Metal Organic Framework MIL-101 Research Articles

Metal-Organic Framework-Templated Synthesis of Nickel-Alumina Nanocatalysts Improves Catalyst-Support Interaction for Higher Activity and Stability in Biogas Reforming under Controlled Oxidizing Conditions.

Tri-reforming methane with CO2, O2, and H2O mixtures requires a delicate balance of dry-reforming, partial oxidation, and steam-reforming reactions to improve the CO2 conversion and H2/CO ratio. Nickel-alumina has been reported before for the tri-reforming of methane, although at higher temperatures (>900 °C). This is because the current approaches for nickel-alumina synthesis are ineffective in generating stronger catalyst-support interactions necessary to maintain higher active sites and stall carbon nanotube (CNT) deposition. Here, we report a synthesis method that allows controlled loading of nickel on alumina-based MIL-53 metal-organic framework followed by calcination to generate 2.5-10 wt % nickel nanoparticles dispersed on alumina. The 5 wt % nickel-alumina mixtures resulted in nanometer-sized crystallites, better metal dispersion, and more active sites for enhanced catalytic activity. This optimal loading of nickel allows stronger interaction with alumina for over 100 h of stable performance of tri-reforming at 800 °C, achieving ∼98% CH4 conversion, ∼36% CO2 conversion, and no carbon deposition while producing Fischer-Tropsch-ready feed containing a H2/CO ratio of 3.2.

Separator functionalization realizing stable zinc anode through microporous metal-organic framework with special functional group

Aqueous zinc ion batteries (AZIBs) have been regarded as one of the most promising energy storage systems because of their security, high specific capacity and abundant zinc resources, etc. Despite the promising prospects of AZIBs, their practical application is still plagued by dendrite and side reactions on zinc surface. In this paper, glass fiber separators were modified by in-situ loading metal-organic framework MIL-125 (M-125) and its -NH2-functionalized material (NM-125). The designed separator pore structure was successfully adjusted and endowed with -NH2 functional groups, which can ultimately dramatically enhance the electrochemical performance of AZIBs under practical operation conditions. The functionalized NM-125 with smaller pore size and particle size enables NM-125-GF to prevent the transport of macromolecular anions in the electrolyte, guiding and promoting zinc ions to undergo an orderly migration. In addition, -NH2 of NM-125 can adsorb Zn2+ and detach them from the solvated structure, inhibiting the generation of anode-side reactions and optimizing battery performance. Notably, Zn||MnO2 full cell assembled with -NH2 functionalized separator also shows a high initial discharge specific capacity (160.2 mAh g-1) with a high capacity retention of ∼99.8% even after 700 cycles. The rational design of the functionalized separator provides a useful guideline for optimizing high-performance AZIBs.

Efficient degradation of DDBAC in water by a heterogeneous Vis/H2O2 catalytic system based on MIL-53(Fe)

In this study, the iron-based metal–organic framework MIL-53(Fe) was successfully prepared by a solvent method and used as a photocatalyst for the efficient degradation of DDBAC under visible light. The morphology, structure and photocatalytic properties of MIL-53(Fe) were investigated by SEM, XRD, XPS and UV–vis DRS characterization methods. The optimum conditions for the degradation of DD pathways of DDBAC were analyzed in combination with DFT calculations. Based on molecular orbital theory and free radical quenching experiments, it was demonstrated that hydroxyl radicals were the main contributors in the oxidative degradation of DDBAC. The toxicity of DDBAC and its intermediates was evaluated by culturing Chlorella vulgaris, and the results showed that the Vis/MIL-53(Fe)/H2O2 system was capable of solution detoxification.

Eco-Friendly and Low-Cost Synthesis of Transparent Antiviral- and Antibacterial-Coated Films Based on Cu2O and MIL-53(Al).

This research presents the development of an innovative antimicrobial coating consisting of cuprous oxide (Cu2O) integrated with the metal-organic framework MIL-53(Al) through an eco-friendly and low-cost synthesis method that employs glucose as a reducing agent under mild conditions. The microstructural properties of the composite materials were characterized by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The antibacterial efficacy of the Cu2O-MIL-53(Al) (CuM) composite was assessed against Escherichia coli and Staphylococcus aureus, achieving a reduction efficacy of 99.99% with 5% copper incorporated into the MIL-53(Al) framework within a contact time of 24 h. The incorporation of CuM into a macromolecular host matrix of polyurethane-carboxymethylcellulose (CuM/PUD-CMC), applied as a coating on a low-cost plastic film, produced a transparent film with 87.10% transparency. This coating demonstrated a 99.99% reduction in E. coli and S. aureus populations within a contact time of 24 h. The CuM/PUD-CMC coating demonstrated substantial antiviral efficacy, achieving inactivation rates of 99.35% for Human Coronavirus 229E, 99.40% for Influenza A virus, and 97.76% for Enterovirus 71 within a contact time of 5 min. The CuM nanoparticles exhibited low toxicity toward zebrafish while effectively eradicating bacteria and inactivating viruses. The proposed low-cost material and coating method demonstrate significant potential as a broad-spectrum antimicrobial and antiviral agent, highlighting its suitability for various applications in biomedical and healthcare formulations.

Novel Rh catalytic systems based on microporous metal-organic framework MIL-53(Al) for “green” ethylene hydroformylation

Novel Rh catalytic systems based on microporous metal-organic framework MIL-53(Al) for “green” ethylene hydroformylation

Fabrication of ratiometric molecular imprinting electrochemiluminescence sensor based on polyethyleneimine hydrogel loading layered bimetallic hydroxide and MIL-125@Ru(bpy)32+ for sensitive tetracycline detection

In this work, layered Co-Ni bimetallic hydroxide was synthesized and combined with polyethyleneimine hydrogel (PEI@LDH) as substrate material, then the metal-organic framework MIL-125 loaded Ru(bpy)32+ (MIL@Ru) was added as single luminophore, followed by electrochemical deposition of tetracycline (TC) imprinted copolymer of hydroquinone and o-phenylenediamine to construct an electrochemiluminescent (ECL) sensor for TC detection. The stable and sensitive luminophore MIL@Ru associating with co-reactant K2S2O8 in the solution could cause a cathode ECL signal sensing TC, it could also associate with the immobilized co-reactant PEI hydrogel to produce a stable anode ECL signal acting as a reference. The LDH had catalysis and could efficiently amplify both anode and cathode ECL signals. Therefore, the constructed single luminophore based ratiometric ECL sensor displayed high selectivity, sensitivity and reproducibility. Under the selected testing conditions, the linear response range was 0.01 μmol L−1 to 1 mmol L−1 and the detection limit reached 8 nmol L−1. Its good practicability was validated by determining TC in different actual samples. Hence, the ratiometric MIP-ECL sensor was quite promising.

Competent CuS QDs@Fe MIL101 heterojunction for Sunlight-driven degradation of pharmaceutical contaminants from wastewater

In this study, we introduce an advanced photocatalyst developed by integrating copper sulfide quantum dots (CuS QDs) with an iron-based metal–organic framework (MOF), specifically Fe MIL101. The resulting CuS QDs@Fe MIL101 photocatalyst is engineered to efficiently degrade meloxicam (MLX) under simulated sunlight. The heterojunctions were generated by incorporating different concentrations of CuS QDs (5 %, 10 %, 15 %, 20 %, and 50 %) into the Fe MIL101 MOF matrix using the microwave-assisted hydrothermal method. The results of the XRD and the TEM studies confirmed the formation of the heterojunctions, which maintain the structural integrity of both CuS QDs and Fe MIL101. The BET measurements indicated a decrease in surface area upon CuS QDs incorporation, attributed to porés blockage and structural modifications. UV–Vis diffuse reflectance spectroscopy (DRS) revealed a redshift in absorption edges as CuS QDs content increased, enhancing visible light absorption. Photoluminescence (PL) investigations revealed that the 15 % CuS QDs@Fe MIL101 heterojunction had an effective charge separation and low recombination rates. The zeta potential analysis revealed a negative surface charge, indicating an overall electronegative characteristic. The photocatalytic performance, assessed through the degradation of MLX, demonstrated that the 15 % CuS QDs@Fe MIL101 heterojunction achieved the maximum degradation efficiency, reaching 96 % after 45 min of irradiation at a dosage of 0.1 g/L. This exceptional performance is attributed to potent charge separation, improving visible light absorption, high surface area and adsorption capacity. Various scavengers were used to investigate the roles of different reactive species, revealing holes as the predominant active species in the photocatalytic degradation process. These results highlight the potential of 15 % CuS QDs@Fe MIL101 heterojunctions as efficient photocatalyst for environmental remediation from pharmaceutical pollutants under simulated sunlight. These findings highlight the potential for application of CuS QDs@Fe MIL101 in real-world wastewater treatment systems, particularly in addressing pharmaceutical contaminants like meloxicam in industrial effluents.

A two-stage sorption strategy to improve heat storage performance of salt/porous matrix composites

Composites combining salt hydrates and porous matrix like metal–organic frameworks (MOFs) are used to enhance the performance of thermochemical storage materials. However, the mechanism for the enhancement and the strategy for the selection of salt hydrates and porous matrix are not clear. The heat storage performance is determined by water adsorption dynamics, capacity and their sorption energy of the single components. The single components (salts or matrix) normally have either fast water adsorption dynamics or high-water uptake capacity, but not both of them. In this study, we investigate the enhancement of adsorption in composite materials, and a novel strategy is then proposed to combine the advantages from adsorbents with higher adsorption dynamics at low water partial pressure with those with a high capacity at high water partial pressure to promote the water adsorption capacity and kinetics, hence efficient energy storage. Two types of composites have been used to demonstrate the two-stage strategy developed in this study, in which SrCl2 and SrBr2 are incorporated into MOF MIL-101(Cr) to enhance adsorption and heat storage. In these composites, SrCl2 and SrBr2 can be regarded as the moisture pumps, capturing water vapour from air to improve the adsorption dynamics, while MIL-101(Cr) with high adsorption capacity functions as a water reservoir to take the water accumulated by the salts. Through this two-stage design, the water sorption capacity of the composites is 2–3 times higher than the water uptake of either salts or MOF within 120 min. As SrCl2 has a faster water adsorption kinetics than SrBr2, SrCl2/MIL-101(Cr) reaches an uptake of 0.73 g/g, however, the water sorption capacity of SrBr2/MIL-101(Cr) is 0.54 g/g. The composite samples also present good heat storage capacities of 1462 J/g for SrCl2/MIL-101(Cr) and 1526 J/g for SrBr2/MIL-101(Cr), and good cycling stability after 15 repeating adsorption/desorption cycles.

Synergistic ionic liquid encapsulated MIL-101 (Cr) metal-organic frameworks for an innovative adsorption desalination system

The transformations of brackish water into freshwater employing porous materials such as metal-organic frameworks (MOFs) show a great potential for a green environment. But the adsorption-based desalination slows down due to slow water adsorption/desorption rates and inadequate water storage capacity in conventional adsorbents. Therefore, the restructuring of porous MOFs increases water storage and transfer rates. This paper presents a comprehensive investigation on the fabrication of ionic liquid encapsulated MIL-101 (Cr) MOFs (metal-organic frameworks), and its interactions with water for desalination applications. Firstly, the pristine MIL-101 (Cr) is encapsulated with various types/amounts of ionic liquids. Next, these MOFs are characterized via SEM (Scanning electron microscope), FTIR (Fourier transform infrared), XRD (X-ray diffraction), TGA (Thermal gravimetric analysis), N2 adsorption techniques. The water adsorption on these MOFs is performed experimentally for a wide temperature (30–80 °C) and pressure (0 < P/Ps < 0.95) ranges. The effects of the size (or type) as well as the encapsulation ratio of ionic liquids on water adsorption behaviors are conducted. Based on the experimentally proven water adsorption (isotherms and kinetics) data, an AD (adsorption desalination) system is modelled and simulated. Finally, the AD performances in terms of the specific daily water production (SDWP) and performance ratio (PR) are parametrically studied with respect to various regeneration temperature (50–80 °C) and cycle times (100 s–1000 s). It is found that by ionic liquid encapsulation, the water uptakes/offtake rates are expedited up to 48% (for adsorption)/55% (for desorption), respectively. In addition, the water transfer (Δq) improves up to 45% more than the parent MIL-101(Cr) MOFs. Furthermore, the SDWP increases from 38 to 56 m3 of water per tonne of MOFs per day at the regeneration temperature of 70 °C. The simulation results also show that the ionic-liquid-encapsulated MIL-101 (Cr) MOFs generates water (>25 m3 water per tonne of IL-MOFs) at the regeneration temperature of 50 °C and is potential for the next generation desalination applications.

Synergistic effect of oxygen vacancies and functionalized ligands selectively enhanced the photocatalytic oxidation of methane to carbon monoxide

The titanium-based metal–organic framework MIL-125(Ti) has been widely investigated in photocatalytic carbon dioxide reduction and water splitting, but rarely studied in photocatalytic methane conversion by employing only water as an oxidant under mild conditions. Simultaneously controlling products with high yield and selectivity is highly challenging in methane conversion. Herein, we develop a series of functionalized titanium metal–organic frameworks via a facile organic ligand exchange process. The abundant Ti3+ active sites induced by oxygen vacancies and functionalized ligands synergistically facilitate the adsorption and activation of methane molecules. The carbon monoxide yield over NH2-MIL-125(Ti) increased to 198.6 μmol·gcat−1·h−1 with a high selectivity of 87.1 % under simulated solar illumination. Combined with in-situ characterizations and density functional theoretical calculations, the results confirmed that Ti3+ active sites induced by oxygen vacancies and amino functional groups synergistically enhanced the photocatalytic conversion of methane and elucidate CH4-to-CO conversion mechanism. This study does not only provide insights into the rational design of metal–organic frameworks with copious oxygen vacancies and functional groups, but also provides some significant cognition for photocatalytic methane conversion.

Non-steroidal anti-inflammatory drugs adsorption from aqueous solution by MOFs MIL-100(Fe), ZIF-8 and UiO-66: Synthesis, characterization, and comparative study

Pharmaceutical products such as ibuprofen and naproxen pose a potencial risk to the environment and to the human health. In this context, it is necessary seek and implement new effective and low-cost technologies for water treatment such as adsorption. Metal-organic frameworks (MOFs) emerge as promising adsorbent materials due to their structural diversity and stability. The obtained MOFs were characterized by SEM/EDX, XRD, FTIR, N2 at 77 K, DLS, and PZC. According to the textural parameters, the obtained MOFs have the next surface areas: MIL-100 (Fe) 1359 m2, ZIF-8 357 m2 and UiO-66 1654 m2. Having this differences in surface areas, alongside the different PZC of each materials, affect the adsorption capacity. According to the experimental data UiO-66 and MIL-100(Fe) had the highest ibuprofen adsorption capacity (152.3 mg g-1) and naproxen adsorption capacity (278.3 mg g-1), respectively. On the other hand, ZIF-8 has the lowest adsorption capacity of ibuprofen and naproxen (85.4 and 78.9 mg g-1 respectively). It was found that the best-fitting model according to its R2 for all materials with both adsorbates was the Sips model. Moreover, all materials with all adsorbates, except for UiO-66 with naproxen, reached equilibrium within the first 120 min and fitted the pseudo-second order model. According to thermodynamic parameters and analysis of fitted kinetic models, it was determined that during adsorption, a combination of physical and chemical phenomena occurs, from which the following interactions are proposed as the main adsorption mechanisms: hydrogen bonding, π -π interactions, anion-π interactions, and Lewis’ acid/base interactions.

Capturing low-concentration benzene: Design and mechanism of high-performance Cu1-Ox,Ny-C single-atom adsorbents

Common adsorbents, such as active carbons, zeolites, and metal–organic frameworks (MOFs), struggle to capture low concentrations of benzene. Single-atom adsorbents (SAAs), boasting exceptional atomic utilization efficiency and precisely tailored electronic structures, offer a promising solution. This study first designed Cu1-Ox,Ny-C SAAs and explored their enhanced benzene adsorption through density functional theory (DFT). Particularly, a crucial link between the SA coordination configuration and its affinity for benzene was established. Next, Cu1-Ox,Ny-C was synthesized from the MOF MIL-101(Cr) and extensively characterized using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption fine structure (XAFS) spectroscopy, etc. to determine the coordination configuration of Cu single atoms. Finally, a thorough evaluation of the Cu1-Ox,Ny-C’ capacity and stability was conducted. Theoretical analysis revealed that Cu single atoms within the Ox,Ny-C matrix act as the primary adsorption sites for benzene. Notably, O and N atoms work synergistically: oxygen atoms promote adsorption, while nitrogen atoms mainly stabilize single-atom sites. Cu1-Ox,Ny-C was successfully synthesized, and characterization revealed that Cu1-O2,N2(trans)-C and Cu1-O3,N1-C were the dominant coordination configurations. Remarkably, despite a fourfold decrease in specific surface area compared to MIL-101(Cr), Cu1-Ox,Ny-C exhibited a threefold increase in chemisorption capacity for low-concentration benzene. Moreover, it exhibits excellent resistance to H2O and can be effectively reused. This study demonstrates a valuable strategy for designing and creating highly efficient SAAs for capturing low concentrations of benzene.

Unraveling the toluene adsorption mechanism of MIL-101(Cr) derived from PET waste for COV removal applications

Herein, we provide a study on the removal of volatile organic compounds (VOCs) using a metal-organic framework MIL-101(Cr) derived from PET waste, denoted as MIL-101(Cr)-PET. As a model molecule for VOCs frequently found in indoor air, toluene was used. The characteristics and adsorption efficiency of both conventional MIL-101(Cr), denoted as MIL-101(Cr)-BDC, and environmentally friendly MIL-101(Cr) powders were evaluated and compared using a range of techniques in our research, including PXRD, HAADF-STEM, TGA, BET, and adsorption studies. MIL-101(Cr)-PET exhibits crystal structure and thermal stability similar to the conventional MIL-101(Cr) synthesized using a commercially available organic linker. Differently, it displayed relatively agglomerated smaller particles and a reduced surface area, attributed to the absence of any modulator and the use of PET waste as the source of the organic linker. Nevertheless, similar toluene adsorption performance was obtained in both batch and continuous adsorption setups. Furthermore, the adsorption mechanism was elucidated by means of molecular simulation, identifying two distinct adsorption sites. At low toluene concentrations, the preferred site was within the small cage due to pore size constraints, while at saturation, the most likely conformation involved parallel offset staking. These results suggest the occupancy of less energetically favorable sites and volumetric filling at higher concentrations.

Modulating cell stiffness for improved vascularization: leveraging the MIL-53(fe) for improved interaction of titanium implant and endothelial cell

Vascularization plays a significant role in promoting the expedited process of bone regeneration while also enhancing the stability and viability of artificial bone implants. Although titanium alloy scaffolds were designed to mimic the porous structure of human bone tissues to facilitate vascularization in bone repair, their biological inertness restricted their broader utilization. The unique attribute of Metal-organic framework (MOF) MIL-53(Fe), known as “breathing”, can facilitate the efficient adsorption of extracellular matrix proteins and thus provide the possibility for efficient interaction between scaffolds and cell adhesion molecules, which helps improve the bioactivity of the titanium alloy scaffolds. In this study, MIL-53(Fe) was synthesized in situ on the scaffold after hydrothermal treatment. The MIL-53(Fe) endowed the scaffold with superior protein absorption ability and preferable biocompatibility. The scaffolds have been shown to possess favorable osteogenesis and angiogenesis inducibility. It was indicated that MIL-53(Fe) modulated the mechanotransduction process of endothelial cells and induced increased cell stiffness by promoting the adsorption of adhesion-mediating extracellular matrix proteins to the scaffold, such as laminin, fibronectin, and perlecan et al., which contributed to the activation of the endothelial tip cell phenotype at sprouting angiogenesis. Therefore, this study effectively leveraged the intrinsic “breathing” properties of MIL-53 (Fe) to enhance the interaction between titanium alloy scaffolds and vascular endothelial cells, thereby facilitating the vascularization inducibility of the scaffold, particularly during the sprouting angiogenesis phase. This study indicates that MIL-53(Fe) coating represents a promising strategy to facilitate accelerated and sufficient vascularization and uncovers the scaffold-vessel interaction from a biomechanical perspective.Graphical

Dimensionality Control of Li Transport by MOFs Based Quasi‐Solid to Solid Electrolyte (Q‐SSEs) for Li−Metal Batteries

AbstractNowadays, lithium‐ion batteries (LIBs) are widely used in all walks of life and play a very important role. As complex systems composed of multiple materials with diverse chemical compositions, where different electrochemical reactions take place, battery interfaces are essential for determining the operation, performance, durability and safety of the battery. This work, set out to study the incorporation of lithium bis(fluorosulfonyl)amide (LiFSI) doped 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm][TFSI]) ionic liquid into an archetype Ti‐based Metal Organic Framework (MOF) ((Ti) MIL125−NH2) to create a solid to quasi‐solid (depending on the amount of IL in the system), and how it affects not only ionic transport but also the structural properties of the IL/MOF electrolyte. Remarkably high ionic conductivity values (2.13×10−3 S ⋅ cm−1 at room temperature) as well as a lithium transference number (tLi=0.58) were achieved, supported by pulsed field gradient (PFG) NMR experiments. Electrochemical characterization revealed reversible plating‐stripping of lithium and lower overpotential after 750 h at 50 °C. Additionally, a proof‐of‐concept solid state battery was fabricated resulting in a discharge capacity of 160 mAh ⋅ g−1 at 50 °C and 0.1 C rate after 50 cycles. This work presents a suitable strategy to dendrite suppression capability, allowing its implementation as interface modifiers in next‐generation solid‐state batteries.

Rapid and selective removal of bisphenol S from environmental samples by surface-imprinted polymer synthesized based on metal-organic framework MIL-101(Cr)

In this study, a novel, surface-imprinted polymer (MIL-101@MIP) was successfully synthesized using the metal-organic framework MIL-101(Cr) with a large specific surface area as a carrier, which achieved rapid and selective removal of bisphenol S (BPS) from environmental samples. The structure and morphology of MIL-101@MIP were characterized using SEM, XPS, FTIR, TGA, BET, and XRD techniques. The results show that MIL-101@MIP has rough surface morphology and good thermal stability. The large specific surface area (1251.6 m2 g−1) of MIL-101@MIP provides more imprinting sites in MIL-101@MIP; thus, the maximum adsorption capacity of BPS reached 87.76 mg g−1 with good imprinting factor 2.08, and equilibrium was achieved in only 10 min. Moreover, the process of BPS adsorption onto MIL-101@MIP followed the pseudo-second-order kinetics and Langmuir isothermal adsorption models. In addition, the MIL-101@MIP was utilized as an adsorbent for a solid phase extraction column to determine BPS in seven environmental samples using HPLC, achieving recovery of 89.20–105.78%. The developed MIL-101@MIP is a promising and efficient adsorbent for rapid and selective removal of BPS from the environment.

Molecularly imprinted polymer based on MIL-101 (Cr) MOF incorporated polyvinylidene for selective adsorption and separation dye with improved antifouling properties

In this work, new membrane was fabricated from polyester fabric (PF) as a substrate which was coated by a casting solution containing polyvinylidene fluoride (PVDF) blending by addition of MIL-101 (Cr) metal-organic framework (MOF)-molecularly imprinted 3-aminophenolhexamethylenetetramine (MIAPH) as filler and sodium dodecyl sulfate (SDS) as hydrophilic agent. The membrane was fabricated by phase inversion method (PVDF/MIAPH). The MIAPH has selective functional groups and was applied as filler in the mixed matrix membrane. The as-prepared MIAPH was characterized by FE-SEM, EDS, XRD, FTIR and BET-BJH analyses. The hydrophilic property, dye adsorption and filtration properties of the MIAPH/PVDF/PF membrane were studied for removal Trypan blue (TB) based on central composite design (CCD) technique through investigating operational variables (pH, TB concentration, pressure). In the fabrication of membranes, the optimal filtration properties appear at the 30 μL of SDS solution and 0.005 g MIAPH fillers. The fabricated MIAPH/PVDF/PF membrane indicates a high removal efficiency up to 94.9 % for the TB removal and has high selectivity. The data of the adsorption equilibrium were described by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. The findings illustrated that appropriate of MIAPH in membranes could be an efficient and selective technique for TB elimination.

First Direct Gravimetric Detection of Perfluorooctane Sulfonic Acid (PFOS) Water Contaminants, Combination with Electrical Measurements on the Same Device—Proof of Concepts

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are pollutants of concern due to their long-term persistence in the environment and human health effects. Among them, perfluorooctane sulfonic acid (PFOS) is very ubiquitous and dangerous for health. Currently, the detection levels required by the legislation can be achieved only with expensive laboratory equipment. Hence, there is a need for portable, in-field, and possibly real-time detection. Optical and electrochemical transduction mechanisms are mainly used for the chemical sensors. Here, we report the first gravimetric detection of small-sized molecules like PFOS (MW 500) dissolved in water. A 100 MHz quartz crystal microbalance (QCM) measured at the third harmonic and an even more sensitive 434 MHz two-port surface acoustic wave (SAW) resonator with gold electrodes were used as transducers. The PFOS selective sensing layer was prepared from the metal organic framework (MOF) MIL-101(Cr). Its nano-sized thickness and structure were optimized using the discreet Langmuir–Blodgett (LB) film deposition method. This is the first time that LB multilayers from bulk MOFs have been prepared. The measured frequency downshifts of around 220 kHz per 1 µmol/L of PFOS, a SAW resonator-loaded QL-factor above 2000, and reaction times in the minutes’ range are highly promising for an in-field sensor reaching the water safety directives. Additionally, we use the micrometer-sized interdigitated electrodes of the SAW resonator to strongly enhance the electrochemical impedance spectroscopy (EIS) of the PFOS contamination. Thus, for the first time, we combine the ultra-sensitive gravimetry of small molecules in a water environment with electrical measurements on a single device. This combination provides additional sensor selectivity. Control tests against a bare resonator and two similar compounds prove the concept’s viability. All measurements were performed with pocket-sized tablet-powered devices, thus making the system highly portable and field-deployable. While here we focus on one of the emerging water contaminants, this concept with a different selective coating can be used for other new contaminants.

Postsynthetic Modification of Amine-Functionalized MIL-101(Cr) Metal-Organic Frameworks with an EDTA-Zn(II) Complex as an Effective Heterogeneous Catalyst for Hantzsch Synthesis of Polyhydroquinolines.

The present work aims at preparing the EDTA-Zn(II) complex-supported on the amine-functionalized MIL-101(Cr) MOF-as a new and effective heterogenized catalyst. The optimization of the hydrothermal process shows that 120 °C is the best condition to grow the MIL-101(Cr)-NH2 MOF crystals. Moreover, regarding the use of the postsynthetic modification (PSM) method, hexadentate EDTA was grafted on this support via a simple aminolysis process before further coordinating it with Zn ions to create the corresponding Zn(II) catalytic complex. The catalytic activity of this compound was then investigated in the context of a one-pot synthesis of polyhydroquinolines. This approach has a number of advantages including the following: the use of a solvent that is not hazardous, applying a porous catalyst that is inexpensive, secure, and recyclable; rapid reaction times, high levels of efficiency, and the simplicity of MOF catalyst separation. Accordingly, the process in question can be given the label of "green chemistry".

Sustainable conversion of polyethylene plastic bottles into terephthalic acid, synthesis of coated MIL-101 metal–organic framework and catalytic degradation of pollutant dyes

Persistent environmental colored compounds, resistant to biodegradation, accumulate and harm eco-systems. Developing effective methods to break down these pollutants is crucial. This study introduces Ag-MIL-101 (Ag-MIL-101) as a composite and reusable catalyst that efficiently degrades specific colored organic pollutants (COPs) like Methylene blue (MB), 4-Nitrophenol (4-NP), and 4-Nitroaniline (4-NA) using sodium borohydride at room temperature. The MIL-101 was synthesized using Terephthalic acid (TPA) derived from the degradation of Polyethylene Terephthalate (PET) plastic waste, with the assistance of zinc chloride. To further investigation, the kinetics of degradation reaction was studied under optimized conditions in the presence of Ag-MIL-101 as catalyst. Our results demonstrated the remarkable efficiency of the degradation process, with over 93% degradation achieved within just 8 min. The catalyst was characterized using FTIR, XRD, FESEM, and TEM. In this study, the average particle size of Ag-MIL-101 was determined using SEM and XRD analysis. These methods allow us to accurately and precisely determine the particle size. We determined the reaction rate constants for the degradation of each COP using a pseudo first-order kinetic equation, with values of 0.585, 0.597 and 0.302 min−1 for MB, 4-NP, and 4-NA, respectively. We also evaluated the recyclability of the catalyst and found that it could be reused for up to three cycles with only a slight decrease in efficiency (10–15%). Overall, our findings highlight the promising application of Ag-MIL-101 as an effective catalyst for the degradation of COPs, emphasizing the importance of optimizing reaction conditions to achieve enhanced efficiency.