Search Results (114)

This study employs molecular dynamics simulations to investigate the influence of functionalized UiO-66 materials (with -H, -NH₂, -NO₂, and -(OH)₂ groups) on the adsorption and diffusion behaviors of ethanol and waste oil before transesterification reactions. A multi-scale modeling approach, including a three-layer interfacial model, surface adsorption, and intra-framework adsorption, was utilized to systematically evaluate the effects of functionalization on structural properties, molecular diffusion, adsorption performance, and interfacial interactions. The simulation results reveal that functionalization enhances the intrinsic diffusivity of the metal–organic framework but generally suppresses the diffusion of ethanol and waste oil. The -(OH)₂ group exhibits the most significant diffusion hindrance due to steric effects and strong hydrogen bonding. Adsorption of waste oil is dominated by coordination and hydrophobic interactions, while ethanol adsorption relies on hydrogen bonding. Within the framework, functionalization does not improve ethanol adsorption capacity; instead, pristine UiO-66 shows the highest uptake due to its optimal pore size. Adsorption energy calculations on the (002) surface indicate that the -NO₂ group exhibits the strongest affinity for oleic acid, owing to its strong electronegativity and synergistic effects with metal sites. For polyunsaturated fatty acids, adsorption performance depends critically on the compatibility between the hydrophobic pore environment and molecular conformation. Ethanol adsorption is governed primarily by hydrogen bonding and metal coordination. This study provides molecular-level insights into the structure–function relationships governing pre-reaction adsorption and mass transport mechanisms of functionalized UiO-66 in transesterification reactions, providing a theoretical foundation for the rational design of efficient pre-reaction microenvironments in biodiesel catalysts. Full article

Arsenic contamination, mainly in the arsenate (As(V)) form, continues to pose a serious threat to groundwater quality worldwide due to its long-term stability and toxicity at very low levels. Herein, we demonstrate, for the first time, a three-dimensional graphene oxide-based nanocomposite composed of Cu nanoparticle-doped, amino-functionalized UiO-66 (Cu/UiO-66-NH₂) anchored on a graphene oxide framework (Cu/UiO-66-NH₂@GO) as a novel and efficient nanosorbent for the rapid removal of As(V) in groundwater-like solutions. The nanocomposite was characterized by SEM and HRTEM to confirm the hybrid structure and by XRD, N₂ adsorption–desorption isotherms, and XPS to investigate crystallinity, porosity, and surface chemistry. The derived material exhibited a highly dispersed morphology and performed rapid arsenate solid-phase extraction to attain equilibration within 10 min and was effective for a wide pH range of 2–11. The best fit for the kinetic profiles was provided by the pseudo-second-order model. Interestingly, the maximum adsorption capacity of 747.9 mg g⁻¹ at pH 6.8 was achieved, demonstrating the benefits of the complementary pairing of dispersive GO sheets and Zr-MOF adsorption domains with Cu-derived active sites. Mechanistically, the enhanced uptake is ascribed to a combination of effects, including electrostatic pre-concentration, ligand exchange, and inner-sphere complexation at metal-oxo nodes; spectroscopic analysis (XPS and FTIR) suggests that the majority of arsenate is immobilized via a strong Zr-O-As bond at coordinatively unsaturated Zr centers, which is in line with t-ZrO₂-like surface domains formed within the nanocomposite. The embedded GO support inhibits further framework interpenetration and enhances active site availability and mass transport, leading to fast and high-capacity arsenate capture in groundwater samples with related conditions. Taken together, this work presents a powerful design concept that integrates unique GO-supported, Cu-modified UiO-66-NH₂ with Zr-O binding motifs to afford high-rate remediation nanocomposites, providing an excellent platform for next-generation arsenate remediation materials. Full article

Detection of formaldehyde is of great significance for environmental monitoring and public health. Although amino-modified MOF nanomaterials have been widely adopted to improve the gas-sensing properties for hazardous gases, the fundamental enhancement mechanism is still insufficiently clarified, especially for formaldehyde-sensing material. In this work, the adsorption enthalpies of formaldehyde on UiO-66 and UiO-66-NH₂ were quantitatively extracted via MEMS variable-temperature adsorption experiments, yielding values of −21.8 and −45.9 kJ/mol, respectively. The results demonstrate that amino-modified UiO-66-NH₂ enables reversible adsorption between physisorption and chemisorption, which is more favorable for gas-sensing applications. Furthermore, a formaldehyde sensor was fabricated based on a MEMS resonant microcantilever. Gas-sensing performance tests indicate that the UiO-66-NH₂-based sensor displays a remarkable response to 0.5–10 ppm formaldehyde with a detection limit of 17 ppb and high selectivity. The significantly improved sensing performance experimentally validates the reasonability of the proposed mechanism. This work provides a reliable strategy for revealing the sensitivity enhancement mechanism and developing high-performance MOF-based formaldehyde sensors. Full article

Metal–organic frameworks (MOFs) are unique microporous materials being explored for a wide range of applications. Their porosity and high surface areas can readily be exploited for guest–host interactions, separations, and photochemical catalysis, but many suffer from poor charge separation and fast electron–hole recombination. Introducing structural defects, such as missing linkers or metal nodes, can create unsaturated metal sites and alter band structure, conductivity, and light absorption, improving photocatalytic performance. UiO-66-NH₂ and MIL-125-NH₂ are water-stable, visible-light-absorbing MOFs well suited for photocatalytic degradation of organic dyes. In this work, the influence of defect engineering on photocatalytic properties of MOFs was investigated using formic and acetic acid modulators with UiO-66-NH₂ and variable temperature with MIL-125-NH₂ during synthesis. The resulting materials were characterized by XRD, FTIR and SEM/EDS. Defect states were tracked using N₂ adsorption/BET analysis and UV–Vis spectroscopy. Photocatalytic activity was evaluated by monitoring Rhodamine B (RhB) degradation in aqueous solution under simulated solar irradiation. It was found that increased temperature beyond 120 °C during synthesis promotes mesopore formation and decreases the bandgap in MIL-125-NH₂, resulting in a more photoactive material. Defective MIL-125-NH₂ synthesized at 150 °C showed the most defects and proved to be the best photocatalyst investigated in this study. Formic acid modulation in UiO-66-NH₂ generated smaller crystallites that slightly increased the bandgap; however, the surface area decreased proportionally with the amount of formic acid used. The decreased surface area and observed enhancement in photocatalytic degradation of RhB suggest that formic acid introduces defects into the UiO-66-NH₂ framework that enhance photocatalytic properties. UiO-66-NH₂ treated with acetic acid resulted in larger crystals, increased bandgaps, and increased surface areas, suggesting that acetic acid simply modulates growth rather than imparting defects to the framework. Full article

CO₂ cycloaddition with epoxides offers a sustainable route for CO₂ utilization, yet the simultaneous activation of both substrates remains challenging. Herein, using UiO-66(Zr)-NH₂ (denoted as UZN) as a model system, we illustrate that dual-active sites consisting of unsaturated Zr⁴⁺ centers and amine groups can efficiently accelerate CO₂ fixation with epoxides under visible light. The unique ensemble in UZN optimizes light harvesting, promotes charge carrier separation, and enriches bifunctional active sites for efficient adsorption and activation of epoxides and CO₂. Consequently, UZN exhibits significantly improved CO₂-epoxide cycloaddition performance compared to UiO-66(Zr)-H (denoted as UZH), achieving a PC yield of 99.5%, with a production rate of 9.97 mmol·g⁻¹·h⁻¹. This work establishes a clear coordination–photocatalytic synergy in MOF-based systems and provides fundamental insights and a generalizable strategy for designing advanced catalysts for CO₂ transformation. Full article

Emerging pharmaceutical pollutants such as acetaminophen (ACE) pose health and environmental risks. Solar photocatalysis provides a sustainable and efficient treatment option. In this study, UiO-66-NH₂ metal–organic framework was immobilized on cotton fabrics to enable their application in both batch and continuous flow systems. Cotton, a biodegradable and low-cost support, was first functionalized by two strategies: hydroxylation (-OH) and carboxylation (-COOH), to promote MOF anchoring. Cotton fabric functionalization and MOF growth were confirmed by ATR and X-ray diffraction, while SEM and EDX analyses revealed that carboxylated fibers achieved higher MOF loading. Photocatalytic experiments under simulated solar irradiation demonstrated significantly higher degradation of acetaminophen when the carboxylated cotton fabric-based catalyst (F-COOH-UiO-66-NH₂) was used. Mott–Schottky analysis and band alignment revealed that, under the applied reaction conditions, hydroxyl radical generation was not favored due to the position of the valence band. Studies with scavengers identified the superoxide radical as the dominant oxidative agent responsible for the photodegradation process. In particular, the F-COOH-UiO-66-NH₂ system demonstrated its suitability for application in continuous flow systems, achieving acetaminophen conversion of up to 50% under simulated solar irradiation. This confirms its potential for scalable application in practical water treatment technologies. These results reinforce the feasibility of immobilizing MOF-based photocatalysts on functionalized textile waste, offering a dual-purpose solution that combines the removal of pharmaceutical pollutants with the valorization of waste materials. The synergistic integration of high photocatalytic efficiency, sunlight harvesting and recyclability of the materials underlines the eco-friendly and cost-effective nature of the proposed strategy. Full article

β-agonists are prohibited antibiotics that have raised concerns due to their illegal use in the livestock industry, posing potential toxicity risks to human health. For ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) analysis of β-agonists, effective sample pretreatment is a crucial and challenging process that dictates the overall reliability and sensitivity of the method. Thus, this study developed a reliable method utilizing dispersive solid-phase extraction (d-SPE) with NH₂-UiO-66 as a superior adsorbent, coupled with UPLC-MS/MS, to extract and quantify β-agonists in environmental water, swine urine, and milk. The synthesized NH₂-UiO-66 exhibited outstanding adsorption capacities (146.06–358.00 mg/g) towards the target analytes. The optimized method demonstrated excellent performance: low matrix effects (−13.10–15.30%), wide linearity (0.1–50 μg/L), low limits of detection (0.04–0.09 μg/L), and satisfactory recoveries (81.48–106.67%) with good precision (intra-day RSDs 1.51–6.24%; inter-day RSDs 2.06–10.96%). Adsorption mechanism studies revealed that the extraction process, which followed the Langmuir isotherm and pseudo-second-order kinetic models, was driven primarily by electrostatic interactions, π-π stacking, and hydrogen bonding. Moreover, the material could be reused up to 10 times, with satisfactory recoveries of 81.30% to 116.10%. The proposed NH₂-UiO-66-d-SPE-UPLC-MS/MS protocol is generic and provides a robust and practical solution for monitoring trace β-agonists in animal-derived foods and environmental samples, ensuring food safety and environmental health. Full article

This study investigates the synthesis, dual functional applications, and electrochemical performance of the amine-functionalized metal-organic framework (MOF), namely UiO-66-NH₂. The material was synthesized via the solvothermal method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning and transmission electron microscopy (SEM/TEM). UiO-66-NH₂ was assessed as a catalyst for the reduction of nitroarenes, specifically 2-nitrophenol (2-NP) and 4-nitrophenol (4-NP), under both dark and photo-assisted (i.e., photocatalysis) conditions. Complete photoreduction of nitroarenes was achieved under photocatalysis, highlighting its photo-assisted catalytic efficacy. UiO-66-NH₂ before and after nitroarenes adsorption capacities were investigated, and subsequent electrochemical assessments confirmed its suitability as a supercapacitor electrode. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) analyses demonstrated that nitroarene adsorption and light irradiation markedly improved specific capacitance. 2-NP@UiO-66-NH₂ showed specific capacitance of 221 F/g at 1 A/g under UV radiation. UiO-66-NH₂ demonstrated remarkable cycling stability (100%) across 7000 cycles. Structural and property modifications of UiO-66-NH₂, adsorption of redox-active species, and photo-assisted mechanisms can significantly enhance the energy storage efficacy. The results illustrate the dual role of UiO-66-NH₂ as an effective photo-assisted catalyst and electroactive supercapacitor material, facilitating integrated environmental remediation and energy storage applications. Full article

Arsenic contamination in water remains a critical global health challenge, affecting millions and causing severe diseases including cancer, skin lesions, and cardiovascular disorders. Adsorption using metal–organic frameworks (MOFs), particularly zirconium-based UiO-66 and its derivatives, offers a promising and sustainable approach for arsenic remediation due to their high surface area, tunable porosity, and strong chemical stability. Functionalized UiO-66 variants (e.g., –NH₂, –SO₃H, –COOH, –SH), metal-doped, or composite forms such as Fe₃O₄@UiO-66 exhibit arsenic adsorption capacities between 20 and 150 mg g⁻¹, depending on synthesis and surface chemistry. Optimal adsorption occurs within pH 4–8, while high salinity or competing anions reduce performance by 15–40%. UiO-66 materials demonstrate excellent regeneration efficiency (70–95%) after multiple cycles, with limited metal leaching (1–3%). Advances through ligand functionalization, modulator-assisted synthesis, and composite integration have significantly improved adsorption capacity, selectivity, and reusability. However, challenges persist in achieving green, water-based synthesis, maintaining long-term stability under realistic water chemistries, and enabling scalable production. Future work should focus on eco-friendly fabrication, defect engineering, and mechanistic optimization to fully harness UiO-66’s potential as a high-performance and sustainable adsorbent for arsenic-contaminated water treatment. Full article

Gentamicin (GEN) is a broad-spectrum antibiotic widely used in livestock production, and its excessive residues in animal-derived foods pose potential health risks to consumers. However, conventional colloidal gold immunochromatographic assays (AuNPs-ICA) often suffer from low sensitivity and poor tolerance to sample matrices. Herein, a UiO-66-NH₂ framework decorated with gold nanoparticle (UiO-66-NH₂@Au)-based ICA was employed to construct an ICA platform for GEN detection, combining the optical advantages of AuNPs with the protective and stable octahedral framework of the Metal-organic framework (MOF) to enhance antibody stability under extreme conditions. The method achieved limits of detection for GEN of 0.1 µg/kg in four tested matrices, with recoveries of 80.1–112.0% and coefficients of variation below 11.7%. Compared to traditional AuNPs-ICA, the sensitivity was improved by up to 30-fold, the pH tolerance range was expanded from 6–8 to 4–10, and the organic solvent tolerance to organic solvents expanded up to 40%. Verification with 40 real samples demonstrated excellent correlation (R² > 0.99) with results from commercial ELISA kits. This UiO-66-NH₂@Au-ICA platform offers a new technical solution with high sensitivity, strong good anti-interference performance, and robustness for rapid field detection of GEN residues in products of animal origin and holds significant practical importance for advancing rapid food safety detection technologies. Full article

The efficient separation of light hydrocarbons, particularly alkanes from their isomers (C₅–C₆), represents a significant and energy-intensive challenge for the petrochemical industry. Metal-Organic Frameworks (MOFs) offer promising solutions due to their exceptional porosity, surface area, and, crucially, their structural and chemical tunability. This study employs advanced computational methods, including Grand Canonical Monte Carlo (GCMC) simulations and Molecular Dynamics (MD), to systematically investigate the adsorption and separation of pentane isomers (n-pentane, isopentane, and neopentane) in the UiO-66 MOF family. Specifically, the impact of organic linker functionalization with -H (parent), -NH₂, -CH₃, and -COOH groups on adsorption isotherms, isosteric heats, and competitive behavior in mixtures is evaluated. The analysis provides a molecular-level view of host-guest and guest-guest interactions, elucidating the recognition and selectivity mechanisms governing the separation of these C5 isomers and the potential for engineering MOF materials for this application. Full article

Objective: This study aims to develop a metal–organic framework (ABZ-MOFs)-based oral drug delivery system for albendazole (ABZ) to enhance its dissolution rate and oral bioavailability. Methods: ABZ@MOF-802, ABZ@UiO-66-NH₂, and ABZ@MIL-125-NH₂ were synthesized using a solvothermal method, and their physicochemical properties were characterized. The in vitro drug release was investigated under pH- and enzyme-responsive conditions, followed by transmembrane transport studies in Caco-2 cells. Finally, the oral bioavailability of ABZ@MOFs was evaluated in rats. Results: The particle sizes of ABZ@MOF-802, ABZ@UiO-66-NH₂, and ABZ@MIL-125-NH₂ were (1062.6 ± 94.8), (228.3 ± 12.3), and (502.3 ± 16.2) nm, with drug loading efficiencies of (1.71 ± 0.08%), (12.13 ± 0.04%), and (26.17 ± 0.10%), respectively. The ABZ@MOFs demonstrated structural stability in acidic environments and released ABZ under weakly acidic and neutral conditions, exhibiting distinct release profiles in the presence of different enzymes. Cellular experiments confirmed that ABZ@MOFs significantly improved transmembrane drug absorption. Pharmacokinetic analysis revealed that the bioavailability of ABZ@UiO-66-NH₂ and ABZ@MIL-125-NH₂ was 10.3-fold and 1.8-fold higher, respectively, compared to ABZ. Conclusions: The ABZ@MOFs systems effectively improved ABZ dissolution and oral bioavailability, with ABZ@UiO-66-NH₂ showing a dual response mechanism to pH and enzymes. Full article

UiO-66-NH₂ is a metal–organic framework (MOF) with open metal sites, making it a promising candidate for adsorption and catalysis. However, the powdery texture of MOFs and the use of toxic solvents during synthesis limit their application. A novel solution to this issue is to create a layered porous composite by encasing the MOF within a flexible and structurally robust aerogel substrate using safe, eco-friendly, and green solvents such as ethanol. The fibrous MOF aerogels, characterized by a desirable macroscopic shape of cylindrical block and hierarchical porosity, were synthesized by two approaches: in situ growth of amine-functionalized UiO-66-NH₂ crystals on a TEMPO-oxidized cellulose nanofiber (TOCNF) and ex situ crosslinking of UiO-66-NH₂ crystals onto a TOCNF network to form UiO-66-NH₂/TOCNF. The incorporation of MOF into the cellulose nanofibrils via the in situ method reduces their aggregation potential, alters the nucleation/growth balance to produce smaller MOF crystals, and enhances mechanical flexibility, as evidenced by SEM images. The three adsorbents, including UiO-66-NH₂, ex situ UiO-66-NH₂/TOCNF, and in situ UiO-66-NH₂/TOCNF, were synthesized and used in this study. The effects of pH, time, temperature, and initial concentration were studied. A maximum adsorption capacity (Qmax) of 549.45 mg/g for Congo Red (CR) and 171.23 mg/g for Orange II (ORII) was observed at pH 6, using 10 mg of in situ UiO-66-NH₂/TOCNF at 40 °C with a contact time of 75 min for CR and 2 h for ORII. The adsorption of both dyes primarily occurs through monolayer chemisorption on the in situ UiO-66-NH₂/TOCNF. The main removal mechanisms were hydrogen bonding and surface complexation. The noteworthy adsorption capacity of in situ UiO-66-NH₂/TOCNF coupled with environment-friendly fabrication techniques indicates its potential applications on a large scale in real wastewater systems. Full article

Air pollutants, such as particulate matter (PM) and ammonia (NH₃), generated by intensive animal farming pose considerable threats to human health, animal welfare, and ecological balance. Conventional materials are often ineffective at simultaneously removing multiple pollutants, maintaining a low pressure drop, and ensuring durability in heavily polluted environments. Inspired by the dust-retention properties of Pinus sylvestris var. mongolica (PS) needles, this study developed a biomimetic grooved ribbon fiber using electrospinning technology. These fibers were further assembled into a three-dimensional bioinspired aerogel structure through freeze-forming technology to achieve efficient dust capture. Additionally, the introduction of UiO-66-NH₂ nanoparticles significantly enhanced the properties of the aerogels for NH₃ adsorption. Among the various prepared aerogels (PG, UPG-5, UPG-10, UPG-15, and UPG-20), UPG-10 demonstrated the best performance, achieving a filtration efficiency of 99.24% with a pressure drop of 95 Pa. Notably, it exhibited a remarkable dust-holding capacity of 147 g/m², and its NH₃ adsorption capacity reached 99.89 cm³/g, surpassing PG aerogel by 31.46 cm³/g. Additionally, UPG-10 exhibited outstanding elasticity, maintaining over 80% of its original shape after 30 compression cycles. This biomimetic aerogel presents a promising solution for air purification, contributing to improved agricultural efficiency and environmental sustainability. Full article

In this study, a Brönsted–Lewis bifunctional acidic catalyst PW/UiO/CNTs-OH was synthesized via the hydrothermal method. The parameters for the esterification reaction of oleic acid with methanol catalyzed by PW/UiO/CNTs-OH were optimized using central composite design-response surface methodology (CCD-RSM). A biodiesel yield of 92.9% was achieved under the optimized conditions, retaining 82.3% biodiesel yield after four catalytic cycles. The enhanced catalytic performance of PW/UiO/CNTs-OH can be attributed as follows: the [Zr₆O₄(OH)₄]¹²⁺ anchored on the surface of multi-walled carbon nanotubes (MWCNTs) can serve as nucleation sites for UiO-66, not only encapsulating H₃[P(W₃O₁₀)₄] (HPW) but also reversing the quadrupole moment of MWCNTs to generate Lewis acid sites. In addition, introduction of HPW during synthesis of UiO-66 decreases the solution pH, inducing the protonation of p-phthalic acid (PTA) to disrupt the coordination with the [Zr₆O₄(OH)₄] cluster, thereby creating an unsaturated Zr⁴⁺ site with electron pair-accepting capability, which generates Lewis acid sites. EIS analysis revealed that PW/UiO/CNTs-OH has higher electron migration efficiency than UiO-66 and PW/UiO. Furthermore, NH₃-TPD and Py-IR analyses showed that PW/UiO/CNTs-OH possessed high densities of Lewis acidic sites of 83.69 μmol/g and Brönsted acidic sites of 9.98 μmol/g. Full article