Amino-functionalized Metal-organic Framework Research Articles

Degradation of Orange G Using PMS Triggered by NH2-MIL-101(Fe): An Amino-Functionalized Metal-Organic Framework.

As an azo dye, OG has toxic and harmful effects on ecosystems. Therefore, there is an urgent need to develop a green, environmentally friendly, and efficient catalyst to activate peroxymonosulfate (PMS) for the degradation of OG. In this study, the catalysts MIL-101(Fe) and NH2-MIL-101(Fe) were prepared using a solvothermal method to carry out degradation experiments. They were characterized by means of XRD, SEM, XPS, and FT-IR, and the results showed that the catalysts were successfully prepared. Then, a catalyst/PMS system was constructed, and the effects of different reaction systems, initial pH, temperature, catalyst dosing, PMS concentration, and the anion effect on the degradation of OG were investigated. Under specific conditions (100 mL OG solution with a concentration of 50 mg/L, pH = 7.3, temperature = 25 °C, 1 mL PMS solution with a concentration of 100 mmol/L, and a catalyst dosage of 0.02 g), the degradation of OG with MIL-101(Fe) was only 36.6% within 60 min; as a comparison, NH2-MIL-101(Fe) could reach up to 97.9%, with a reaction constant k value of 0.07245 min-1. The NH2-MIL-101 (Fe)/PMS reaction system was able to achieve efficient degradation of OG at different pH values (pH = 3~9). The degradation mechanism was analyzed using free-radical quenching tests. The free-radical quenching tests showed that SO4•-, •OH, and 1O2 were the main active species during the degradation of OG.

Coupling chemical modification and immobilization of cellulase improves thermal stability and low-melting mixture solvent tolerance for in situ saccharification of bagasse

In situ saccharification of lignocellulosic biomass in low-melting mixture solvents (LoMMSs) is a promising approach for biorefinery. In this study, chemical modification of cellulase coupled with immobilization was designed to improve thermal stability and LoMMS tolerance of cellulase for in situ saccharification. Cellulase was firstly chemically modified with succinic anhydride and ethylenediamine respectively to form succinylated cellulase (S-Ce) and aminated cellulase (A-Ce), then the modified cellulases were immobilized with amino-functionalized metal-organic frameworks to establish ZIF-8/A immobilized A-Ce and S-Ce. Circular dichroism, fluorescence measurements, X-ray diffraction, fourier transform infrared spectra and scanning electron microscopy were applied to characterize the modified cellulase or immobilization carrier. ZIF-8/A immobilized A-Ce presented desired thermal stability and LoMMS tolerance. Reducing sugar yields via ZIF-8/A immobilized A-Ce during in situ saccharification of bagasse maintained stably till Bet/AA concentration reached 50%, and declined relatively slowly compared with free or other immobilized cellulase when Bet/AA concentration further increased to 90%. In situ saccharification of bagasse via ZIF-8/A immobilized A-Ce in concentrated Bet/AA (50%) can be operated at a wide temperature range (50–60 °C). The corresponding reducing sugar yield with ZIF-8/A immobilized A-Ce was 58% higher than that with free cellulase in 50% Bet/AA at 60 °C.

Carbon quantum dots/UiO-66@polysulfone porous microspheres fabricated via pickering emulsion template for pollutant removal

The advancement of sophisticated photocatalytic materials for environmental amelioration has become increasingly imperative in the context of persistent organic pollutants in aqueous effluents. The amalgamation of metal-organic frameworks (MOFs) with nanocomposite constituents has demonstrated promising prospects in augmenting photocatalytic efficiency. Nevertheless, obstacles persist in the realms of optimizing photon absorption and the segregation of electron-hole pairs. The application of carbon quantum dots (CQDs) within this sphere, particularly in synergy with amino-functionalized MOFs such as UiO-66-NH2, remains underexplored. In this study, we elucidate the synthesis of UiO-66@Polysulfone porous microspheres, augmented by CQDs, employing an innovative Pickering emulsion template approach for the photocatalytic degradation of tetracycline. Our findings reveal that this composite material not only manifests a distinctive hollow microsphere architecture, contributing to an elevated specific surface area, but also markedly enhances the degradation efficacies of both methylene blue and tetracycline under visible light irradiation. Moreover, this research accentuates the material's exceptional recyclability and stability, highlighting its potential as a sustainable and efficacious solution for the remediation of wastewater and organic pollutant degradation.

Molecularly imprinted sensor based on cascade enzyme system supported by metal-organic framework (UiO-66-NH2) for sensitive colorimetric detection of cholesterol

Cholesterol is a crucial cellular molecule in the human body, and a neutral lipid necessary for maintaining the integrity and fluidity of cell membranes. Additionally, it acts as a precursor for the synthesis of essential substances for living organisms, including steroid hormones, bile acids and vitamins. Nonetheless, cholesterol is not always advantageous, and both excess and deficiency of cholesterol can result in serious diseases. Therefore, maintaining cholesterol at a normal level is of paramount importance for the maintenance of normal cellular activity. In this study, an amino-functionalized metal-organic framework (UiO-66-NH2, abbreviated as U6NH2) was used as a carrier, on the surface of which gold nanoparticles (AuNPs) was embedded and cholesterol oxidase (ChOx) was immobilized, and then cholesterol was employed as a template molecule, followed by the synthesis of molecularly imprinted polymers (MIPs). Remarkably, the obtained U6NH2@AuNPs-ChOx@MIPs can be used to facilitate efficacious and selective detection of blood cholesterol through a facile colorimetric method over a range of 2.9 mM - 6.7 mM with a limit of detection (LOD) = 2.4 mM, while the normal level of blood cholesterol should be less than 5.18 mM. Moreover, the sensing system demonstrates excellent stability and satisfactory selectivity. The constructed cholesterol selective detection system reported in this paper is anticipated to have a crucial impact on bioanalysis.

Effect of amino functional groups on the surface properties and Lewis's acid base parameters of UiO-66(NH2) by inverse gas chromatography

Amino-functionalized metal organic frameworks (MOFs) have attracted much attention for various applications such as carbon dioxide capture, water remediation and catalysis. The focus of this study is to determine the surface and Lewis's acid-base properties of UiO-66(NH2) crystals by the inverse gas chromatography (IGC) technique at infinite dilution. The latter was applied to evaluate the dispersive component of the surface energy γsd(T) by using thermal model and several molecular models. The obtained results proved that γsd(T) decreases when the temperature increases. The best results were achieved by using the thermal model that takes into account the effect of the temperature on the surface areas of the organic molecules. We also observed a decrease of the Gibbs surface free energy of adsorption by increasing the temperature of the different organic solvents. The polar interactions of UiO-66(NH2) were obtained by using the methods of Saint-Flour Papirer, Donnet et al., Brendlé-Papirer and the different molecular models. The Lewis's acid base constants KA and KD were further calculated by determining the different variables of adsorption of the probes on the solid surface and the obtained values were 1.07 and 0.45 for KA and KD respectively, with an acid-base ratio (KA/KD) of 2.38. These values showed the high acidic surface of the solid substrate; whereas, the values of the entropic acid base parameters, ωA, ωD and ωA/ωD respectively equal to 1.0×10−3, 3.8×10−4 and 2.73, also highlighted the important acidity of UiO-66-(NH2) surface. These important findings suggest that the surface defects (missing linkers and/or clusters) in UiO-66(NH2) are the main determining factor of the acid-base properties of UiO-66 based structures.

Metal-organic framework-decorated PTFE reinforced membranes with immobilized caffeic acid radical scavenger towards improved performance and durability of PEMFC

During the continuous operation of fuel cell, the generated free radicals have an irreversible effect on the proton exchange membrane (PEM), and the introduction of free radical scavengers is an effective strategy for improving its durability. In this study, we proposed to prepare thin and highly durable reinforced membranes by immobilizing organic radical scavenger caffeic acid on the fibrous PTFE supporting layer decorated with amino-functionalized metal-organic framework. The electrostatic force between the amino and sulphonic acid groups can induce an orderly aggregation of hydrophilic cationic groups within the Nafion, endowing the reinforced composite PEMs with superior proton conductivity. The mechanical properties and dimensional stability of the reinforced membranes were effectively enhanced by the reinforcement of the PTFE layer decorated with the MOF network, and the hydrogen crossover was mitigated. The thickness of Nafion reinforced membranes was reduced to 25 µm with the PTFE reinforcement. After assembling in a single cell, the Nafion composite membrane (PPUC-Nafion-3) with a 3 wt% doping of caffeic acid achieved a maximum power density (PDmax) of 812.64 mW cm−2 and the open circuit voltage (OCV) decay rate of only 1.11 mV h−1 over 100 h. For comparison under the same conditions, recast Nafion possessed a much lower PDmax of only 486.30 mW cm−2 and a higher OCV decay rate of 1.91 mV h−1. This study demonstrates an effective approach to developing highly durable and thin PEMs for the realization of PEMFC with improved output performance and durability simultaneously.

The role of mixed ligand approach in enhancing catalytic activity of copper-based MOFs in knoevenagel condensation

The stability and catalytic activity of the amino-functionalized metal-organic frameworks based on Cu were tested in an organic reaction, Knoevenagel condensation. By utilizing different ratios of benzene-1,4-dicarboxylic acid (H2BDC) and 2-amino-benzene-1,4-dicarboxylic acid (NH2-BDC), the amine content was modulated for the synthesis. The amino-based MOFs synthesized with the 1 to 2, 2 to 1, and 1 to 1 ratio of BDC and NH2-BDC that NH2(33%)-Cu-MOF showed the best catalytic performance. The optimum balance between the amount of pore size and the basic amine sites of the framework was provided by this ratio. Also, the activity of catalysts was tested for various substrates' electron-withdrawing and electron-donating groups. Further analyses proved the stability of the NH2(33%)-Cu-MOF. After the catalysis process, the catalyst remained crystalline, and the stability of the framework was proved by PXRD patterns, proving it readily regenerated for the next cycle. Also, the catalytic mechanism has been checked.

Amino functionalized metal–organic framework as eco-friendly support for enhancing stability and reusability of horseradish peroxidase for phenol removal

Amino functionalized metal–organic framework as eco-friendly support for enhancing stability and reusability of horseradish peroxidase for phenol removal

A “turn off” sensor for highly sensitive and selective detection of syringaldehyde typed aromatic aldehydes based on an amino-functionalized metal–organic framework

Aromatic aldehydes are important chemical raw materials with serious harm to human health and environment. Sensitive, selective and rapid detection of these compounds is of great significance. However the facile fluorescence detection of aromatic aldehydes in aqueous solution is still challenging. Herein, the solvothermal synthesis of a NH2-BDC-Tb-MOF using Tb3+ ion and 2-aminoterephthalic acid (NH2-BDC) ligand was reported. This MOF can be used as a rapid response fluorescence sensor for highly sensitive, selective and rapid detection of syringaldehyde typed aromatic aldehydes in aqueous solution. The limit of detection can reach 0.69 μM, which was comparable with most of the reported fluorescence sensors for aromatic aldehydes. The selective detecting mechanism towards syringaldehyde typed aromatic aldehydes was also discussed in the paper.

One-pot solvothermal synthesis of In-doped amino-functionalized UiO-66 Zr-MOFs with enhanced ligand-to-metal charge transfer for efficient visible-light-driven CO2 reduction

Metal organic frameworks (MOFs) with high porosity and highly tunable physical/chemical properties can serve as heterogeneous catalysts for CO2 photoreduction, but the application is hindered by the large band gap (Eg) and insufficient ligand-to-metal charge transfer (LMCT). In this study, a simple one-pot solvothermal strategy is proposed to prepare an amino-functionalized MOF (aU(Zr/In)) featuring an amino-functionalizing ligand linker and In-doped Zr-oxo clusters, which enables efficient CO2 reduction driven with visible light. The amino functionalization leads to a significant reduction of Eg as well as a charge redistribution of the framework, allowing the absorption of visible light and the efficient separation of photogenerated carriers. Furthermore, the incorporation of In not only promotes the LMCT process by creating oxygen vacancies in Zr-oxo clusters, but also greatly lowers the energy barrier of the intermediates for CO2-to-CO conversion. With the synergistic effects of the amino groups and the In dopants, the optimized aU(Zr/In) exhibits a CO production rate of 37.58 ± 1.06 μmol g-1 h−1, outperforming the isostructural University of Oslo-66- and Material of Institute Lavoisier-125-based photocatalysts. Our work demonstrates the potential of modifying MOFs with ligands and heteroatom dopants in metal-oxo clusters for solar energy conversion.

Ratio fluorescence test strip visualized by amino-functionalized metal–organic framework for rapid sensing of glyphosate

As glyphosate is a broad-spectrum herbicide extensively used in agriculture worldwide, rapid glyphosate detection is essential for food safety and human health. Herein, a ratio fluorescence test strip was prepared and coupled with an amino-functionalized bismuth-based metal–organic framework (NH2-Bi-MOF) that bonded with copper ion for rapid visualization and determination of glyphosate. NH2-Bi-MOF had excellent fluorescence performance, and the copper ion, a Lewis acid, was selected as the quencher. The strong chelation of glyphosate with copper ion and its quick interaction with NH2-Bi-MOF would turn on the fluorescence signal, thus enabling the quantitative sensing of glyphosate, with a linear range of 0.10–200 µmol L−1, and recoveries between 94.8% and 113.5%. The system was then expanded to a ratio fluorescence test strip, in which the fluorescent ring sticker was set as a binding-in self-calibration to reduce errors from the angle and light dependency. The method realized the visual semi-quantitation referring to a standard card, as well as the ratio quantitation using the gray value output with LOD of 0.82 µmol L−1. And the as-developed test strip was accessible, portable, and reliable, thus offering a platform for the rapid on-site detection of glyphosate and other residual pesticides.

Kinetics of Guest-Induced Structural Transitions in Metal–Organic-Framework MIL-53(Al)-NH2 Probed by High-Pressure Nuclear Magnetic Resonance

A nuclear magnetic resonance (NMR) study of a pore opening in amino-functionalized metal-organic framework (MOF) MIL-53(Al) in response to methane pressure variation is presented. Variations of both NMR signal intensities and transversal relaxation rates for methane are found to reveal hysteretic structural transitions in the MOF material, which are smeared out over broad pressure ranges. Experiments with pressure reversals upon an incomplete adsorption/desorption gave deeper insight into the microscopic transition mechanisms. These experiments have unequivocally proven that the non-stepwise pore opening/closing transitions observed in the experiments are governed by a distribution of the opening/closing pressures over different MOF crystallites, for example, due to a distribution of the crystal sizes or shapes. The slow kinetics of the structural transitions measured in the hysteresis regime revealed a complex free energy landscape for the phase transition process.

Synergistic Utilization of a CeO2-Anchored Bifunctionalized Metal–Organic Framework in a Polymer Nanocomposite toward Achieving High Power Density and Durability of PEMFC

The free radicals produced during the long-term operation of fuel cells can accelerate the chemical degradation of the proton exchange membrane (PEM). In the present work, the widely used free radical scavenger CeO2 was anchored on amino-functionalized metal–organic frameworks, and flexible alkyl sulfonic acid side chains were tethered onto the surface of inorganic nanoparticles. The prepared CeO2-anchored bifunctionalized metal–organic framework (CeO2-MNCS) was used as a promising synergistic filler to modify the Nafion matrix for addressing the detrimental effect of pristine CeO2 on the performance and durability of PEMs, including decreased proton conductivity and the migration problem of CeO2. The obtained hybrid membranes exhibited a high proton conductivity up to 0.239 S cm–1, enabling them to achieve a high power density of 591.47 mW cm–2 in a H2/air PEMFC single cell, almost 1.59 times higher than that of recast Nafion. After 115 h of acceleration testing, the OCV decay ratio of the hybrid membrane was decreased to 0.54 mV h–1, which was significantly lower than that of recast Nafion (2.18 mV h–1). The hybrid membrane still maintained high power density, low hydrogen crossover, and unabated catalytic activity of the catalyst layer after the durability test. This study provides an effective one-stone-two-birds strategy to develop highly durable PEMs by immobilizing CeO2 without sacrificing proton conductivity, allowing for the realization of improvement on the performance and sustained durability of PEMFC simultaneously.

Two Birds, One Stone: Coupling Hydrogen Production with Herbicide Degradation over Metal–Organic Framework-Derived Titanium Dioxide

Consumption of contaminated water can have detrimental effects on the health of every living organism on earth. There is, thus, a need to develop novel materials and technologies to purify water. Water is also a source of hydrogen, a clean renewable fuel that can be generated through the action of a photoactive catalyst and the earth’s abundant solar energy. Using photocatalysis, we can purify water by removing organic pollutants through the photodegradation reaction (oxidation) and produce hydrogen (H2) through the hydrogen evolution reaction (reduction). However, we can combine these two reactions in a single process to achieve an efficient photocatalytic system. Herein, we report the dual-functional photocatalysis (DFP) on herbicide-contaminated water using TiO2 polymorphs derived from the amino-functionalized metal–organic framework (MOF), MIL-125-NH2. Heteroatom TiO2 doping led to the generation of N- and N,S-doped TiO2. Of all the pristine and doped TiO2 phases synthesized, the N,S-doped anatase (NSTA) was the best dual-functional photocatalyst in degrading glyphosate (PMG) with simultaneous H2 production at a rate of 660 μmol g–1 h–1. Nuclear Magnetic Resonance studies indicate the preferential cleaving of PMG’s C–N bonds, here referred to as α and β C–N bonds, leading to the formation of glycine, formic acid, and phosphoric acid as the major degradation products. Density functional theory calculations indicate PMG’s activation through the carboxy and phosphoric acid groups on the surface of NSTA and through the phosphoric acid group on the surface of TiO2-rutile. Our results suggest that the catalytic activity of NSTA can be attributed to the templated impact of the parent MOF, owing to its porosity, redshifting of the band absorption edge toward the visible region, reduced energy bandgap, surface defects, and the presence of oxygen vacancies. The binding mode of PMG to NSTA and its degradation allowed us to test the photodegradation of other herbicides, such as glufosinate ammonium and 2,4-dichlorophenoxyacetic acid. Interestingly, our MOF-derived NSTA proved to be active in purifying water when all three herbicides were combined and produced H2 with a rate of 329 μmol g–1 h–1 simultaneously.

Immobilizing Isatin-Schiff Base Complexes in NH2-UiO-66 for Highly Photocatalytic CO2 Reduction

Reducing carbon dioxide (CO2) via photocatalysis to carbon-based materials is a challenging process due to the complexity of the process and the production of several byproducts. Therefore, it is crucial to develop photocatalysts with high yield and selectivity for CO2 reduction. Herein, we present a strategy for creating high-performance catalysts by immobilizing Ni, Co, and Cu ions in NH2-UiO-66 by covalently linking the isatin-Schiff base metal complexes (IS) to the micropores. The as-synthesized NH2-UiO-66/IS-complex (66-IS-M, M = Ni, Co, Cu) photocatalysts exhibit special photocatalytic activity for the reduction of CO2 because of the immobilized metal ions serving as active sites during the reaction. Among them, 66-IS-Ni has a maximum CO generation rate of 1350 μmol g–1 h–1 and a CO selectivity of 87%, both of which are significantly higher than those of previously reported metal–organic framework (MOF)-based photocatalysts. Experimental characterizations and density functional theory (DFT) calculations reveal that the effective charge separation and lowered free energy of CO2 reduction on 66-IS-Ni promote CO2 conversion. This study presents a universal strategy for the uniform dispersion of molecular catalysts in amino-functionalized MOF for efficient photocatalytic applications.

Novel amino-functionalized Ni(II)-based MOFs for efficiently photocatalytic reduction of CO2 to CO with superior selectivity under visible-light illumination

Metal-organic frameworks (MOFs) have aroused ever-growing scientific interest for photocatalytic CO2 reduction reaction (CO2RR). Delicate design and synthesis of MOFs with open metal sites (OMSs) is the key to activate CO2 and even stabilize the reaction intermediates of CO2RR, further determine the superior selectivity. Herein, two amino-functionalized MOFs (Ni-Bpyb and Ni-Bipy) with open Ni(II) sites were constructed from 2′-amino-5′-(4-carboxyphenyl)-[1,1′:3′,1″-terphenyl]-4,4″-dicarboxylic acid (NH2-BTBH3) and different lengths of linear N-donor linkers, 1,4-bis(4-pyridyl) benzene (Bpyb) or 4,4′-bipyridine (Bipy). Under visible-light irradiation, Ni-Bpyb shows more excellent CO yield of 1326.7 μmol·g−1·h−1 with impressive apparent quantum efficiency (AQE, 2.12 %@420 nm) and selectivity (98.80 %). Significantly, this AQE value is at the high end among MOFs-based photocatalysts for CO2RR. The reaction mechanism has been carefully investigated by experimental and theoretical calculations results. Photoelectric experiments demonstrate that Ni-Bpyb shows higher electron–hole separation efficiency compared to Ni-Bipy. Theoretical calculations validate that the open Ni(II) sites of Ni-Bpyb possess lower energy barriers of CO2 adsorption and reducing CO2* to COOH*, as well as better stabilizes COOH* intermediate than those of Ni-Bipy. These merits synergistically contribute to the superior performance and selectivity of Ni-Bpyb. This work might give a guidance for the design of efficient MOFs-based photocatalysts with excellent selectivity for CO2RR.

Determination of cadmium in rice samples using amino-functionalized metal-organic framework by a pipette tip solid phase extraction

In this study, the amino-functionalized metal-organic framework (NH2-MOFs) was used as an adsorbent for the extraction of cadmium in rice samples based on the pipette tip solid phase extraction (PT-SPE) before determined by the flame absorption spectrometry (F-AAS). The pH of the sample solution, initial concentration of the cadmium, the volume of the sample, elution ‎conditions, and the amount of adsorbent on the recovery of the cadmium were investigated and ‎optimized. The results showed that the best extraction efficiency of cadmium was obtained at pH 5.0, 2500.0 µL of cadmium solution, and 20.0 ‎µL of HCl (10% V/V) ‎ as eluent solvent. First, the cooking rice was transferred to a beaker and hydrochloric acid/nitric acid was added to it as a digestion process before analysis by the PT-SPE procedure. The limit of detection of this method was found to be 0.03 µg L-1 with a relative standard deviation of ≤ 2.5 % (for seven replicate analyses of 50 µg L-1 of cadmium). The linear and dynamic ranges were achieved at 0.3 -14.5 µg L-1 and 0.3 -150 µg L-1, respectively. The adsorption capacity of sorbent and enrichment factor was 175 mg g-1 and 125 folds, respectively.

Comparative effects of the pristine and amino-functionalized metal–organic frameworks on the mechanical properties and microstructures of cement pastes

The present work investigated the effects of MIL-101(Fe) and its amino-functionalized counterpart NH2-MIL-101(Fe) on the mechanical properties, hydration processes and microstructure of cement pastes. Results showed that the addition of 0.05 wt% of these two kinds of metal–organic frameworks (MOFs) enhanced the 28-day compressive strength of cement pastes by 39.32% and 30.27%, respectively. Meanwhile, X-ray diffraction revealed that two MOFs exhibited different stability behaviors in alkaline simulated cement pore solutions. In addition, the hydration heat experiments disclosed that prepared MOFs expedited the hydration process of the Blank group by about 1 h and increased the hydration degree. Mercury intrusion porosimetry results showed that the employed MOFs could refine pore size, increase gel porosity and optimize pore structure. Furthermore, the formation of Ca-BDC complexes in MIL-101(Fe)-doped cement composites promoted the hydration process and then enhanced the compressive strength. Also, the formation of Ca-BDC was further confirmed based on density functional theory calculations.

Inner filter effect on amino-functionalized metal-organic framework for the selective detection of tetracycline

The use of tetracycline (TC) for the treatment of infectious diseases caused by bacteria has been humongous over the past few decades. However, the presence of untreated TC in freshwater leads to antimicrobial resistance. To prevent this concern from damaging the freshwater system, a stable sensor with high selectivity and rapid detection towards TC is desirable. Metal-Organic Frameworks (MOFs) are organic-inorganic hybrid structures with excellent stability, multifunctional ability, and tuneable pore structure that find extensive applications in detection techniques. The structural adaptability, excellent porosity and large surface area of MOFs prove advantageous in terms of adsorption of antibiotics. With this insight, a highly stable Zn-based Luminescent Metal-Organic Framework (LMOF) for the selective detection of tetracycline was developed. It is worth mentioning that, the LMOF-based sensor showed no depreciation in luminescence activity and can be reused more than 10 times. Moreover, a very low detection limit of 0.11 μM and a Stern-Volmer quenching constant (Ksv) value of 1.16 × 104 M−1 indicate its sensitivity precision towards TC detection. A significant inner filter effect of TC was observed in addition to adsorption of TC on the MOF through hydrogen bonding. Further, test strips based on IRMOF-3 showed satisfactory recovery in real-time samples. Thus, the stimuli-responsive sensor reports a simple strategy for excellent sensing performance towards TC.

Highly efficient adsorption desalination employing protonated-amino-functionalized MOFs

The MOFs (metal organic frameworks) namely MIL-101 (Cr), MIL-125 (Ti) and UiO-66 (Zr) are found suitable for desalination and cooling applications. To improve both cooling and desalination performances, these MOFs were embedded with amino (–NH2) functional groups. For further improvement of water adsorption capacity and rates, the amino-functionalized MOFs can be protonated with hydrochloric acid (HCl). This article at first deals with the synthesis and characterization of protonated-amino-functionalized (NH3+Cl−) MIL-101 (Cr), MIL-125 (Ti) and UiO-66 (Zr) MOFs. Secondly, under adsorption and desorption conditions, the H2O loadings on these adsorbents are evaluated from transient to steady states. The experimental results show that the protonation (NH3+Cl−) based MIL-101 (Cr), MIL-125 (Ti) and UiO-66 (Zr) MOFs show the greater water distribution of 0.35, 0.31 and 0.4 kg/kg of MOFs. According to experimental results (heat exchanger performance, adsorption isotherms and kinetics data), the performance criteria such as specific cooling capacity (SCP), daily water production (SDWP) and coefficient of performance (COP) are evaluated for various desorption temperature (60 to 80°C) and cycle time (100 to 1000 s). The simulation results show a remarkable improvement in water production i.e., SDWP > 50 m3 desalinated water/t of adsorbents/day for protonated UiO-66 (Zr) MOFs. Additionally, the SCP improves from 0.006 to 0.72 kW/kg of MOFs.