Chromium-based Metal-organic Framework Research Articles

Chromium-based metal-organic framework, MIL-101 (Cr), assisted hydrothermal pretreatment of teff (Eragrostis tef) straw biomass

Teff (Eragrostis tef) is a staple crop and holds the biggest share of grains cultivated area in Ethiopia, consequently, a large quantity of Teff straw is produced. The Teff straw was pretreated for the first time with Chromium-based Metal-Organic Framework, MIL-101(Cr), assisted hydrothermal method at temperatures ranging from 160 to 240 °C for 1/2, 1, or 2 h time independently. With an increase of pretreatment severity, the yield of total reducing sugar (TRS) was increased until reaching maximum (185 mg g−1). The identified optimum hydrothermal pretreatment condition, (180 °C and 1 h), had a feature of higher TRS yield and lower furfural concentration. The morphological analysis showed that treated Teff straw had degraded structure, higher surface area, and distorted bundles than native Teff straws. This study insight into MOFs’ application in lignocellulose biomass processing, and optimizing the pretreatment condition of Teff straw biomass.

Green Synthesis of MIL-88B(Cr) with the Co-Modulator of Nitric Acid and Acetic Acid

MIL-88B(Cr) is a prototypical flexible chromium-based metal-organic framework (MOF), which possesses extremely strong water/thermal stability and excellent “swelling/breathing” ability. However, in previous studies, there have been very few reports on MIL-88B(Cr) due to unclear synthesis details. Here, we found that the pure MIL-88B(Cr) can be facile synthesized through a hydrothermal method with the co-use of nitric acid and acetic acid (molar ratio = 1:15). The obtained MIL-88B(Cr) was sufficiently characterized by diverse techniques to assure its high-level quality. This work emphasizes a future valuable approach to expanding the production of flexible Cr-based MOF.

MIL-101-NH2-TFR and MIL-101-NH2-TFR/Cu2+ as novel hybrid materials for efficient adsorption of iodine and reduction of Cr(VI)

Today, due to the earnest jeopardies of environmental contaminants from various sources and their deteriorating effects on the ecosystem, the adsorption and reduction of these highly toxic pollutants with an efficient and cost-effective protocol can be considered a desirable phenomenon. Herein, a chromium-based metal-organic framework (MIL-101-NH2) was modified with thiourea and formaldehyde to form a polymeric layer on the surface (MIL-101-NH2-TFR). The resulting nanohybrid, as an adsorbent, was applied for efficient capture of iodine (I2) molecules from cyclohexane solution. MIL-101-NH2-TFR nanohybrid signified a superior adsorption performance for the capture of I2, compared to the pristine MIL-101-NH2, with a theoretical maximum uptake value of 625 mg/g and adsorption efficiency of 96.9 % through thionyl (CS), amino, and phenyl groups. The pseudo-second-order rate equation and the Langmuir model were best fitted for the I2 adsorption over MIL-101-NH2-TFR adsorbent. Quantum chemical calculations were conducted to reveal the mechanism of I2 adsorption onto the surface of MIL-101-NH2-TFR. Moreover, MIL-101-NH2-TFR was used to anchor Cu2+ to generate a catalytic system (MIL-101-NH2-TFR/Cu2+) for detoxification of Cr(VI) in the presence of formic acid as an eco-friendly reducing reagent in an aqueous medium. MIL-101-NH2-TFR and MIL-101-NH2-TFR/Cu2+ were reused several times for the adsorption/desorption process and the catalytic reduction, respectively.

A smartphone-assisted optosensingplatform based on chromium-based metal-organic framework signal amplification for ultrasensitive and real-time determination of oxytetracycline.

Ultrasensitive and onsite detection of oxytetracycline (OTC) is of vital significance for ensuring public health. Herein, a novel and versatile fluorescence biomimetic nanosensor, Mg,N-CDs@MIL-101@MIP, was elaborately tailored for the assay of OTC. MIL-101 with extraordinarily high surface area and porosity, as a favorable supporter, suppressed self-quenching of Mg,N-CDs and boosted mass transfer rate, realizing signal amplification. As an ultrasensitive signal transducer, high luminescent Mg,N-CDs yielded conspicuous fluorescence responses for OTC, enhancing the sensitivity of Mg,N-CDs@MIL-101@MIP. High-affinity imprinting sites further endowed Mg,N-CDs@MIL-101@MIP with superior anti-interference ability and reusability. Given prominent merits, Mg,N-CDs@MIL-101@MIP demonstrated a good linear range (0.05-40μgmL-1) with a lower limit of detection (16.8ngmL-1), supplying high accessibility to realize ultrasensitive and highly selective measurement of OTC in samples. Additionally, to attain precise onsite profiling of OTC, an intelligent sensing platform was developed by integrating Mg,N-CDs@MIL-101@MIP with a portable smartphone-assisted optical device. As both signal reader and analyzer, smartphone can instantly capture concentration-dependent fluorescent images and accurately digitize them, accomplishing quantitative analysis of OTC. More delightfully, the portable platform was utilized for visual determination of OTC in milk samples with satisfactory results, offering a promising tool for the high-performance onsite evaluation of food safety and environmental health.

Efficiently improving the adsorption capacity of the Rhodamine B dye in a SO3H-functionalized chromium-based metal–organic framework

A maximum adsorption capacity of 811.7 mg g−1 was achieved for RhB onto BUT-8(Cr).

Chromium-based metal-organic framework coated separator for improving electrochemical performance and safety of lithium-ion battery

To improve the electrochemical performance and safety of the traditional polymer separator, two kinds of chromium-based MOFs (Cr-MOFs) (namely MIL-88B(Cr) and MIL-101(Cr)) were studied as separator coatings. Compared with inorganic coating (Al2O3), Cr-MOFs coated separators exhibited improved thermal stability, better flame retardance, superior electrolyte wettability, high electrolyte uptake, good ionic conductivity and enhanced electrochemical performance. Moreover, although MIL-88B(Cr) and MIL-101(Cr) have the same metal center (Cr3+) and organic ligand (1,4-benzene dicarboxylate), their improvements on the performance of coated separators are obvious different. The detailed analyses reveal that the specific surface area, pore size and structure stability of Cr-MOFs are the main factors that affect their performances. The result of this work provides an essential basis for developing high performance separators with MOFs.

Nanoporous Ethylenediamine-Functionalized Metal–Organic Framework MIL-101 for the Removal of Proteins and Antipsychotic Drugs from Serum Samples

The development of functional materials for efficient protein removal and antipsychotic drug extraction in biological samples is attracting great interest. In this study, a nanoscale ethylenediamine-functionalized chromium-based metal–organic framework (MOF) (MIL-101-ED) was designed, synthesized, and applied for the one-step removal of proteins and the extraction of antipsychotic drugs in serum samples. The introduction of ethylenediamine in the MIL-101 nanoparticle (NP), in which amino and carbon chains can enhance the hydrogen-bond interaction and π–π interaction between functionalized MOFs and antipsychotic drugs, i.e., risperidone, etc. The antipsychotic drugs were ionized and amino groups were protonated at pH = 3, due to electrostatic interaction, and the negatively charged drugs were adsorbed on the surface or even entered the pores of MOFs. The adsorption efficiencies of the six kinds of drugs ranged from 80.1 to 101.4%. Owing to the exclusion action, proteins were excluded from MIL-101-ED and the exclusion rate ranged from 91.9 to 94.0%. Furthermore, MIL-101-ED can be easily regenerated and reused four times without a significant reduction in the protein exclusion rate and adsorption capacity. Coupled with high-performance liquid chromatography–diode array detection (HPLC–DAD) strategy, the application of MIL-101-ED for extracting the antipsychotic drugs and their metabolites in serum samples was developed. The recoveries of antipsychotic drugs and their metabolites in serum ranged from 83.2 to 110.8%, and the related detection limits were all <5.55 ng mL–1. Compared to the traditional extraction methods, the pretreatment steps of MIL-101-ED have the advantages of easy operation and reducing the environmental pollution. Here, we propose that MIL-101-ED, as a kind of restricted access media nanophase material, can be applied to extract antipsychotic drugs in serum samples.

Recovery of water and valuable metals using low pressure nanofiltration and sequential adsorption from acid mine drainage

Acid mine drainage (AMD) contains an array of valuable resources such as Rare Earth Elements (REE) and Copper (Cu) which can be recovered along with fresh water. Low pressure nanofiltration with NF90 membrane was first studied to recover fresh water from synthetic AMD and concentration of dissolved metals for subsequent efficient selective recovery. Organic matter (OM) present in AMD was found to cause membrane fouling which resulted in significant flux decline. Powdered eggshell was investigated as a low-cost adsorbent for OM removal. The study showed that a 0.2 mg/l dose of powdered eggshell adsorbed 100% of OM and Fe with no significant loss of other dissolved metals. A steady permeate flux of 15.5 ± 0.2 L/m 2 h (LMH) was achieved for pre-treated AMD with a solute rejection rate of more than 98%. A chromium-based metal organic framework (MOF) modified with N - (phosphonomethyl) iminodiacetic acid (PMIDA) and an amine-grafted mesoporous silica (SBA15) material was synthesized for selective recovery of REE and Cu, respectively. The two adsorbents were used sequentially to selectively adsorb REE (91%) and Cu (90%) from pH adjusted concentrated feed. The formation of coordinating complexes with carboxylate and phosphonic groups on MOF was found to be the primary driving force for selective REE adsorption. Selective uptake of Cu onto amine-grafted SBA15 was due to the formation of strong chelating bonds between Cu and amine ligands. Both adsorbents remained structurally stable over 5 regeneration cycles. The findings here highlight the practical potential of membrane/adsorption hybrid systems for water and valuable metal (REE) recovery from AMD. • Low pressure NF achieved 80% permeate recovery while concentrating dissolved ions. • Modified MOF and SBA15-NH 2 selectively adsorbed 91% of REE and 90% of Cu. • REE show high affinity to deprotonated phosphonic and carboxyl groups in MOF. • Chelating bonds between Cu and amine groups in SBA15 promotes high selectivity. • High reuse capacity over multiple cycles recorded for both adsorbents.

Preparation and characterization of metal organic framework based composite materials for thermochemical energy storage applications

Using the chromium-based metal organic framework (MIL-101(Cr)) as a host matrix two composite materials were synthesized with Na2S2O3 (10 and 30% w/w) towards thermochemical energy storage (TCES) applications. The prepared composites were characterized using multiple techniques viz. Powder X-ray Diffractometer (PXRD), Dynamic Vapour Sorption (DVS) analyser and Thermogravimetric-Differential Scanning Calorimeter (TG-DSC), etc. The prepared composites were found to exhibit octahedral structures with salt in the pores. The MIL-101(Cr) with 30% Na2S2O3 (w/w) was estimated to yield a high energy storage density (1099.5 J/g) due to its high water vapour adsorption capacity. These composites were subjected to ten continuous adsorption and desorption processes using the DVS analyser to determine their stability for intended applications. The synthesized composites offered good water vapour adsorption capacity, energy storage density, and excellent stability with very little mass variations across the tested cycles. Based on the experimental results, the authors recommend the composite sorbents for TCES applications.

Adsorptive removal of 2,4-dinitrophenol from aqueous phase using amine functionalized metal organic framework (NH2-MIL-101(Cr))

This study reports the successful synthesis of an amine functionalized chromium based metal organic framework ((NH2-MIL-101(Cr)) by hydrothermal method. Characterization of the prepared MOF was carried out by several spectroscopic and analytical techniques in terms of structural, textural, morphological and thermal properties. Notably, a high surface area of 1321 m2/g was obtained for the synthesized NH2-MIL-101(Cr). Furthermore, the MOF showcased remarkable adsorption capacity for the removal of 2,4-dinitrophenol from aqueous medium. Detailed studies for optimizing several process conditions such as pH of 2,4-DNP solution, dosage of adsorbent, initial concentration and temperature were conducted. Results showed that 99% removal of 2,4-DNP was attained with NH2-MIL-101(Cr) at dose‒0.5 g L−1 with pH 4 and initial phenol concentration‒10 mg/L in 50 min. The adsorption mechanism followed pseudo second order kinetic model. The obtained adsorption data was modelled using different isotherm models and best fitting was attained with Langmuir isotherm. The attained high adsorption tendency could be ascribed to the hydrogen bonding interactions between the nitro group of 2,4-DNP and amino group of NH2-MIL-101(Cr).

Cationic graphene-based polymer composite modified with chromium-based metal-organic framework [GP/MIL-53(Cr)] for the degradation of 2,4-dichlorophenol in aqueous solution

Owing to its remarkable water stability, chromium-based metal-organic framework (MIL-53(Cr) has the capacity to remove 2,4-dichlorophenol (2,4-DCP) from aqueous solutions, but the weak adsorptive capacity of the adsorbent limits its utilization. In this work, cationic graphene-based polymer composite (GP) was successfully synthesized with (MIL-53(Cr)) [GP/MIL-53(Cr)] through one-step solvothermal technique and characterized with XRD, SEM, BET, XPS, TEM, and FTIR. Adsorbent dose, pH, initial concentration, and contact time were enhanced to improve the performance of GP/MIL-53(Cr). GP/MIL-53(Cr) displayed a marginal adsorptive performance relative to MIL-53(Cr) and GP. The adsorption of 2,4-DCP mainly depends on the nature of MIL-53(Cr) and the electrostatic attractions of the functional groups on GP surface. Due to the high magnetic properties of GP/MIL-53(Cr), effective solid–liquid separation can be easily achieved. The adsorbate mineralization process stabilizes at 200 min. The pseudo-second-order model adequately fits the adsorption kinetic data, while the Freundlich and Langmuir models gave a good fit with the equilibrium data. The maximum adsorptive capacity of the adsorbents for the adsorbate as calculated from the Langmuir isotherm are 64.9 (GP), 28.2 MIL-53(Cr), and 98.4 mg/g (GP/MIL-53(Cr). The thermodynamic studies revealed that the adsorption process is spontaneous, feasible, and endothermic. Additionally, the excellent performance of GP/MIL-53(Cr) shows that the adsorbent has potential application in treating wastewater.

Chromium-based metal organic framework for pipette tip micro-solid phase extraction: an effective approach for determination of methyl and propyl parabens in wastewater and shampoo samples

BackgroundA chromium-based metal organic framework was synthesized and employed as an efficient sorbent for pipette tip micro-solid phase extraction and preconcentration of parabens from wastewater and shampoo samples up to sub-ppb level before their spectrophotometric analysis.ResultsFactors affecting preconcentration including volume and type of solvent, amount of sorbent, number of extraction, and volume and pH of samples were optimized employing one-variable-at-a-time and response surface methodology. Obtained analytical characteristics of the method proves its usefulness for analysis of real samples. Linear range of the method for parabens was 1.0–200.0 μg/L. Detection limit of the protocol was 0.24 µg/L for propyl paraben and 0.25 µg/L for methyl paraben. Reproducibility of the protocol defined as % RSD was better than 5.78%. Synthesized adsorbent can be re-used for at least 20 extractions.ConclusionThe method showed a good detection limit and precision for determination of methyl- and propyl-paraben in wastewater and shampoo samples.

Palladium nanoparticles supported by functionalized metal-organic framework: an excellent recyclable heterogeneous catalyst for the synthesis of commercially important rose essence, 2-phenyl ethanol

Palladium nanoparticles on ethylenediamine-grafted functionalized chromium-based metal organic framework (Pd-ED-MIL-101) was tested for the hydrogenation of styrene oxide to 2-phenylethanol, the key ingredient of the rose essence. The catalyst was found as an excellent heterogeneous recyclable catalyst for selective hydrogenation of styrene oxide to 2-phenylethanol (100% conversion and ∼100% selectivity) within 2 h in methanol with a catalyst loading only 0.25 mol % palladium at ambient pressure and temperature under molecular hydrogen. If the catalyst loading increases to 0.50 mol % palladium, the conversion time reduces to 1 h. In repeated runs (tested for 5 cycles) showed no loss of activity and selectivity of the catalyst. To the best of our knowledge, the performance of the present catalyst is one of the best compared to all other reported catalysts in terms of conversion, selectivity, reaction time, reaction conditions, purification, catalyst stability, catalyst loading, catalyst recyclability, safety and convenience.

Catalytic hydrogenolysis of alkali lignin in supercritical ethanol over copper monometallic catalyst supported on a chromium-based metal–organic framework for the efficient production of aromatic monomers

The catalytic hydrogenolysis of lignin has been reported as an effective approach for lignin depolymerization owing to its high efficiency for aromatic monomer production. In this study, a series of copper monometallic catalysts over an MIL-101(Cr) support were synthesized and used for the catalytic hydrogenolysis of alkali lignin using supercritical ethanol. First, the optimal copper catalyst for lignin hydrogenolysis was selected. Subsequently, the reaction conditions for catalytic hydrogenolysis were systematically optimized to maximize the total monomer yield. The optimal conditions were determined to be 6 h of reaction time, 20 min of sonication pretreatment, 50% catalyst loading, and 5% lignin loading. Under these conditions, an aromatic monomer yield of 38.5% was obtained; this depolymerized lignin stream, which is mainly composed of G-type monomers, can serve as a promising aromatic feedstock and carbon source for further microbial upgrading and bioconversion to produce various value-added products.

A novel nanohybrid based on metal–organic framework MIL101[formula omitted]Cr/PANI/Ag for the adsorption of cationic methylene blue dye from aqueous solution

In this study, a novel MIL101−Cr/PANI/Ag nanohybrid was synthesized based on a Chromium-based metal-organic framework (MOF) prepared by a hydrothermal method and structurally characterized using various techniques such as FE-SEM, XRD, FT-IR, EDAX, BET, and TEM analyzes. The nanohybrid exhibited active performance due to changes in the UV–Vis absorbencies of the aqueous solutions at λ max=662 nm. MB adsorption over MOF-based composites follows pseudo-second-order kinetics. The influence of various operational parameters such as MIL101−Cr/PANI/Ag mass (20, 30 and 40) 10-4 g, initial dye concentration (15, 25, 35 and 50 mgL−1), pH (2−12) and temperature (25–55∘C) were investigated. The findings showed that size of the MIL101−Cr/PANI/Ag nanohybrid was 153 nm. The total pore volume, BET surface area, and Langmuir surface area were found to be 2861 m2/g, and 1.608 m3g−1, respectively. Zeta potential of MIL101−Cr/PANI and MIL101−Cr/PANI/Ag was equal to −3.8 V and −39.5 V. efficiency was observed for MB adsorption, at the pH = 12, Methylene blue was 25mgL−1, MIL101−Cr/PANI/Ag was 0.03 g and the temperature of 25∘C which led to 96% methylene blue adsorption.

Construction of a Porous Metal-Organic Framework with a High Density of Open Cr Sites for Record N2 /O2 Separation.

The removal of low concentration N2 is of great significance and challenging in the industrial production of high-purity O2 . Herein, a chromium-based metal-organic framework, namely, TYUT-96Cr, is reported, which has an unprecedented N2 capture capacity of 37.46 cm3 cm-3 and N2 /O2 (5:95, v/v) selectivity up to 26.95 (298 K and 1 bar), thus setting new benchmarks for all reported metal-organic frameworks and commercially used ones (Li-LSX and 13X). Breakthrough experiments reveal that N2 can be directly extracted from various N2 /O2 (79:21, 50:50, 5:95, and 1:99, v/v) mixtures by this material, affording a record-high O2 -production scale with 99.99% purity. Density functional theory calculations and in situ infrared spectroscopy studies demonstrate that the high-density open Cr (III) sites in TYUT-96Cr can behave as effective Lewis acidic sites, thus resulting in a strong affinity toward N2 . The high N2 adsorption selectivity, exceptional separation performance, and ultrahigh structural stability render this porous material with great potential for this important industrial application.

Fabrication of chromium based metal organic framework (MIL-101)/activated carbon composites for acetylation of glycerol

Chromium based metal organic framework (MIL-101)/activated carbon composite materials were synthesized using hydrothermal method and the catalytic effect was investigated for the acetylation of glycerol with acetic acid. Activated carbon and chromium based metal organic framework hybrid material was fabricated with two different weight ratio of chromium ion to activated carbon, materials were labelled as AC@MIL-10110, AC@MIL-1015. The characterization of synthesized catalysts was performed using XRD, N2 adsorption, TGA, FTIR, SEM/EDS, XPS, n-butylamine titration, contact angle measurement and TEM in order to explore the relation between the structure and catalytic performance. The effect of addition of the activated carbon on the catalytic activity of materials was determined by considering conversion of glycerol and selectivity of glycerol monoacetate, glycerol 1,3 diacetate and glycerol triacetate. Taguchi orthogonal L9 matrix has been applied to understand the effect of temperature, molar ratio and catalyst loading on the conversion of glycerol and selectivity of acetates. Signal to noise ratio (S/N) and analysis of variance (ANOVA) results revealed that the temperature was the dominant factor affecting the conversion and selectivity. 100% of glycerol was converted to acetates and 5.2% of glycerol triacetate selectivity was achieved at 110 °C, acetic acid/glycerol molar ratio of 9 and catalyst loading of 4 g/L.

Chromium-based metal-organic framework embedded with cobalt phthalocyanine for the sensitively impedimetric cytosensing of colorectal cancer (CT26) cells and cell imaging

In this study, we have prepared the series of nanohybrids of Cr-based metal-organic framework (Cr-MOF) and cobalt phthalocyanine (CoPc) nanoparticles (denoted as Cr-MOF@CoPc) and investigated them as novel platforms of electrochemical cytosensors for determining colorectal cancer (CT26) cells. The developed Cr-MOF@CoPc nanohybrids were composed of irregularly small nanoparticles, mixed metal valence states of Cr2+/Cr3+/Cr5+ and Co2+/Co3+, rich functional groups of C–O and COO and strong fluorescence performance, as well as high specific area and large pore volume. These intrinsic features of Cr-MOF@CoPc nanohybrids endowed them with strong immobilization ability toward aptamer strands via π- π* stacking, electrostatic interaction, and van der Waals force, excellent electrochemical property, strong fluorescence intensity, and good biocompatibility. Compared with cytosensors based on the sole metal MOFs (Cr-MOF and CoPc) and other reported bulk MOF-based sensors, the constructed Cr-MOF@CoPc-based cytosensor exhibited low detection limit toward CT26 cells, for which the sensing performance was modulated by changing the dosage of CoPc nanoparticles. Electrochemical impedance spectroscopy and differential pulse voltammetry results showed extremely low detection limits of 36 and 8 cells mL−1, respectively, within the concentration range of the CT26 cell suspension (50–1 × 107 cells mL−1), along with high selectivity, excellent stability, and acceptable reproducibility. Thus, the prepared cytosensor can be extensively applied for the analysis of other kinds of cancer cells when anchored their corresponding aptamer strands, providing great potential applications in the biosensor and biomedical fields.

PEI-modified chromium-based metal organic framework for Cr(VI) removal from aqueous solution

PEI-modified chromium-based metal organic framework for Cr(VI) removal from aqueous solution

Preparation and performance of functionalized metal organic framework, MIL-101, for Knoevenagel reaction

In this study, the effect of surface basicity on the structure and catalytic activity of chromium based metal organic framework, MIL-101, was investigated. Increase in surface basicity was achieved by functionalization using four different deep eutectic solvents (DESs) and ethylene diamine for comparison. Also the superior properties of DES for functionalization was highlighted. The characterization of samples was performed using BET, XRD, FTIR, SEM, TGA techniques and zeta potential measurements. The catalytic activity of raw MIL-101 and functionalized MIL-101 samples were tested in Knoevenagel reaction performing between malononitrile and benzaldehyde. The maximum conversion values were achieved as 98.3, 99.5 and 100% for MIL-101, MIL-101-ED and MIL-101-D1, respectively when the reaction conditions were 1:1 reactant molar ratio, 5 ​wt% of catalyst loading and at 70 ​°C. Besides achieving a high conversion, DES was found to be advantageous as grafting agent due to its having low volatility, high biodegradability and environmental friendly nature when compared to the harmful and toxic solvents.