Co/Ni/Cu-NH2BDC MOF@natural Egyptian zeolite ore nanocomposite for calcium ion removal in water softening applications

Water softening is a treatment process required to remove calcium (Ca(II)) and magnesium (Mg(II)) cations from water streams. Nanocomposites can provide solutions for such multiple challenges and have high performance and low application costs. In this work, a multimetallic cobalt, nickel, and copper 2-aminoterephthalic acid metal-organic framework ((Co/Ni/Cu-NH2BDC) MOF) was synthesized by a simple solvothermal technique. This MOF was supported on an Egyptian natural zeolite ore and was used for the adsorption of Ca(II) ions for water-softening applications. The adsorbent was characterized using Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), N2 adsorption-desorption isotherms, and zeta potential measurements. The adsorption isotherm data for the prepared adsorbent toward Ca(II) were best fit using the Redlich-Peterson model and showed a maximum adsorption capacity of 88.1 mg/g. The adsorption kinetics revealed an equilibrium time of 10 min, which was best fit using the Avrami model. The intermolecular interactions of Ca(II) ions with zeolite and MOF were investigated by Monte Carlo simulations, molecular dynamics simulations, and FTIR and XRD analyses. The adsorption sites in the zeolite structure were oxygen atoms, while those in the MOF structure were amine nitrogen atoms. The Ca(II) ions are coordinated with the solvent molecules in both structures. Finally, the in vitro cytotoxicity of this nanocomposite was assessed, revealing viability levels of 74.57 ± 2.1% and 21 ± 2.79% for Vero and African green monkey kidney and human liver (HepG2) cells, respectively. Cytotoxicity assays help assess the environmental impact of these materials, ensuring that they do not harm aquatic organisms or disrupt ecosystems. Thus, this study demonstrated the valorization of MOF/zeolite as a valuable and industry-ready adsorbent that can appropriate Ca(II) contaminants from aqueous streams.

Impact of Compression on the Textural and Structural Properties of CPO-27(Ni)

The employment of metal-organic frameworks in powder form is undesirable from an industrial perspective due to process and safety issues. This work is devoted to evaluating the impact of compression on the textural and structural properties of CPO-27(Ni). For this purpose, CPO-27(Ni) was synthesized under hydrosolvothermal conditions and characterized. Then, the resulting powder was compressed into binderless pellets using variable compression forces ranging from 5-90 kN (37-678 MPa) and characterized by means of nitrogen adsorption/desorption, thermogravimetric analysis and powder X-ray diffraction to evaluate textural, thermal and structural changes. Both textural and structural properties decreased with increasing compression force. Thermal stability was impacted in pellets compressed at forces over 70 kN. CPO-27(Ni) pelletized at 5, 8 and 10 kN, and retained more than 94% of its initial textural properties, while a loss of about one-third of the textural property was observed for the two most compressed samples (70 and 90 kN) compared to the starting powder.

Pd/MIL-100(Fe) as hydrogen activator for FeIII/FeII cycle: Fenton removal of sulfamethazine

Masses of iron sludge generated from engineering practice of classic Fenton reaction constraints its further promotion. Accelerating the FeIII/FeII cycle may be conducive to reducing the initial ferrous slat dosage and the final iron sludge. Based on the reduction of Pd/MIL-100(Fe)-activated hydrogen, an improved Fenton system named MHACF-MIL-100(Fe) was developed at ambient temperature and pressure. 97.8% of sulfamethazine, the target pollutant in this work, could be degraded in 5 min under the conditions of 20 mM H2O2, 25 μM ferrous chloride, initial pH 3.0, 2 g·L-1 composite catalyst Pd/MIL-100(Fe) and hydrogen gas 60 mL·min-1. Combining density functional theory (DFT) calculation and intermediate detection, the degradation of this antibiotic was inferred to start from the cleavage of N-S bond. The catalytic of Pd/MIL-100(Fe), demonstrated by the removal efficiency of SMT and the catalyst morphology, remained intact after six reaction cycles. The present study provides an insight into the promotion of Fenton reaction.

Binding Materials for MOF Monolith Shaping Processes: A Review towards Real Life Application

Metal–organic frameworks (MOFs) could be utilized for a wide range of applications such as sorption, catalysis, chromatography, energy storage, sensors, drug delivery, and nonlinear optics. However, to date, there are very few examples of MOFs exploited on a commercial scale. Nevertheless, progress in MOF-related research is currently paving the way to new industrial opportunities, fostering applications and processes interconnecting fundamental chemistry with engineering and relevant sectors. Yet, the fabrication of porous MOF materials within resistant structures is a key challenge impeding their wide commercial use for processes such as adsorptive separation. In fact, the integration of nano-scale MOF crystallic structures into bulk components that can maintain the desired characteristics, i.e., size, shape, and mechanical stability, is a prerequisite for their wide practical use in many applications. At the same time, it requires sophisticated shaping techniques that can structure nano/micro-crystalline fine powders of MOFs into diverse types of macroscopic bodies such as monoliths. Under this framework, this review aims to bridge the gap between research advances and industrial necessities for fostering MOF applications into real life. Therefore, it critically explores recent advances in the shaping and production of MOF macro structures with regard to the binding materials that have received little attention to date, but have the potential to give new perspectives in the industrial applicability of MOFs. Moreover, it proposes future paths that can be adopted from both academy and industry and can further boost MOF exploitation.

Rational Process Design for Facile Fabrication of Dual Functional Hybrid Membrane of MOF and Electrospun Nanofiber towards High Removal Efficiency of PM2.5 and Toxic Gases

The application of nanofiber (NF) and porous metal-organic framework (MOF) has increasingly attracted attention for the proptection of public health. This composite platform provides the physical sieving of particulate matter (PMs) and capturing gases, serving as an outstanding filtering medium with lightweight and multifunctionality. Herein, process design and optimization were performed to produce a multifunctional membrane comprised NFs and MOF particles. Electrospinning/electrospray techniques were used to fabricate a hybrid membrane of poly(vinyl alcohol) NF and Fe-BTC as an adsorptive MOF on a macroporous nonwoven (NW). Three types of filters were prepared by varying the order of processing steps, i.e., MOF/NF/NW, MOF+NF/NW, and NF/MOF/NW, to elucidate the effect of the fabrication process in the filtration of air pollutant. The optimal filtration performance was achieved in MOF+NF/NW system: the highest filtration efficiency (97%) and outstanding gas capturing efficiencies (≈60% and ≈35% decreases from initial NH₃ and H₂ S concentrations, respectively). However, when air permeability and filtration efficiency are considered, the most desirable configuration for personal protection equipment (PPE) was NF/MOF/NW system, which effectively enabled comfortable breathing without compromising the lightweight and multifunctional performance. This article is protected by copyright. All rights reserved.

Surviving Under Pressure: The Role of Solvent, Crystal Size, and Morphology During Pelletization of Metal-Organic Frameworks

As metal-organic frameworks (MOFs) gain traction for applications, such as hydrogen storage, it is essential to form the as-synthesized powder materials into shaped bodies with high packing densities to maximize their volumetric performance. Mechanical compaction, which involves compressing the materials at high pressure, has been reported to yield high monolith density but often results in a significant loss in accessible porosity. Herein, we sought to systematically control (1) crystal size, (2) solvation, and (3) compacting pressure in the pelletization process to achieve high packing density without compromising the porosity that makes MOFs functional. It was determined that solvation is the most critical factor among the three factors examined. Solvation that exceeds the pore volume prevents the framework from collapsing, allowing for porosity to be maintained through pelletization. Higher pelletization pressure results in higher packing density, with extensive loss of porosity being observed at a higher pressure if the solvation is below the pore volume. Lastly, we observed that the morphology and size of the MOF particles result in variation in the highest achievable packing efficiency, but these numbers (75%) are still greater than many existing techniques used to form MOFs. We concluded that the application of pressure through pelletization is a suitable and widely applicable technique for forming high-density MOF-monoliths.

Controllable Synthesis of 1, 3, 5-tris (1H-benzo[d]imidazole-2-yl) Benzene-Based MOFs

The growing interest in metal–organic frameworks (MOFs) in both industrial and scientific circles has increased in the last twenty years, owing to their crystallinity, structural versatility, and controlled porosity. In this study, we present three novel MOFs obtained from the 1, 3, 5-tris (1H-benzo[d]imidazole-2-yl) benzene (TIBM) organic linker. The formed TIBM crystal powders were characterized by scanning electron microscopy (SEM) to estimate the morphology of the particles, powder X-ray diffraction (XRD) to confirm the crystal structure, Brunauer–Emmett–Teller (BET) method for structural analysis, and thermogravimetric measurements to examine the thermal stability. The TIBM-Cu MOF showed excellent CO2 (3.60 mmol/g) adsorption capacity at 1 bar and 298 K, because of the open Cu site, compared to TIBM-Cr (1.6 mmol/g) and TIBM-Al (2.1 mmol/g). Additionally, due to the high porosity (0.3–1.5 nm), TIBM-Cu MOF showed a considerable CO2/N2 selectivity (53) compared to TIBM-Al (35) and TIBM-Cr (10).

Ionic liquid facilitated melting of the metal-organic framework ZIF-8

Hybrid glasses from melt-quenched metal-organic frameworks (MOFs) have been emerging as a new class of materials, which combine the functional properties of crystalline MOFs with the processability of glasses. However, only a handful of the crystalline MOFs are meltable. Porosity and metal-linker interaction strength have both been identified as crucial parameters in the trade-off between thermal decomposition of the organic linker and, more desirably, melting. For example, the inability of the prototypical zeolitic imidazolate framework (ZIF) ZIF-8 to melt, is ascribed to the instability of the organic linker upon dissociation from the metal center. Here, we demonstrate that the incorporation of an ionic liquid (IL) into the porous interior of ZIF-8 provides a means to reduce its melting temperature to below its thermal decomposition temperature. Our structural studies show that the prevention of decomposition, and successful melting, is due to the IL interactions stabilizing the rapidly dissociating ZIF-8 linkers upon heating. This understanding may act as a general guide for extending the range of meltable MOF materials and, hence, the chemical and structural variety of MOF-derived glasses.

Mechanical rigidity of a shape-memory metal-organic framework increases by crystal downsizing

Soft porous nanocrystals with a pronounced shape-memory effect exhibit two- to three-fold increase in elastic modulus compared to the microcrystalline counterpart as determined by atomic force microscopy nanoindentation. The increase in rigidity is consistent with the known shape-memory effect displayed by the framework solid at the nanoscale. Crystal downsizing can offer new avenues for tailoring the mechanical properties of metal-organic frameworks.

Adsorber heat exchanger using Al-fumarate beads for heat-pump applications - a transport study

Metal-Organic Frameworks (MOFs), thanks to their type V water adsorption isotherms ("S-Shape") and large water capacities, are considered as potential breakthrough adsorbents for heat-pump applications. In particular, Al(OH)-fumarate could enable efficient regeneration at a lower temperature than silica-gel which would allow us to address the conversion of waste heat at low temperature such as found in data centers. Despite its greater adsorption capacity features, heat and mass transport limitations could jeopardize the potential performance of Al(OH)-fumarate. Heat and mass transport depend on the size of the bodies (mm range), their packing and on the pore structures, i.e. macro-mesopore volumes and sizes. This paper describes the cost-efficient and scalable synthesis and shaping processes of Al(OH)-fumarate beads of various sizes appropriate for use in water Adsorption Heat-Pumps (AHPs). The objective was to study transport limitations (i.e. mass and heat) in practical e beads which meet mechanical stability requirements. Dynamic data at the grain scale was obtained by the Large Temperature Jump method while dynamic data at the adsorber scale was obtained on a heat exchanger filled with more than 1 kg of Al(OH)-fumarate beads. Whereas the binder content had little impact on mass and heat transfer in this study, we found that Knudsen diffusion in mesopores of the grain may be the main limiting factor at the grain scale. At the adsorber scale, heat-transfer within the bed packing as well as to the heat exchanger is likely responsible for the slow adsorption and desorption kinetics which have been observed for very low desorption temperature. Finally, the dynamic aspects of the observed water adsorption isotherm shift with temperature are discussed in light of reported reversible structure modification upon temperature triggered water adsorption-desorption.

Mechanical properties of metal-organic frameworks

As the field of metal–organic frameworks (MOFs) continues to grow, the physical stability and mechanical properties of these porous materials has become a topic of great interest.

As the field of metal–organic frameworks (MOFs) continues to grow, the physical stability and mechanical properties of these porous materials has become a topic of great interest. While strategies for synthesizing MOFs with desirable chemical functionalities or pore sizes have been established over the past twenty years, design principles to modulate the response of MOFs to mechanical stress are still underdeveloped. The inherent porosity of these frameworks results in many interesting and sometimes unexpected phenomena upon exposure to elevated pressures and other physical stimuli. Beyond its fundamental importance, an understanding of mechanical properties (e.g. bulk modulus, shear modulus, Young's modulus, linear compressibility, and Poisson's ratio) plays an essential role in the post-synthetic processing of MOFs, which has implications in the successful transition of these materials from academic interest to industrial relevance. This perspective provides a concise overview of the efforts to understand the mechanical properties of MOFs through experimental and computational methods. Additionally, current limitations and possible future directions for the field are also discussed briefly.

Synthesis and Properties of a Compositional Series of MIL-53(Al) Metal-Organic Framework Crystal-Glass Composites

Metal–organic framework crystal-glass composites (MOF-CGCs) are materials in which a crystalline MOF is dispersed within a MOF glass. In this work, we explore the room-temperature stabilization of the open-pore form of MIL-53(Al), usually observed at high temperature, which occurs upon encapsulation within a ZIF-62(Zn) MOF glass matrix. A series of MOF-CGCs containing different loadings of MIL-53(Al) were synthesized and characterized using X-ray diffraction and nuclear magnetic resonance spectroscopy. An upper limit of MIL-53(Al) that can be stabilized in the composite was determined for the first time. The nanostructure of the composites was probed using pair distribution function analysis and scanning transmission electron microscopy. Notably, the distribution and integrity of the crystalline component in a sample series were determined, and these findings were related to the MOF-CGC gas adsorption capacity in order to identify the optimal loading necessary for maximum CO₂ sorption capacity.

Novel metal–organic framework materials: blends, liquids, glasses and crystal–glass composites

This Feature Article reviews a range of amorphisation mechanisms of Metal–Organic Frameworks (MOFs) and presents recent advances to produce novel MOF materials including porous MOF glasses, MOF crystal–glass composites, flux melted MOF glasses and blended zeolitic imidazolate framework glasses.

Simultaneous laser-induced synthesis and micro-patterning of a metal organic framework

Micro-patterning of a metal organic framework (MOF) from a solution of precursors is achieved by local laser heating, alleviating the need for pre-preparation and stabilization.

Simultaneous neutron powder diffraction and microwave dielectric studies of ammonia absorption in metal-organic framework systems

Ammonia absorption has been investigated in metal-organic frameworks (UiO-67, HKUST-1 and CPO-27-Co) using custom-built apparatus that allows simultaneous neutron powder diffraction (NPD), microwave dielectric characterisation and out-gas mass spectroscopy of solid-state materials during ammonia adsorption. Deuterated ammonia was flowed through the sample and absorption monitored using mass flow meters and mass spectroscopy. Argon gas was then flowed through the ammoniated sample to cause ammonia desorption. Changes in structure found from NPD measurements were compared to changes in dielectric characteristics to differentiate physisorbed and metal-coordinated ammonia, as well as determine decomposition of sample materials. The results of these studies allow the identification of materials with useful ammonia storage properties and provides a new metric for the measurement of gas absorption within mesoporous solids.