Metal Organic Framework MIL-101 Research Articles

Nghiên cứu ảnh hưởng của công suất siêu âm đến đặc trưng tính chất của vật liệu khung cơ kim MIL-100

The metal-organic framework MIL-100 (Fe) was successfully synthesized using the ultrasonic method under different ultrasonic power. The as-synthesized materials were characterized by XRD, SEM, FT-IR and BET. The results showed that these materials have dimensions of a size range of 200-300 nm with similar morphology and structure. Among all the ultrasonic power studied, the material synthesized at ultrasonic power of 1080 W has the largest surface area of 1080.11 m2/g and reaction efficiency of 72.09%.

Magnetic solid-phase extraction of tetracyclines from milk using metal-organic framework MIL-101(Cr)-NH2 functionalised hydrophilic magnetic nanoparticles

Novel metal-organic framework MIL-101(Cr)-NH2 functionalised hydrophilic polydopamine-modified Fe3O4 magnetic nanoparticles (Fe3O4@PDA@MIL-101(Cr)-NH2) were synthesised and used as magnetic solid-phase extraction (MSPE) adsorbents for extracting tetracyclines (TCs) from milk samples. The integrated Fe3O4@PDA@MIL-101(Cr)-NH2 exhibited convenient magnetic separation and exceptional multi-target binding capabilities. Furthermore, the PDA coating significantly enhanced the hydrophilicity and extraction efficiency of the material, thereby facilitating the extraction of trace TCs. Various factors affecting MSPE, such as adsorbent dosage, extraction time, pH value, and desorption conditions, were optimised. The developed MSPE method coupled with high-performance liquid chromatography demonstrated good linearity (R2 ≥ 0.9989), acceptable accuracy (82.2%–106.1%), good repeatability (intra-day precision of 0.8%–4.7% and inter-day precision of 1.1%–4.5%), low limits of detection (2.18–6.25 μg L−1), and low limits of quantification (6.54–18.75 μg L−1) in TCs detection. The approach was successfully used for the quantification of trace TCs in real milk samples.

Sustainable metal-organic framework based paper sheet as wallpaper for passive indoor moisture control

Passive indoor moisture control is a meaningful way to reduce HVAC operation and improve building energy efficiency. Metal-organic frameworks (MOFs) have been considered one of the most promising sorbent materials for passive indoor moisture control. However, the powder form of MOF is challenging to use in the built environment. Typical shaping methods like pellets, beads, and coating can lead to problems like partial pore blocking, insufficient mechanical stability, amorphization, and low material utilization. Here, we report a new sustainable MOF paper sheet comprising 25% cellulosic fibers and 75% MOF MIL-100(Fe) powder. The porous polymer matrix provides good support and fixation for MOF particles, so it’s more applicable in the built environment. The crystalline and pore structure characteristics of the MOF in the membrane are well preserved. Hydro characteristic test results show that MIL-100(Fe) paper sheet has high water vapor uptake, S-shape isotherm, mild regeneration condition, and high MBV. Then, a numerical model was developed to calculate the relation between a material’s MBV and its thickness. MIL-100(Fe) paper sheet with the most efficient thickness was applied as wallpaper in a building energy simulation model. The simulation result shows that the MIL-100(Fe) paper sheet is promising for passive indoor moisture control. It can remove about 45%-55% of the latent cooling load in most European climate types.

MOF-derived α-Fe2O3@Fe3O4 on carbon fiber fabric for lithium-ion anode applications

Owing to the current development in emerging fields as electric motoring, biomedical sensors or new generation of mobile phones, new functionalities are required for the new generation of Li-ion batteries as flexibility or structurality. Thus, Metal-Organic Framework (MOF)-derived α-Fe2O3@Fe3O4 coating on carbon fiber fabric has been developed in this study for Lithium-ion battery anode purposes. MOF-derived synthesis is a well-known strategy to obtain Transition Metal Oxides (TMOs) which better electrochemical performance than bare TMOs. On the other hand, synthesis on carbon fiber fabric allows to develop new electrodes for multifunctional energy storage devices in which the coating provides high specific capacity, while the carbon fiber substrate provides stiffness but high flexibility, mechanical strength, and electrical conductivity. This TMO coating was achieved by a novel MOF MIL-100 direct synthesis on carbon fiber and subsequent calcination, the effects of calcination on the composition, texture and morphology of the coating, as well as its electrochemical performance, were studied. As the best result, calcinated samples during 2 h showed the optimal synergic effects between the coating and carbon fiber, exhibiting a specific capacity of 328.6 mAh/g at 25 mA/g, an excellent rate capability and a capacity retention of 89.7 % after 100 galvanostatic charge-discharge cycles. Nevertheless, it is important to note that the novelty of this work is not only based on the electrochemical performance but also on the novel synthesis of MIL-100 directly over the carbon fibers. This novel synthesis opens the way to new variety of TMO coatings for electrodes of all-solid-state energy storage devices.

Enhancing the photoelectric performance of TiO2-based heterojunction using the hydrothermal decomposition of MIL-125 strategy for sensitive detection of Bisphenol A

Due to its outstanding conductive properties, TiO2-based heterojunctions have extensive applications in the field of photoelectrochemical sensors. However, due to surface energy and van der Waals forces, TiO2 tends to aggregate and presents an uneven distribution, which reduces the overall performance of these heterostructures. To overcome these challenges and achieve a uniform distribution of TiO2 within the heterojunction, the characteristic of gradual decomposition of the metal-organic framework MIL-125 under hydrothermal conditions was employed. This process gradually generates TiO2 particles that slowly participate in the construction of the heterojunction. By combining the exceptional light absorption properties and appropriate bandgap widths of CdS and CdIn2S4, a uniformly distributed flower-globular ternary heterojunction CdS/CdIn2S4/TiO2-FG was successfully synthesized. In comparison to the disordered heterojunction CdS/CdIn2S4/TiO2-DO, CdS/CdIn2S4/TiO2-FG exhibits enhanced visible light absorption properties and photoelectric conversion efficiency. Taking Bisphenol A (BPA) as a model, a signal-off photoelectrochemical (PEC) aptasensor based on the CdS/CdIn2S4/TiO2-FG was established and exhibited a high sensitive detection for BPA with a linear response range from 10−1 to 107 pM, as well as an ultralow detection limit of 0.015 pM, revealing vivid selectivity, stability, and reproducibility. Therefore, this study offers an efficient and straightforward approach for the preparation of TiO2-based heterojunctions with superior photoelectric activity.

Probing the sites on metal oxide cluster nodes of metal organic framework MIL-96, MIL-100 and MIL-110

Metal oxide cluster MOF nodes are a good platform to understand the reactivities and catalysis. MIL-96, MIL-100 and MIL-110 are drastically different in their node structures. Following our previous reported results for MIL-100, we report the modified synthesis and characterization of the node sites of MIL-110 and MIL-96 and their catalytic sites by using methanol dehydration as probe reaction. We show that these MOFs can be synthesized from the same solution by adding various amounts of formic acid as modulator. Herein, the chemistry of hydroxyl, formate and methoxy groups were used to probe the three MOFs’ node sites. IR data show the bonding structures of these ligands are highly diverse, with reactivities and flexibilities depending on node sites. We identified terminal OH group and various µ2-OH groups in single, paired or hydrogen bonded modes on the MOF nodes. Formate ligands were introduced to the node sites during the synthesis or by a post treatment in formic acid/DMF solution. Surprisingly, the bonding modes of formate ligands on Al3(OH)3 node structure of MIL-96 can be reversibly switched between monodentate and bidentate through a process induced by water molecules. Further, methoxy ligands—likely to be the intermediate for catalytic reaction—were also observed on the node sites under methanol dehydration conditions at 250 ℃. The activities of MIL-100 and MIL-96 for methanol dehydration determined by TOF per node were similar, both approximately 3-fold higher than that of MIL-110. The data suggests that catalytic sites incorporate adjacent vacancy and defect node sites, which constitute a minority among all observed MOF node sites. We foresee the opportunities in expanding the chemistry and understanding into other MOFs with metal oxide cluster nodes.

Enhanced photocatalysis using metal-organic framework MIL-101(Fe) for crude oil degradation in oil-polluted water

Enhanced photocatalysis using metal-organic framework MIL-101(Fe) for crude oil degradation in oil-polluted water

Oxaliplatin-Loaded Mil-100(Fe) for Chemotherapy-Ferroptosis Combined Therapy for Gastric Cancer.

Oxaliplatin (Oxa) is a commonly used chemotherapy drug in the treatment of gastric cancer, but its toxic side effects and drug resistance after long-term use have seriously limited its efficacy. Loading chemotherapy drugs with nanomaterials and delivering them to the tumor site are common ways to overcome the above problems. However, nanomaterials as carriers do not have therapeutic functions on their own, and the effect of single chemotherapy is relatively limited, so there is still room for progress in related research. Herein, we construct Oxa@Mil-100(Fe) nanocomposites by loading Oxa with a metal-organic framework (MOF) Mil-100(Fe) with high biocompatibility and a large specific surface area. The pore structure of Mil-100(Fe) is conducive to a large amount of Oxa loading with a drug-loading rate of up to 27.2%. Oxa@Mil-100(Fe) is responsive to the tumor microenvironment (TME) and can release Oxa and Fe3+ under external stimulation. On the one hand, Oxa can inhibit the synthesis of DNA and induce the apoptosis of gastric cancer cells. On the other hand, Fe3+ can clear overexpressed glutathione (GSH) in TME and be reduced to Fe2+, inhibiting the activity of glutathione peroxidase 4 (GPX4), leading to the accumulation of intracellular lipid peroxides (LPO), and at the same time releasing a large number of reactive oxygen species (ROS) through the Fenton reaction, inducing ferroptosis in gastric cancer cells. With the combination of apoptosis and ferroptosis, Oxa@Mil-100(Fe) shows a good therapeutic effect, and the killing effect on gastric cancer cells is obvious. In a nude mouse model of subcutaneous tumor transplantation, Oxa@Mil-100(Fe) shows a significant inhibitory effect on tumor growth, with an inhibition rate of nearly 60%. In addition to its excellent antitumor activity, Oxa@Mil-100(Fe) has no obvious toxic or side effects. This study provides a new idea and method for the combined treatment of gastric cancer.

Roles of varying carbon chains and functional groups of legacy and emerging per-/polyfluoroalkyl substances in adsorption on metal-organic framework: Insights into mechanism and adsorption prediction

Metal-organic frameworks (MOFs) are promising adsorbents for legacy per-/polyfluoroalkyl substances (PFASs), but they are being replaced by emerging PFASs. The effects of varying carbon chains and functional groups of emerging PFASs on their adsorption behavior on MOFs require attention. This study systematically revealed the structure-adsorption relationships and interaction mechanisms of legacy and emerging PFASs on a typical MOF MIL-101(Cr). It also presented an approach reflecting the average electronegativity of PFAS moieties for adsorption prediction. We demonstrated that short-chain or sulfonate PFASs showed higher adsorption capacities (μmol/g) on MIL-101(Cr) than their long-chain or carboxylate counterparts, respectively. Compared with linear PFASs, their branched isomers were found to exhibit a higher adsorption potential on MIL-101(Cr). In addition, the introduction of ether bond into PFAS molecule (e.g., hexafluoropropylene oxide dimeric acid, GenX) increased the adsorption capacity, while the replacement of CF2 moieties in PFAS molecule with CH2 moieties (e.g., 6:2 fluorotelomer sulfonate, 6:2 FTS) caused a decrease in adsorption. Divalent ions (such as Ca2+ and SO42−) and solution pH have a greater effect on the adsorption of PFASs containing ether bonds or more CF2 moieties. PFAS adsorption on MIL-101(Cr) was governed by electrostatic interaction, complexation, hydrogen bonding, π-CF interaction, and π-anion interaction as well as steric effects, which were associated with the molecular electronegativity and chain length of each PFAS. The average electronegativity of individual moieties (named Me) for each PFAS was estimated and found to show a significantly positive correlation with the corresponding adsorption capacity on MIL-101(Cr). The removal rates of major PFASs in contaminated groundwater by MIL-101(Cr) were also correlated with the corresponding Me values. These findings will assist with the adsorption prediction for a wide range of PFASs and contribute to tailoring efficient MOF materials.

Linker-Preserved Iron Metal-Organic Framework-Based Lateral Flow Assay for Sensitive Transglutaminase 2 Detection in Urine Through Machine Learning-Assisted Colorimetric Analysis.

A groundbreaking demonstration of the utilization of the metal-organic framework MIL-101(Fe) as an exceptionally perceptive visual label in colorimetric lateral flow assays (LFA) is described. This pioneering approach enables the precise identification of transglutaminase 2 (TGM2), a recognized biomarker for chronic kidney disease (CKD), in urine specimens, which offers a remarkably sensitive naked-eye detection mechanism. The surface of MIL-101(Fe) was modified with oxalyl chloride, adipoyl chloride, and poly(acrylic) acid (PAA); these not only improved the labeling material stability in a complex matrix but also achieved a systematic control in the detection limit of the TGM2 concentration using our LFA platform. The advanced LFA with the MIL-101(Fe)-PAA label can detect TGM2 concentrations down to 0.012, 0.009, and 0.010 nM in Tris-HCl buffer, urine, and desalted urine, respectively, which are approximately 55-fold lower than those for a conventional AuNP-based LFAs. Aside from rapid TGM2 detection (i.e., within 20 min), the performance of the MIL-101(Fe)-PAA-based LFA on reproducibility [coefficients of variation (CV) < 2.9%] and recovery (95.9-103.2%) along with storage stability within 25 days of observation (CV < 6.0%) shows an acceptable parameter range for quantitative analysis. A sophisticated sensing method grounded in machine learning principles was also developed, specifically aimed at precisely deducing the TGM2 concentration by analyzing immunoreaction sites. More importantly, our developed LFA offers potential for clinical measurement of TGM2 concentration in normal human urine and CKD patients' samples.

Optimal adsorption of pefloxacin antibiotics from aqueous solutions: Improved performance with metal-organic framework MIL-101(Cr)

The widespread use and subsequent release of antibiotics by humans and animals pose health and environmental risks, compelling their removal from aquatic ecosystems. MIL-101(Cr), a metal-organic framework (MOF), exhibits versatile applications in antibiotic adsorption owing to its exceptional structural characteristics. In this context, MIL-101(Cr) nanoparticles are successfully prepared via the hydrothermal method to remove pefloxacin (PEF) from aqueous solutions. The resulting MIL-101(Cr) adsorbents showcase high crystallinity (97.6%), a large surface area (3166 m2/g), broad nanopore sizes, good thermal stability, and efficient reusability. Factors including initial PEF concentration, pH, dosage of adsorbent, and temperature are thoroughly investigated. The findings reveal a good adsorption capacity (254.3 mg/g) with an optimal removal efficiency (99.7%) at 308 K in a neutral pH of 7.0 when the adsorbent dosage is 250 mg/L and the initial PEF concentration is 200 mg/L within 80 min of contact. Among the three adsorption isotherms (Langmuir, Freundlich, Temkin models), the Langmuir equation best fits the studies, indicating a maximum adsorption capacity of 253.8 mg/g at 25°C, while the experimental equilibrium adsorption capacity is 229.2 mg/g at the same temperature. Adsorption kinetics aligns with the pseudo-second-order model. Thermodynamic parameters and activation energy affirm the endothermic and spontaneous behavior of the adsorption process, attributed to both physisorption and chemisorption. This study highlights the promising potential of synthesized MOF nanocrystals as an effective adsorbent for antibiotics in wastewater treatment and environmental remediation.

Shaping of MIL-53-Al and MIL-101 MOF for CO2/CH4, CO2/N2 and CH4/N2 separation

Metal-organic frameworks (MOF) are promising materials for gas storage and separation. The formulation and shaping of MOFs in mechanically stable bead forms is an essential requirement for their practical application as an adsorbent for gas and liquid mixture separations. In this work, MIL-53-Al and MIL-101 MOF beads are synthesized using sodium alginate as a binder, and calcium chloride as a gelling agent. The synthesized MIL-53-Al and MIL-101 MOF beads are characterized by powder X-ray diffraction (PXRD), BET surface area, porosity analysis from N2 uptake data at 77 K, FTIR, TGA, and scanning electron microscopy (SEM). The isothermal equilibrium adsorption uptake of CH4 and N2 gases is measured up to 10 bar pressure while the CO2 equilibrium uptake is measured up to 1 bar at 298 and 313 K respectively. The isotherm data of all adsorbates are fitted in Dual Site Langmuir (DSL) isotherm equations. The adsorption selectivity for CH4/N2, CO2/CH4, and CO2/N2 binary systems are predicted using the Ideal Adsorbed Solution Theory (IAST) method. The dynamic column breakthrough experiments are carried out on MIL-53-Al beads for CH4/N2 (30:70 and 50:50 v/v), CO2/CH4 (45:55 v/v) and CO2/N2 (15: 85 v/v) feed mixtures. The IAST selectivity and breakthrough time obtained under the same superficial velocity, pressure, and temperature conditions follow the order CO2/N2 > CO2 /CH4 > CH4/N2. The MIL-53-Al beads show higher CH4/N2, CO2/CH4, and CO2/N2 selectivity for the targeted mixtures than MIL-101 beads.

Metal-organic framework MIL-101(Cr): An efficient catalyst for the synthesis of dihydro-pyrimidinones

In this work, a metal–organic framework, MIL-101(Cr), was synthesized using hydrothermal method. As synthesized MIL-101(Cr) was characterized using various techniques such as X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDAX), Raman spectroscopy, and Brunauer-Emmett-Telller (BET) surface area analysis. Dihydro-pyrimidinone derivatives were synthesized in the absence of solvent over the MIL-101(Cr) catalyst. These dihydro-pyrimidinone derivatives were characterized by FTIR, 1H and 13C nuclear magnetic resonance spectroscopy. Less hazardous reactants, milder reaction conditions, and relatively simple catalysts to synthesize dihydro-pyrimidinones are the added advantages of our protocol. Optimal yield, swift reaction time, and the retention of a good catalytic activity up to five cycles are the special benefits of our protocol.

Metal–organic framework MIL-101(Cr): an efficient catalyst for the synthesis of biphenyls and biphenyl diols

Metal–organic framework MIL-101(Cr): an efficient catalyst for the synthesis of biphenyls and biphenyl diols

Copper-based catalysts supported on novel Metal-Organic Framework MIL-125(Ti) for selective catalytic reduction of NO with CO

A type of novel copper-based catalysts supported on MIL-125(Ti), a kind of metal–organic frameworks (MOFs), noted as Cu-MIL-125(Ti), was synthesized for the selective catalytic reduction (SCR) of NO with CO. The reactivity of Cu-MIL-125 catalysts for selective catalytic reduction of NO by CO (SCR-CO) was evaluated in a fixed bed reactor. A number of characterization techniques were used to explore the basic physical–chemical properties and the reaction mechanism. The results showed that the large specific surface area and micro-mesopores of the MIL-125 carrier promoted the high dispersion of Cu species, leading to the outstanding SCR-CO performance. Among the results, 90 % NO conversion and 92 % N2 selectivity were proved for the 6.2Cu-MIL-125 catalyst at 325 °C in oxygen-rich environment. XRD results showed that the metal organic frame structure and TiO2 structure coexisted in the catalysts, which was the major factor to influence the NO reduction efficiency. XPS characterization and H2-TPR reduction results showed that the catalytic performance of the catalyst was mainly determined by the path of Cu2+ reduction to Cu+ and then Cu+ to Cu0. Lewis acid on the catalyst surface played an important role in the CO-SCR reaction. In situ DRIFTS study proved that NO was first adsorbed on the surface of the catalyst to form different nitrate, NCO and isocyanate species. Then the adsorbed NO and the intermediates reacted with gaseous CO, which is a typical interaction between adsorbed molecules and gas molecules. Oxygen vacancies on the catalyst surface was involved in the reaction of CO to CO2. The whole reaction follows the M–K mechanism and the E-R mechanism. A preliminary reaction pathway was proposed based on the in situ DRIFTS results.

Effect of chitosan coating on drug carrier capacity of metal organic framework MIL-100(Fe) contained cyclophosphamide.

In recent years, the field of biomedical engineering, particularly drug delivery, has seen significant advancements in the evaluation of various drug carriers. Metal-organic frameworks (MOFs), are porous materials with strong coordination bonds. They have emerged as a promising tool for enhancing the effectiveness of drug delivery. In this investigation, the effect of chitosan coating on cyclophosphamide loading of MIL-100(Fe) was studied in computational and experimental way. The chitosan-coated MIL-100(Fe) containing cyclophosphamide (MIL-100(Fe)/CS/CP) was characterized by SEM, FTIR, BET, DLS, and powder X-ray diffraction analysis. The drug loading and release process were quantified using UV-spectroscopy. In vivo-In vitro study was performed. The result of drug loading in chitosan-coated MIL-100(Fe) with a drug payload of 32% revealed a significant increase compared with the MIL-100(Fe) with a 26.41% payload. According to the DLS analysis the existence of chitosan increase MIL-100(Fe) particle size (381 to 463nm) and change the zeta potential from 18 to -17mV. The toxic effect of MIL-100(Fe)/CS/CP was determined on human breast cancer (MCF-7) cells. In vivo images and H&amp;E analysis shows inhibition properties of MIL-100(Fe)/CS/CP on tumor cells. The amount of drug loading of MIL-100(Fe) particles and MIL-100(Fe)/CS was simulated using molecular dynamic software LAAMPS. MIL-100(Fe) was synthesized biofriendly at room pressure and temperature with an Iron (II) chloride source coated with chitosan (CS) a natural polysaccharide. Incorporating MIL-100(Fe) with this natural polymer enhanced the drug loading capacity of MIL-100(Fe) and controlled drug release.

Molecular Dynamics Simulation of the Adsorption and Diffusion of C8 Aromatic Isomers in MIL-47(V).

The separation of C8 aromatic isomers (oX: o-xylene, pX: p-xylene, mX: m-xylene, and EB: ethylbenzene) remains an enormous challenge in industrial production due to their similar molecular structures and physical properties. Porous materials with suitable pore structures and selective recognition sites to discriminate the slight structural differences of isomers are imminently needed. In this paper, MIL-47(V) with a three-dimensional (3D) grid structure of 10.5 × 10.5 Å2 and a one-dimensional (1D) diamond channel was selected as the adsorbent. However, the mechanism of the adsorption and separation of C8 aromatic isomers in porous materials still needs to be understood. Given the importance of C8 aromatic isomers' confinement in MIL-47(V) for adsorption and diffusion applications, it is important to understand C8 aromatic isomers' behavior in MIL-47(V). Here, we demonstrated from a simulation perspective that metal-organic frameworks MIL-47(V) with one-dimensional (1D) diamond channels can identify C8 aromatic isomers. Molecular dynamics (MD) simulations have shown that organic ligands with guest response sites of MIL-47(V) can effectively distinguish between C8 aromatic isomers by adaptation to the shape of a specific isomer. MIL-47(V) has high adsorption and an excellent separation sequence between C8 aromatic isomers: oX > pX ≈ mX > EB. Significant differences exist in π-π superposition interactions between C8 aromatic isomers and between C8 aromatic isomers and the skeletons. This phenomenon is mainly caused by the unique pore structure and guest response characteristics of MIL-47(V). This work is identified as a supplementary instruction to experimental research and is expected to provide profound insights into research on developing C8 aromatic isomers' adsorption and separation and theoretical support.

A flower-like heterojunction for highly photocatalytic treating oxytetracycline based on chrome-based metal-organic frameworks decorated BiOCl nanosheet

The widespread use of antibiotics poses significant risks to both human health and the environment. Among various approaches, photocatalysis has emerged as a promising method for addressing the issue of antibiotic residues. BiOCl, a semiconductor photocatalyst, has attracted attention due to its distinctive structure. However, the limited light utilization efficiency of its ultraviolet light responsiveness remains a challenge. In this study, we developed a heterojunction by decorating BiOCl with metal-organic frameworks (MOFs) MIL-100(Cr), referred to MIL-100(Cr)/BiOCl (MB), to efficiently treat the antibiotic oxytetracycline (OTC) under visible light irradiation. Various analytical techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy, were used to verify the formation of the MB heterojunction. The interaction between MIL-100(Cr) and BiOCl in the MB heterojunction substantially enhances the responsiveness to visible light, increases the specific surface area, facilitates the separation and transfer of charged carriers, and ultimately results in a significant enhancement in visible light-driven photocatalytic performance for OTC degradation. This study explores the application of narrow/wide band gap nanomaterials-based nanocomposites in environmental remediation by constructing heterojunctions.

Insight into the purification of arsenic-contaminated acid water by metal–organic framework MIL-53(Fe) with sulfite: The generation and effect of Fe(IV)

Iron based metal–organic frameworks (Fe-MOFs) have garnered international interest as a novel and promising category of adsorbent materials for the elimination of arsenic from neutral waters. Nevertheless, their practical implementation is constrained by their inadequate adsorption capacity for aqueous arsenite (As(III)), a prevalent arsenic species found in acidic environments such as acid mine drainage. Herein, a novel oxidation-adsorption process to effectively purify As(III)-contaminated water is constructed by combining the MIL-53(Fe) of high acid resistance with sulfite (S(IV)). Notably, the adsorption capacity of the MIL-53(Fe)/S(IV) process for As(III) at pH 3.5 reached 86.4 mg g−1, surpassing the values achieved by MIL-53(Fe) alone by 21.6 times for As(III) and 1.62 times for As(V) (oxidized As(III)). During the oxidation process, MIL-53(Fe) effectively activated S(IV), leading to the formation of the crucial intermediate SO5•−, which then underwent two distinct pathways to respectively generate Fe(IV) and SO4•−, accounting for rapid oxidation of As(III). In the adsorption process, the S(IV) activation (i.e., complexation and electron transfer) on the MIL-53(Fe) surface created additional adsorption sites by dredging the pores and altering the electron cloud distribution within the adsorbent. Furthermore, As(V) trended to form monodentate complexes with surface Fe (e.g., FeOAs bond) in the MIL-53(Fe)/S(IV) process. Notably, this oxidative removal process demonstrated reliable performance in complex water matrices and practical arsenic-contaminated waters. Overall, this study presents a promising strategy to enhance the efficacy of Fe-MOFs for the removal of As(III).

Fluorescent aptasensor mediated with multiple ssDNA for sensitive detection of acetamiprid in vegetables based on magnetic Fe3O4/C-assisted separation.

Acetamiprid (ACE) is a highly effective broad-spectrum insecticide, and its widespread use is potentially harmful to human health and environmental safety. In this study, magnetic Fe3O4/carbon (Fe3O4/C), a derivative of metal-organic framework MIL-101 (Fe), was synthesized by a two-step calcination method. And a fluorescent sensing strategy was developed for the efficient and sensitive detection of ACE using Fe3O4/C and multiple complementary single-stranded DNA (ssDNA). By using aptamer with multiple complementary ssDNA, the immunity of interference of the aptasensor was improved, and the aptasensor showed high selectivity and sensitivity. When ACE was present, the aptamer (Apt) combined with ACE. The complementary strand of Apt (Cs1) combined with two short complementary strands of Cs1, fluorophore 6-carboxyfluorescein-labeled complementary strand (Cs2-FAM) and the other strand Cs3. The three strands formed a double-stranded structure, and fluorescence would not be quenched by Fe3O4/C. In the absence of ACE, Cs2-FAM would be in a single-chain state and would be adsorbed by Fe3O4/C, and the fluorescence of FAM would be quenched by Fe3O4/C via photoelectron transfer. This aptasensor sensitively detected ACE over a linear concentration range of 10-1000nM with a limit of detection of 3.41nM. The recoveries of ACE spiked in cabbage and celery samples ranged from 89.49% to 110.76% with high accuracy.