, their replacement of the usual non-green methods and their benefits are discussed; then, various methods for the green synthesis of ZIF compounds, such as hydrothermally, ionothermally, and by the electrospray technique, are considered. These methods use the least harmful and toxic substances, especially concerning organic solvents, and are also more economical. When a compound is synthesized by a green method, a question arises as to whether these compounds can replace the same compounds as synthesized by non-green methods. For example, is the thermal stability of these compounds (which is one of the most important features of ZIFs) preserved? Therefore, after studying the methods of identifying these compounds, in the last part, there is an in-depth discussion on the various applications of these green-synthesized compounds.

Seed assisted synthesis of anionic metal organic framework membrane for selective and permeable hydrogen separation

Hydrogen selective metal organic framework (MOF) membranes with excellent performances are still in high demand. Here, we are developing an anionic MOF material of CPM-5 into a membrane for H2...

Life Cycle Assessment on Different Synthetic Routes of ZIF-8 Nanomaterials

In the last twenty years, research activity around the environmental applications of metal–organic frameworks has bloomed due to their CO2 capture ability, tunable properties, porosity, and well-defined crystalline structure. Thus, hundreds of MOFs have been developed. However, the impact of their production on the environment has not been investigated as thoroughly as their potential applications. In this work, the environmental performance of various synthetic routes of MOF nanoparticles, in particular ZIF-8, is assessed through a life cycle assessment. For this purpose, five representative synthesis routes were considered, and synthesis data were obtained based on available literature. The synthesis included different solvents (de-ionized water, methanol, dimethylformamide) as well as different synthetic steps (i.e., hours of drying, stirring, precursor). The findings revealed that the main environmental weak points identified during production were: (a) the use of dimethylformamide (DMF) and methanol (MeOH) as substances impacting environmental sustainability, which accounted for more than 85% of the overall environmental impacts in those synthetic routes where they were utilized as solvents and as cleaning agents at the same time; (b) the electricity consumption, especially due to the Greek energy mix which is fossil-fuel dependent, and accounted for up to 13% of the overall environmental impacts in some synthetic routes. Nonetheless, for the optimization of the impacts provided by the energy use, suggestions are made based on the use of alternative, cleaner renewable energy sources, which (for the case of wind energy) will decrease the impacts by up to 2%.

Mechanism and Compatibility of Pretreated Lignocellulosic Biomass and Polymeric Mixed Matrix Membranes: A Review

In this paper, a review of the compatibility of polymeric membranes with lignocellulosic biomass is presented. The structure and composition of lignocellulosic biomass which could enhance membrane fabrications are considered. However, strong cell walls and interchain hindrances have limited the commercial-scale applications of raw lignocellulosic biomasses. These shortcomings can be surpassed to improve lignocellulosic biomass applications by using the proposed pretreatment methods, including physical and chemical methods, before incorporation into a single-polymer or copolymer matrix. It is imperative to understand the characteristics of lignocellulosic biomass and polymeric membranes, as well as to investigate membrane materials and how the separation performance of polymeric membranes containing lignocellulosic biomass can be influenced. Hence, lignocellulosic biomass and polymer modification and interfacial morphology improvement become necessary in producing mixed matrix membranes (MMMs). In general, the present study has shown that future membrane generations could attain high performance, e.g., CO2 separation using MMMs containing pretreated lignocellulosic biomasses with reachable hydroxyl group radicals.