Novel ZIF-8/CNC Nanohybrid with an Interconnected Structure: Toward a Sustainable Adsorbent for Efficient Removal of Cd(II) Ions

Multifunction hydrogen-bonded organic framework aerogel platform for detection and removal of heavy metal ions in pear juice

Heavy metal ions (HMIs) in food pose significant health risks due to their bioaccumulation and toxicity, necessitating effective detection and remediation methods. This study explores a multifunctional hydrogen-bonded organic framework (HOF-16) wrapped in sodium alginate (SA) to form a stable HOF-16/SA aerogel for detecting and removing HMIs in pear juice. The HOF-16 fluorescence probe exhibits excellent sensitivity with limits of detection of 0.49, 0.60, and 0.44 μmol/L for Pb(II), Cu(II), and Cd(II), respectively. The maximum adsorption capacities of HOF-16/SA aerogel for Pb(II), Cu(II), and Cd(II) are 284.69, 248.08, and 183.94 mg/g, respectively. The removal efficiency of HOF-16/SA aerogel for HMIs in pear juice exceeds 98 % without negative impacts. Sensitive detection of HMIs is attributed to the fluorescence quenching effect caused by electron transfer, while electrostatic interactions and complexation enhance the effective adsorption performance. This study provides a HOF-aerogel platform with great potential for detecting and removing HMIs from food matrix.

Facile fabrication of electrospun hybrid nanofibers integrated cellulose, chitosan with ZIF-8 for efficient remediation of copper ions

To removal copper ions (Cu2+) from wastewater, structurally stable microcrystalline cellulose (MCC)/chitosan (CS)/zeolitic imidazole framework-8 (ZIF-8) hybrid nanofibers were fabricated by mixing electrospinning (MCC/CS/ZIF-8) and in-situ grown of ZIF-8 on electrospun nanofibers (I-MCC/CS/ZIF-8). The microstructure, porosity, thermal stability, crystal structure, surface wettability, chemical groups of hybrid nanofibers as well as their adsorption performance, isotherms, and kinetics were characterized and analyzed. The rhombohedral ZIF-8 at the optimum synthesis ratio was evenly bounded to nanofibers, corresponding to an average diameter of 775.81 nm. The introduction of ZIF-8 effectively improved the thermal stability of biomass polysaccharide nanofibers, maintained beneficial hydrophilicity (25.08°), increased their specific surface area by 16.51 times, and provided abundant potential active sites for Cu2+ adsorption. The adsorption performance of I-MCC/CS/ZIF-8 was superior to that of MCC/CS/ZIF-8, achieving the maximum Cu2+ adsorption capacity of 204.08 mg g-1 at pH = 5, which conformed to both the Langmuir model and the pseudo-second-order kinetic model. The enhanced mechanism for Cu2+ adsorption can be attributed to the sufficient channels of porous network and the strong hydrogen bonding facilitating physical adsorption, as well as the effective chemical adsorption resulting from the rapid growth of ultrathin lamellar copper oxide‑zinc oxide heterojunctions with nanoflower-like shapes.

Effective Removal of Tetracycline from Water Using Stable MOF-808: A Comprehensive Investigation on Activation, Stability, and Influencing Parameters

Tetracycline (TC) is a widely utilized antibiotic that raises significant environmental concerns. Therefore, the implementation of effective removal strategies is imperative to mitigate its environmental impacts. This study investigates the adsorption of TC from aqueous solutions using MOF-808, synthesized via a solvothermal method. Two activation techniques, Soxhlet extraction and centrifugation, were applied to optimize the properties of the synthesized MOF-808, resulting in materials designated as S-MOF-808 and C-MOF-808, respectively. Comparative studies have demonstrated that S-MOF-808 shows superior adsorption due to its higher Brunauer-Emmett-Teller (BET) surface area of 1062 m2 g-1, compared to 622 m2 g-1 for C-MOF-808. The experimental adsorption results for both MOF-808s followed the pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacities for TC were determined to be approximately 333.33 mg g-1 for S-MOF-808 and 312.50 mg g-1 for C-MOF-808, underscoring the optimal performance of S-MOF-808 in adsorption applications. Moreover, chemical stability was assessed over two months, with X-ray diffraction (XRD) analysis showing that S-MOF-808 maintained superior structural integrity compared to C-MOF-808. These findings highlight the potential of S-MOF-808 as a robust and efficient adsorbent for removing TC from complex aqueous environments, featuring its suitability for environmental remediation applications.

Green Synthesis of Nano-Sized Multiflower-like Fe3O4@SiO2/L-Tryptophan from Natural Resources and Agricultural Waste: A Photo-Switchable Oxidation Catalyst

This study presents a novel, eco-friendly, and cost-effective magnetic hybrid photocatalyst, Fe3O4@SiO2/L-tryptophan, synthesized through a scalable three-step green approach using natural and agricultural waste. The Fe3O4@SiO2/L-tryptophan nanoparticle features a core-shell structure with a high surface area (63.14 m2/g), strong visible-light absorption (λ > 448 nm), a narrow band gap (1.84 eV), and superparamagnetic properties (22 emu/g), enabling efficient separation and reusability. Characterization techniques (XRD, XPS, FT-IR, FE-SEM, HR-TEM, UV-vis DRS, TGA, BET, and EIS) confirmed its structural stability, charge separation, and interfacial charge transport. The photocatalyst achieved 82.1% oxidative desulfurization of dibenzothiophene (DBT) and high conversion rates for toluene (85%) and styrene (90%) under visible light using O2 as an oxidant. It retained over 85% activity after five cycles, demonstrating excellent durability. For the first time, all components are derived from natural sources: Fe3O4 from sorghum seed extract, SiO2 from rice husk, and L-tryptophan for enhanced light absorption and charge separation. This sustainable synthesis reduces chemical waste and energy consumption, setting a new benchmark for environmentally friendly photocatalysts.

A Targeted Core-Shell ZIF-8/Au@Fe3O4 Platform with Multiple Antibacterial Pathways for Infected Skin Wound Regeneration

Bacterial infections seriously retard skin wound healing. To enhance the antibacterial efficiency and subsequent skin regeneration, a core-shell structured therapeutic platform, named FZAM, was designed with multiple antimicrobial pathways. FZAM consists of nanosized Fe3O4 as the core and ZIF-8 loaded with Au nanoparticles (NPs) and maltodextrin as the shell. Fe3O4 and Au NPs form a heterojunction that generates hyperthermia and abundant reactive oxide species (ROS) under near-infrared (NIR) irradiation. This heterojunction also exhibits outstanding peroxidase-like activity. When bacteria invade, maltodextrin plays a targeting effect to increase the interaction between FZAM and bacteria, and with the synergistic action of NIR-induced hyperthermia and ROS as well as Zn2+ from ZIF-8, FZAM kills more than 99% of bacteria at 200 μg mL-1. Fortunately, FZAM is cytocompatible and even promotes the biofunctions of fibroblasts and endothelial cells. In infected skin wound models, FZAM sterilizes bacteria with NIR irradiation and subsequently reduces the inflammatory response and accelerates skin regeneration. This work provides a core-shell structured therapy platform for treating infection with the assistance of NIR irradiation and helping skin wound healing.

Curcumin delivery system based on a chitosan-liposome encapsulated zeolitic imidazolate framework-8: a potential treatment antioxidant and antibacterial treatment after phacoemulsification

Curcumin is a natural polyphenol extracted from plants that can interact with various molecular targets, including antioxidant, antibacterial, anticancer, and anti-aging activities. Due to its variety of pharmacological activities and large margin pf safety, curcumin has been used in the prevention and treatment of various diseases, such as Alzheimer's, heart, and rheumatic immune diseases. To develop curcumin eye drops that can be used as antioxidant and antibacterial agents after phacoemulsification, we have designed a nano-based drug delivery system to improve curcumin bioavailability and duration of action. We successfully prepared zeolitic imidazolate framework-8 (ZIF-8) coated with chitosan-liposome (Cur@ZIF-8/CS-Lip) for curcumin delivery. It can release curcumin for over 20 hin vitroand exhibits excellent biosafety, antioxidant, and antibacterial activities. Therefore, we hypothesized that Cur@ZIF-8/CS-Lip could reduce the incidence of oxidative stress and infection after cataract surgery.

Investigation the effect of exchange solvents on the adsorption performances of Ce-MOFs towards organic dyes

Cerium-based MOFs (Ce-MOFs) are regarded as attractive porous materials showing various structures, excellent thermal and chemical stability, tunable porous properties, and simple synthetic methods that are useful for wastewater treatment applications. Hence, in the present work, we synthesized a series of Ce-MOFs through a fast and green synthetic method at room temperature using water as a green solvent. Four different solvents including ethanol, chloroform, acetone, and methanol were used in the solvent-exchange process to engineer the properties of prepared Ce-MOFs. The influence of different exchange solvents on the crystalline structure, porous structure, thermal stability, and surface morphology of Ce-MOFs was studied systematically. It was found that exchange solvents can significantly affect the chemical and physical properties of prepared Ce-MOFs. Using ethanol as an exchange solvent results in the production of highly crystalline MOF that has the highest surface area (843 m2/g) and pore volume (0.7518 cm3/g) compared to other prepared Ce-MOFs. The dye adsorption experiments revealed that the activated sample by acetone (Ce-MOF-4) exhibited the highest adsorption capacities toward both anionic (270.27 mg/g for Congo Red (CR)) and cationic (227.27 mg/g for Malachite Green (MG)) dyes. This MOF adsorbs both organic dyes via different mechanisms including hydrogen bonding, pore-filling, π-π stacking, coordination, and electrostatic interactions. Moreover, it exhibited good structural stability in acidic solution, neutral solution, and during consecutive adsorption-desorption cycles, confirming its potential to be applied as a stable adsorbent for simultaneous removal of cationic and anionic organic dyes from water.

Simultaneous removal of cationic and anionic dyes by highly efficient and recyclable ZIF-67/expanded vermiculite (ZIF-67/EV) composites

This study focuses on the synthesis of composite materials using Zeolitic imidazolate frameworks (ZIF-67) nanoparticles as an effective adsorbent, along with different concentrations (2-10%) of thermally expanded vermiculite (EV) as a low-cost and natural adsorbent substrate. The pristine materials and their composites were fully characterized using XRD, FTIR, BET, SEM, zeta potential, and EDS techniques. The pseudo-second-order kinetic model described both organic dyes' adsorption on synthesized adsorbents. Accordingly, the calculated adsorption capacities of Congo Red (CR) and Malachite Green (MG) dyes over the synthesized adsorbents were found to be about 22.72 and 49.02 mg/g for pure EV, 100 and 100 mg/g for pure ZIF-67, 90.91 and 100 mg/g for ZIF-67/EV-2, 100 and 100 mg/g for ZIF-67/EV-5, 95.24 and 99.01 mg/g for ZIF-67/EV-7, and 92.59 and 97.09 mg/g for ZIF-67/EV-10, respectively. The Langmuir isotherm model fits experimental isotherm data best in the studied temperature range (298-313 K). Among the synthesized adsorbent materials, the ZIF-67/EV-5 composite (containing 5% EV flakes) showed the highest maximum adsorption capacities of 1428.6 and 1114.2 mg/g for MG and CR dyes at pH 7 and 298 K. Moreover, it showed the highest removal efficiency (up to 99.5%) toward both cationic MG and anionic CR dyes in the binary mixture of both dyes. Finally, the regeneration and recyclability of this composite showed a 12% decrease in dye removal after five adsorption cycles. The synthesized ZIF-67/EV composites may therefore be used as efficient and inexpensive adsorbent materials for the simultaneous removal of cationic and anionic dyes from contaminated water. PRACTITIONER POINTS: ZIF-67/expanded vermiculite composites were synthesized and used to simultaneously remove cationic and anionic dyes from wastewater. Kinetics, isotherms, and thermodynamics of adsorption were studied showing good removal of both dyes. The ZIF-67/EV-5 composite achieved maximum adsorption capacities of 1428.6 and 1114.2 mg/g for cationic Malachite Green and anionic Congo Red dyes, respectively. Various interactions like π-π stacking and coordination are proposed as mechanisms of adsorption. The composite showed good selectivity in separating dyes and maintained high removal efficiency even after 5 reuse cycles.

Dendrite-Free Lithium Batteries Enabled by an Artificial High-Dielectric Biopolymer Interface Layer

Lithium (Li) metal batteries face challenges, such as dendrite growth and electrolyte interface instability. Artificial interface layers alleviate these issues. Here, cellulose nanocrystal (CNC) nanomembranes, with excellent mechanical properties and high specific surface areas, combine with polyvinylidene-hexafluoropropylene (PVDF-HFP) porous membranes to form an artificial solid electrolyte interphase (SEI) layer. The porous structure of PVDF-HFP equalizes the electric field near metallic lithium surfaces. The high mechanical modulus of CNC (6.2 GPa) effectively inhibits dendrite growth, ensures the uniform flow of lithium ions to the lithium metal electrode, and inhibits the growth of lithium dendrites during cycling. The synergy of high polarity β-phase poly(vinylidene fluoride) (PVDF) and CNC provides over 1000 h of stability for Li//Li batteries. Moreover, Li//LiFePO4 (LFP) full cells with this artificial protective layer perform well at 5 C, showcasing the potential of this film in lithium metal batteries.

3D-Printed MOF Monoliths: Fabrication Strategies and Environmental Applications

Metal-organic frameworks (MOFs) have been extensively considered as one of the most promising types of porous and crystalline organic-inorganic materials, thanks to their large specific surface area, high porosity, tailorable structures and compositions, diverse functionalities, and well-controlled pore/size distribution. However, most developed MOFs are in powder forms, which still have some technical challenges, including abrasion, dustiness, low packing densities, clogging, mass/heat transfer limitation, environmental pollution, and mechanical instability during the packing process, that restrict their applicability in industrial applications. Therefore, in recent years, attention has focused on techniques to convert MOF powders into macroscopic materials like beads, membranes, monoliths, gel/sponges, and nanofibers to overcome these challenges.Three-dimensional (3D) printing technology has achieved much interest because it can produce many high-resolution macroscopic frameworks with complex shapes and geometries from digital models. Therefore, this review summarizes the combination of different 3D printing strategies with MOFs and MOF-based materials for fabricating 3D-printed MOF monoliths and their environmental applications, emphasizing water treatment and gas adsorption/separation applications. Herein, the various strategies for the fabrication of 3D-printed MOF monoliths, such as direct ink writing, seed-assisted in-situ growth, coordination replication from solid precursors, matrix incorporation, selective laser sintering, and digital light processing, are described with the relevant examples. Finally, future directions and challenges of 3D-printed MOF monoliths are also presented to better plan future trajectories in the shaping of MOF materials with improved control over the structure, composition, and textural properties of 3D-printed MOF monoliths.

Enhanced sorption and fluorescent detection of bisphenol A by using sodium alginate/cellulose nanofibrils/ZIF-8 composite hydrogel

To address the issue of bisphenol A (BPA) contamination in wastewater, a novel hydrogel, sodium alginate/cellulose nanofibrils/ZIF-8 composite hydrogel (SCZC), was synthesized for efficient BPA removal. The SCZC exhibited an exceptional adsorption capacity of 1696 mg/g, aligning well with both Langmuir and pseudo-second-order models. Furthermore, it exhibited remarkable regeneration properties, maintaining 89.1 % of its adsorption capacity even after undergoing five adsorption-desorption cycles. The synthesized SCZC also acted as a fluorescent sensor for detecting BPA, employing dynamic quenching and offering linear detection ranges of 10-100 mg/L and 0.2-1.0 μg/L, with a low detection limit of 0.06 μg/L. Analysis of adsorption and detection mechanisms revealed that SCZC's exceptional performance could be attributed to the three-dimensional (3D) porous structure formed by sodium alginate and cellulose nanofibrils. Economic analysis indicated that SCZC, in comparison to commercially activated carbon, was relatively inexpensive. This study introduces a novel approach for designing and preparing a sodium alginate-based hydrogel incorporating metal-organic frameworks, offering simultaneous BPA detection and removal capabilities.

Fe3O4/Graphene Oxide/Chitosan Nanocomposite: A Smart Nanosorbent for Lead(II) Ion Removal from Contaminated Water

A new graphene oxide (GO) nanocomposite that contains chitosan, a biological polymer, combined with a magnetic nanoparticle inorganic material (Fe3O4) was successfully prepared and applied for the adsorption of Pb(II) from aqueous solutions. The structural and morphological properties of the GO/Fe3O4/CS (GFC) nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Influent factors for Pb(II) adsorption, including the contacting time, pH of the working medium, working temperature, and adsorbent dosage on the adsorption efficiency, have been optimized. Under optimized conditions, the adsorption isotherm results indicated that the Langmuir model provided a better description for the adsorption of Pb(II) onto the GFC nanosorbent than the Freundlich model. The maximum adsorption capacity (qmax) was 63.45 mg g-1. The pseudo-second-order kinetic model (R2 = 0.999) was fitted with the experimental results, implying that the adsorption of Pb(II) onto GFC is a chemical process. The thermodynamic studies demonstrated the exothermic nature of the adsorption process. Another advantage of the GFC nanosorbent for Pb(II) removal is its capability to be easily recovered under the use of an external magnet and subsequently regenerated. Our work demonstrated that the removal efficiency was stable after several regeneration cycles (i.e., approximately 12% reduction after four successive adsorption-desorption cycles), implying that the GFC nanosorbent exhibits satisfactory regeneration performance. Therefore, with high removal efficiency, high adsorption capacity, and stable reusability, the GFC nanocomposite is a remarkable application potential adsorbent for the in situ treatment of Pb(II) ion-containing aqueous solutions.

Liquid Metal Nanoparticles Physically Hybridized with Cellulose Nanocrystals Initiate and Toughen Hydrogels with Piezoionic Properties

Liquid metal (LM) particles can serve as initiators, functional fillers, and cross-linkers for hydrogels. Herein, we show that cellulose nanocrystals (CNCs) stabilize LM particles in aqueous solutions, such as those used to produce hydrogels. The CNC-coated LM particles initiate free-radical polymerization to form poly(acrylic acid) (PAA) hydrogel with exceptional properties─stretchability ∼2000%, excellent toughness ∼1.8 MJ/m3, mechanical resilience, and efficient self-healing─relative to cross-linked PAA networks polymerized using conventional molecular initiators. FTIR spectroscopy, rheology, and mechanical measurements suggest that physical bonds between PAA and both Ga3+ and LM-CNC particles contribute to the excellent mechanical properties. The gels are used to sense a wide range of strains, such as those associated with human motion, via changes in resistance through the gel. The sensitivity at low strains enables monitoring subtle physiological signals, such as pulse. Without significantly compromising the toughness, soaking the gels in salt solution brings about high ionic conductivity (3.8 S/m), enabling them to detect touch via piezoionic principles; the anions in the gel have higher mobility than cations, resulting in significant charge separation (current ∼30 μA, ∼10 μA/cm2) through the gel in response to touch. These attractive properties are promising for wearable sensors, energy harvesters, and self-powered ionic touch panels.