Search Results (127)

Water scarcity poses a formidable challenge around the world, especially in arid regions where limited availability of freshwater resources threatens both human well-being and ecosystem sustainability. Membrane-based desalination technologies offer a viable solution to address this issue by providing access to clean water. This work ultimately aims to develop a novel permselective polymeric membrane material to be employed in an electrochemical desalination system. This part of the study addresses the optimization, preparation, and characterization of a polyvinylidene difluoride (PVDF) polymeric membrane using the electrospinning technique. The membranes produced in this work were fabricated under specific operational, environmental, and material parameters. Five different additives and nano-additives, i.e., graphene oxide (GO), carbon nanotubes (CNTs), zinc oxide (ZnO), activated carbon (AC), and a zeolitic imidazolate metal–organic framework (ZIF-8), were used to modify the functionality and selectivity of the prepared PVDF membranes. Each membrane was synthesized at two different levels of additive composition, i.e., 0.18 wt.% and 0.45 wt.% of the entire PVDF polymeric solution. The physiochemical properties of the prepared membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), zeta potential, contact angle, conductivity, porosity, and pore size distribution. Based on findings of this study, PVDF/GO membrane exhibited superior results, with an electrical conductivity of 5.611 mS/cm, an average pore size of 2.086 µm, and a surface charge of −38.33 mV. Full article

Volatile organic compounds (VOCs) are presently posing a rather considerable threat to both human health and environmental sustainability. Among these, n-butanol is commonly identified as bringing potential hazards to environmental integrity and individual health. This study presents the creation of a highly sensitive n-butanol gas sensor utilizing cobalt-doped zinc oxide (ZnO) derived from a metal–organic framework (MOF). A series of x-Co/MOF-ZnO (x = 1, 3, 5, 7 wt%) nanomaterials with varying Co ratios were generated using the homogeneous co-precipitation method and assessed for their gas-sensing performances under a low operating temperature (191 °C) and UV excitation (220 mW/cm²). These findings demonstrated that the 5-Co/MOF-ZnO sensor presented the highest oxygen vacancy (O_v) concentration and the largest specific surface area (SSA), representing the optimal reactivity, selectivity, and durability for n-butanol detection. Regarding the sensor’s response to 100 ppm n-butanol under UV excitation, it achieved a value of 1259.06, 9.80 times greater than that of pure MOF-ZnO (128.56) and 2.07 times higher than that in darkness (608.38). Additionally, under UV illumination, the sensor achieved a rapid response time (11 s) and recovery rate (23 s). As a strategy to transform the functionality of ZnO-based sensors for n-butanol gas detection, this study also investigated potential possible redox reactions occurring during the detection process. Full article

A novel single-walled carbon nanotube (SWNT), silver (Ag) nanoparticle, and zinc benzene carboxylate (ZnBDC) metal–organic framework (MOF) composite was synthesised and systematically characterised to develop an efficient platform for mercury ion (Hg²⁺) detection. X-ray diffraction confirmed the successful incorporation of Ag nanoparticles and SWNTs without disrupting the crystalline structure of ZnBDC. Meanwhile, field-emission scanning electron microscopy and energy-dispersive spectroscopy mapping revealed a uniform elemental distribution. Thermogravimetric analysis indicated enhanced thermal stability. Electrochemical measurements (cyclic voltammetry and electrochemical impedance spectroscopy) demonstrated improved charge transfer properties. Electrochemical sensing investigations using differential pulse voltammetry revealed that the SWNTs/Ag@ZnBDC-modified glassy carbon electrode exhibited high selectivity toward Hg²⁺ ions over other metal ions (Cd²⁺, Co²⁺, Cr³⁺, Fe³⁺, and Zn²⁺), with optimal performance at pH 4. The sensor displayed a linear response in the concentration range of 0.1–1.0 nM (R² = 0.9908), with a calculated limit of detection of 0.102 nM, slightly close to the lowest tested point, confirming its high sensitivity for ultra-trace Hg²⁺ detection. The outstanding sensitivity, selectivity, and reproducibility underscore the potential of SWNTs/Ag@ZnBDC as a promising electrochemical platform for detecting trace levels of Hg2+ in environmental monitoring. Full article

Objective: Fluoride is widely recognized for its preventive role against secondary caries. This systematic review aimed to evaluate how environmental and material factors influence fluoride ion release from metal-reinforced glass ionomer cements. Methods: A structured literature search was performed in March 2025 across PubMed, Scopus, and Web of Science databases. Search terms included combinations of fluoride release AND glass ionomer AND silver OR zinc OR strontium OR copper. The study selection process followed PRISMA 2020 guidelines and was organized using the PICO framework. Out of 281 initially identified records, 153 were screened based on titles and abstracts. After applying predefined eligibility criteria, 23 studies met the inclusion requirements and were included in the qualitative analysis. Results: Among the 23 included publications, 12 involved glass ionomers modified with silver, and 6 of these reported an increase in fluoride release. Seven studies focused on zinc-modified cements, and four examined materials reinforced with strontium. Conclusions: The addition of strontium, titanium oxide, silver nanoparticles, or zirconium oxide increases the release of fluoride ions, while sintered silver reduces it. There is a great discrepancy among researchers regarding the effect of the addition of zinc oxide and its appropriate amount in the glass ionomer material. Full article

A novel metal–organic framework based on zinc ions, designated as Zn-URJC-12, has been synthesized and applied for the first time in the cycloaddition reaction between carbon dioxide and epoxides. This MOF is constructed from two different organic linkers: 5-aminoisophthalic acid and 4,4′-biphenyldicarboxylic acid. The framework features –NH₂ functional groups coordinated to Zn(II) centers, as confirmed by single-crystal X-ray diffraction analysis. Zn-URJC-12 demonstrates exceptional chemical stability in polar organic solvents, such as methanol, while maintaining thermal stability up to 250 °C. The material exhibits high catalytic efficiency in the cycloaddition of CO₂ with epoxides, achieving yields of 100% and 76% for propylene oxide and allyl glycidyl ether, respectively. Additionally, Zn-URJC-12 maintains its structural integrity and catalytic performance during five successive reaction cycles. These findings underscore Zn-URJC-12 as a promising heterogeneous catalyst for the valorization of CO₂ into cyclic carbonates. Full article

Materials derived from metal–organic frameworks (MOFs) as MOF-derived oxides retain a highly porous and active structure from the MOF precursor, exhibiting excellent sensing properties. In addition, the tunable nature of MOFs allows the structural and chemical properties of the resulting oxides to be specifically tuned to enhance their performance as sensing materials. In this work, zinc-based MOF structures belonging to the family of zeolitic imidazolate frameworks (ZIFs) were synthesized, characterized and then subjected to a high-temperature calcination process to obtain the corresponding oxides. To improve sensing performance, various silver doping strategies (1 wt.%) were explored, specifically through a growth process and an impregnation process. Among these approaches, the oxide obtained via the growth process demonstrates superior performance, exhibiting a response 5.8 times higher than pristine ZnO when exposed to 80 ppm of ethanol at 300 °C in a humidity-controlled chamber. These results highlight the potential of silver doping via growth process as an effective strategy to enhance the sensing performance of MOF-derived ZnO. Full article

Evaluating the bioaccessibility and health risks of seafood is extremely important because, although it is a significant source of vital minerals, it may also contain potentially toxic elements. This study aimed to determine the content of metals and minerals in different seafood species before and after thermal processing. Also, given the risk of overestimating the actual final concentration available in the body, a study was carried out to determine the bioaccessibility of these elements by simulating the digestion process in the gastrointestinal tract. Assessment of the potential toxic effects on consumer health in terms of exposure to heavy metals was carried out through risk analysis by Estimated Daily Intake, Hazard Index, and Cancer Risk parameters. Three bivalve mollusks, one gastropod mollusk, four cephalopod mollusks, and one crustacean species were analyzed in terms of minerals (P, S, K, Ca, and Se) and heavy metals (Cd, Pb, Ni, Cr, Fe, Zn, Co, Mn, and As) content. The lead (Pb) concentration recorded the strongest bioaccessibility increase, even reaching 100% in P. vannamei. Generally, the bioaccessibility of all metalloids dropped below 100%, which suggests that only a part of the amount of metal in the initially ingested sample can be absorbed by the human organism. Potassium and sulfur registered the greatest value, up to 23% for minerals’ bioaccessibility in the same samples. The highest intake rate of metals occurred after the consumption of M. gigas, which registered the highest Estimated Daily Intake for Cr (chromium) (0.321 mg kg⁻¹ d⁻¹), Cu (copper) (10.15 mg kg⁻¹ d⁻¹), and Zn (zinc) (12.67 mg kg⁻¹ d⁻¹). The Hazard Index values indicated no significant risk of poisoning. All calculated Cancer Risk scores remained below the acceptable threshold. Moreover, the Pearson coefficient revealed a positive correlation between the Hazard Index and the most abundant elements in the samples, Cr, Zn, and Cu. This study could provide a framework for evaluating both the nutritional benefits and toxicological concerns of seafood intake in public health applications. Full article

In this study, a Zn(CN)₂–V₂O₃–C composite cathode was synthesized via AC electrophoretic deposition (EPD) and evaluated for application in aqueous zinc-ion batteries (ZIBs). Here, we report for the first time a binder-free Zn(CN)₂–V₂O₃–C composite cathode, using AC-EPD to create an ultrathin architecture optimized for probing the electrode–electrolyte interface without interference from additives or bulk effects. The composite combines Zn(CN)₂ for structural support, V₂O₃ as the redox-active material, and carbon for improved conductivity. X-ray diffraction confirmed the presence of Zn(CN)₂ and V₂O₃ phases, while scanning electron microscopy revealed a uniform, ultrathin film morphology. Electrochemical analysis demonstrated a hybrid charge storage mechanism with a b-value of 0.64, indicating both capacitive and diffusion-controlled contributions. The electrode delivered a high specific capacity (~250 mAh/g at 500 mA/g) with stable cycling performance. These results highlight the potential of metal–organic framework-derived composites for high-performance ZIB cathodes. The composite is especially effective when prepared via AC-EPD, which yields ultrathin, uniform films with strong adhesion and low agglomeration. This enhances energy storage performance and provides a reliable platform for focusing on interfacial charge storage, excluding the effect of binders on electrochemical performance. Full article

Paper and cellulose-based materials are known for their sensitivity to humidity, which can create stresses among fibres and increase fragility. More importantly, humidity can lead to the formation of mould and stains, compromising both aesthetic value and long-term preservation, particularly for historical documents and books. This study explored the application of in situ prepared Zeolitic Imidazolate Framework (ZIF-8), a zinc-based MOF, on paper as a potential antimicrobial material. Hand-made and commercially printed papers were tested to assess the effective deposition and formation of the ZIF-8 network, with a focus on both visual appearance and physicochemical characteristics. X-ray fluorescence and diffraction, infrared spectroscopy, and scanning electron microscopy analysis confirmed the successful formation of the ZIF-8 network in all papers. The Zn content varied, as expected, depending on application time and paper characteristics. All treated papers exhibited minor variations in brilliance and showed slightly increased rigidity. The formation of white spots linked to Zn accumulation was observed, particularly in printed books where colourimetric and microscopic variations were more pronounced. Full article

Developing efficient and durable non-precious metal catalysts for oxygen electrocatalysis in fuel cells and zinc–air batteries remains an urgent issue to be addressed. Herein, a bimetallic CoCe-NC catalyst is synthesized through pyrolysis of Co/Ce co-doped metal–organic frameworks (MOFs), retaining the inherently high surface area of MOFs to maximize the exposure of Co-N and Ce-N active sites. The electronic interaction between Co and Ce atoms effectively modulates the adsorption/desorption behavior of oxygen-containing intermediates, thereby enhancing intrinsic catalytic activity. In alkaline media, the CoCe-NC catalyst exhibits E_1/2 = 0.854 V electrocatalytic capability comparable to commercial Pt/C, along with superior methanol resistance and durability. Notably, CoCe-NC demonstrates an overpotential 84 mV lower than Pt/C at 300 mA cm⁻² in a GDE half-cell. When the catalyst is employed as a cathode in zinc–air batteries, it demonstrates an open-circuit voltage of 1.47 V, a peak power density of 202 mW cm⁻², and exceptional cycling durability. Full article

A metal–organic framework, MOF-S1, was synthesized via a solvothermal reaction between 2,4,6-tris-(4-carboxyphenoxy)-1,3,5-triazine (TCPT) and zinc nitrate hexahydrate. Single-crystal and powder X-ray diffraction analyses confirmed the formation of hexagonal rod-shaped crystals with a trigonal (P-31c) structure featuring a two-fold interpenetrated 3D framework. A comprehensive characterization—including NMR spectroscopy, thermogravimetric analysis, and surface area measurements (using Langmuir, t-plot, Horváth–Kawazoe, and Dubinin–Radushkevich models)—revealed an ultramicroporous material with a Langmuir surface area of 711 m²/g and a median pore width of ~6.5 Å. Adsorption studies using Congo Red, Methylene Blue, Methyl Orange, and Rhodamine B demonstrated the rapid uptake and effective removal from aqueous solutions, with kinetic modeling indicating a dominant chemisorption mechanism. Photocatalytic tests under UV irradiation yielded degradation efficiencies of ~93% for Methyl Orange and ~74% for Rhodamine B. These findings suggest that MOF-S1 is a promising candidate for wastewater treatment applications and UV-related processes, offering a strong adsorption capacity and thermal stability. Full article

Compared to conventional adsorbents, zinc-based metal–organic frameworks (MOFs) such as zeolite imidazolium skeleton-8 (ZIF-8) exhibit enhanced thermal, chemical, and structural stability. Nonetheless, their powdered form results in limited dispersibility in aqueous solutions and a tendency to aggregate, which significantly restricts their utility in adsorption applications. This study reports a green composite aerogel through the in situ mineralization of ZIF-8 onto bacterial cellulose (BC) for the effective removal of toxic metal ions (Cu²⁺) and Congo red (CR) from wastewater. The ZIF@BC composite aerogel was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and specific surface area analysis. The findings indicated that the ZIF-8 produced were evenly distributed across the BC nanonetwork, facilitating effective adsorption of CR and Cu²⁺. The maximum adsorption capacities of the ZIF@BC aerogels were determined to be 397.55 mg/g for CR and 424.80 mg/g for Cu²⁺, as per the Langmuir isotherm. Furthermore, the ZIF-8@BC aerogels demonstrated excellent selectivity and reusability, particularly for CR adsorption. The proposed mechanism for the interaction between the composite aerogel and CR and Cu²⁺ involves electrostatic interactions, hydrogen bonding, π-π bonding, coordination bonding, ion exchange, microchemical precipitation, and pore diffusion. This research offers significant promise for the utilization of MOF powders and highlights substantial industrial potential. Full article

Triazine-based covalent organic framework CTF-1 was synthesized via polymerization of 1,4-dicyanobenzene in the presence of zinc chloride. Two different methods of the post-synthesis treatment of the obtained material were compared. It was demonstrated that ultrasonication effectively removes impurities from CTF-1. Adsorption of hydrocarbon gases (methane and ethane) and carbon dioxide was measured at 298 K in a wide pressure range for the first time. Ideal selectivity and IAST values for methane/ethane and methane/CO₂ pairs were calculated from the obtained isotherms. Full article

There is much promise for creating metal organic framework (MOF) films on metal substrates in fields including sensing and electrical conduction. For these applications, direct production of MOF films with strong bonding on metal substrates is extremely desirable. In this study, a simple one-step method without the need for additives or pre-modification is used to directly create zeolitic imidazolate framework-8 (ZIF-8) films with strong bonding on zinc substrate. The formation mechanisms of ZIF-8 film are analyzed. The strong bonding ZIF-8 film can be attributed to an in-situ grown ZnO interlayer between the ZIF-8 and substrate. The growth process shows the formation time of zinc oxide on the substrate, which is subsequently covered by ZIF-8 crystals. The ZnO interlayer results from a combination of decomposition products of the solvent and the zinc ions. Furthermore, the ZnO interlayer serves as a sacrificial precursor for the in-situ nucleation and continuous growth of ZIF-8 film. It serves as an anchoring site between ZIF-8 film and substrate, resulting in strong adhesion. This paper describes a simple and straightforward production process that is expected to provide a theoretical basis for the laboratory preparation of ZIF films. Full article

Metal air batteries have gradually attracted public attention due to their advantages such as high power density, high energy density, high energy conversion efficiency, and clean and green products. Reasonable design of oxygen reduction reaction (ORR) catalysts with high cost-effectiveness, high activity, and high stability is of great significance. Metal organic frameworks (MOFs) have the advantages of large specific surface area, high porosity, and designability, which make them widely used in many fields, especially in catalysis. This paper starts with regulating and optimizing the composition and structure of MOFs. A series of N, S co-doped electrocatalysts FeCuS-N-C were prepared by two high-temperature pyrolysis processes using N-doped carbon hollow nanorods derived from ZIF-8 as the substrate. The one-dimensional nanorod material derived from this MOF exhibits excellent electrocatalytic ORR performance (Eonset = 0.998 V, E_1/2 = 0.874 V). When used as the air cathode catalyst for zinc air batteries and assembled into liquid ZABs, the battery discharge curve was calculated and found to have a maximum power density of 142.7 mW cm⁻², a specific capacity of 817.1 mAh gZn⁻¹, and a cycling stability test of over 400 h. This study provides an innovative approach for designing and optimizing non-precious metal catalysts for zinc air batteries. Full article