Advanced MOFs@aerogel composites: Construction and application towards environmental remediation

Scale-up processing of leaf-like zeolitic imidazolate frameworks (ZIF-L)/cellulose for water treatment

Metal-organic frameworks (MOFs) are porous polymeric networks with unique characteristics. Nevertheless, these materials' intrinsic fragility, powdery form, limited processibility, and delicate handling pose significant difficulties for commercial applications. Herein, we reported large-scale production and processing of nanocellulose/leaf-like zeolitic imidazolate framework (ZIF-L), denoted as NanoCelloZIF-L, using Experimental Paper Machine (XPM). Four tanks (volume of 300 L for each tank) with a total volume of 1200 L were used to process the NanoCelloZIF-L sheet with varied weight percentages of the materials 0-30 wt%. The materials were proceeded with and without starch (0.3 wt%) to improve the properties of the final products. The procedure enabled a straightforward, highly efficient method that might be easily implemented for large-scale production of composite materials based on ZIFs. NanoCelloZIF-L sheets were used as an adsorbent to remove water pollutants, including heavy metals and organic dyes. They offered a 90 % adsorption efficiency for organic dyes. They can effectively remove heavy metals for single or mixed metal species, offering adsorption capacities of 460.5 mg/g with high selectivity toward Fe3+ ions.

MOFs-based aerogels and their derivatives for water treatment: A review

Metal-organic frameworks (MOFs) are a class of environmental nano-materials composed of metal ions and organic ligands with remarkable physical and chemical properties, such as huge specific surface area as well as abundant pore volume. Based on their unique structures and properties, MOFs have demonstrated potential applications in the fields of adsorption, gas storage, separation membranes, and catalysis, and have become popular candidates in water treatment technologies. However, MOFs particles in powder form are prone to agglomeration and adhesion effects in water, which leads to problems such as difficult separation and secondary pollution. As an ideal carrier for MOFs, aerogels exhibit a unique three-dimensional interconnected pore structure, which endows aerogels with high porosity properties and excellent adsorption capacity. Researchers have skillfully combined MOFs with aerogels to create a new type of MOF aerogel composites (MOFACs). These composites are converted into highly porous and high-strength carbon aerogels through a high-temperature pyrolysis process in an inert environment. These carbon aerogels not only retain the high catalytic efficiency of MOFs, but also inherit the advantages of aerogels in terms of light weight, low density and easy handling. This paper reviews various types of MOFACs, each of which possesses different chemical compositions and physical properties, thus adapting to different applications. The paper also discusses the applications of MOFACs and carbon aerogels in water treatment for catalysis, selective adsorption and solid phase microextraction.

Enhanced capacity in cellulose aerogel for carbon dioxide capture through modified by metal-organic framework

Microporous metal-organic frameworks (MOF) exhibit excellent carbon dioxide (CO2) adsorption performance and selectivity for CO2/N2 separation. However, the challenges associate with the recycling and reuse of MOF powders hinder their practical applications. To address these limitations, a flexible and stable MOF-based composite material was designed by immobilizing UiO-66(Zr)-(OH)2 onto cellulose nanofibers (CNFs) aerogels (MOF-CNFs), which featured high porosity. Experimental results showed that MOF-CNFs exhibited sensitivity to CO2 adsorption at low pressure and achieved a CO2 adsorption capacity of 1.8 mmol/g at 0.15 bar under the 298 K. This represented an 8.8 % improvement compared to the MOF. Ideal adsorbed solution theory (IAST) calculations indicated selectivity for CO2/N2 mixtures (molar ratio 15:85) as high as 66. After eight adsorption-desorption cycles, the CO2 adsorption capacity retained 97 % of its initial value. These results highlighted the significant potential of MOF-CNFs as reusable and highly efficient CO2 separation adsorbents for practical applications, such as flue gas capture.

MIL-100-Fe self-assembled cellulose nanofibers sponge for Diclofenac cascade encapsulation

The conventional hydrothermal synthesis and inherent hysteresis behavior limited the application of MOFs owing to the low kinetic efficiency in dynamic molecular adsorption. Herein, we developed an in-situ nucleation strategy for the preparation of MIL-100-Fe and immobilized it with hierarchy porous scaffold of TEMPO oxidized cellulose nanofiber (TCNF) sponge in the absence of additional organic solvent during fabrication under ambient conditions. The newly recognized mechanisms of gradient molecular transfer were proposed to illustrate the comprehensive DCF adsorption process from solution to micropores of MIL-100-Fe at molecule level triggered by the stray capacitance, varied Laplace pressure, size exclusion and cellulosic labyrinth. Additionally, the superior biocompatibility and natural degradability (in 24 h) of MIL@TCNF sponge were demonstrated. The used material could be converted rapidly to zero-valent iron (ZVI) sponge via simple reduction process, achieving both dehalogenation of Diclofenac (DCF) and material regeneration. These findings uncover the propagable mechanisms of molecular-diffusion driven adsorption cascade and provide a novel fabrication strategy of 3-D environmental functional sponge with reusability and biodegradability for water pollution control.

Covalently Bound MOF/COF Aerogels as Robust Catalytic Filters for Rapid Nerve Agent Decomposition

Metal-organic frameworks (MOFs) show promising results in various fields, such as gas separation and catalysis, but they face limitations due to problems associated with their low processability. This study addresses these challenges by utilizing postsynthetic modification (PSM) of NH2-UiO-66 and NH2-MOF-808 with 1,3,5-benzene tricarbaldehyde (BTCA) to form hybrid aerogels consisting of MOF-loaded covalent organic framework (COF). BTCA-modified MOF nanoparticles via imine bond formation were confirmed by 1H NMR, FTIR, and solid-state 13C NMR spectroscopies. MOF/COF composites were analyzed via TGA, PXRD, BET, and solid-state 13C NMR, showing retained crystallinity and increased porosity in comparison to the sum of the individual components. Moreover, improved aerogel mechanical properties and increased MOF loading of up to 75 wt % were achieved for covalently bound aerogels. Hybrid aerogel composites were successfully utilized as catalytic filters for the decomposition of nerve agent simulant and pesticide dimethyl-4-nitrophenylphosphate (DMNP), avoiding secondary pollution associated with MOF powder catalysis.

Environmental applications of metal-organic framework-based three-dimensional macrostructures: a review

Metal-organic frameworks (MOFs) hold considerable promise for environmental remediation owing to their exceptional performance and distinctive structure. Nonetheless, the practical implementation of MOFs encounters persistent technical hurdles, notably susceptibility to loss, challenging recovery, and potential environmental toxicity arising from the fragility, insolubility, and poor processability of MOFs. MOF-based three-dimensional macrostructures (3DMs) inherit the advantageous attributes of the original MOFs, such as ultra-high specific surface area, tunable pore size, and customizable structure, while also incorporating the intriguing characteristics of bulk materials, including hierarchical structure, facile manipulation, and structural flexibility. Consequently, they exhibit rapid mass transfer and exceptional practicality, offering extensive potential applications in environmental remediation. This review presents a comprehensive overview of recent advancements in utilizing MOF-based 3DMs for environmental remediation, encompassing their fascinating characteristics, preparation strategies, and characterization methods, and highlighting their exceptional performance in pollutant adsorption, catalysis, and detection. Furthermore, existing challenges and prospects are presented to advance the utilization of MOF-based materials across various domains, particularly in environmental remediation.

MOFs-derived porous carbon embedded Fe0 nanoparticles as peroxymonosulfate activator for efficient degradation of organic pollutants

Achieving the harmless degradation of organic pollutants remains a challenging task for the advanced oxidation processes. Metal-organic frameworks have emerged in the field of energy and environmental catalysis. Herein, MIL-101(Fe) was employed as the precursor to prepare a porous carbon embedded Fe0 nanoparticles (Fe0@C) via a pyrolytic process under N2 protection. MIL-101(Fe) and Fe0@C were characterized in detail by various instrumental techniques. The control experiments indicated that Fe0@C exhibited much higher capacity to activate peroxymonosulfate (PMS) for the degradation of Levofloxacin (LEV) than MIL-101(Fe). Within 60 min reaction time, LEV degradation efficiency was increased from 37.0% in the MIL-101(Fe)/PMS system to 96.3% in the Fe0@C/PMS one. The affecting parameters of Fe0@C/PMS system were investigated systematically, including LEV concentration, Fe0@C dosage, PMS dosage, solution pH and coexisting anions. Furthermore, various representative organic pollutants could be efficiently degraded in the Fe0@C/PMS system. Radical quenching tests and electron paramagnetic resonance (EPR) disclosed that singlet oxygen (1O2), sulfate radical (SO4•-) and hydroxyl radical (•OH) governed the degradation of LEV, among which 1O2 played the most prominent role. Meanwhile, the degradation intermediates and pathways of LEV under the radical and non-radical attacks were deduced by high-performance liquid chromatography-quadrupole-time of flight mass spectrometry (HPLC-QTOF/MS) assisted by density functional theory (DFT) calculations. The reasonably designed Fe0@C might facilitate electron transfer and thus promote Fe(III)/Fe(II) cycle and PMS activation. This work will provide a new idea for the development of MOFs-derived carbon-based persulfate activators.

Green Fabrication of Zinc-Based Metal-Organic Frameworks@Bacterial Cellulose Aerogels via In Situ Mineralization for Wastewater Treatment

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.

Solution Processable Metal-Organic Frameworks: Synthesis Strategy and Applications

Metal-organic frameworks (MOFs), constructed by inorganic secondary building units with organic linkers via reticular chemistry, inherently suffer from poor solution processability due to their insoluble nature, resulting from their extensive crystalline networks and structural rigidity. The ubiquitous occurrence of precipitation and agglomeration of MOFs upon formation poses a significant obstacle to the scale-up production of MOF-based monolith, aerogels, membranes, and electronic devices, thus restricting their practical applications in various scenarios. To address the previously mentioned challenge, significant strides have been achieved over the past decade in the development of various strategies aimed at preparing solution-processable MOF systems. In this review, the latest advance in the synthetic strategies for the construction of solution-processable MOFs, including direct dispersion in ionic liquids, surface modification, controllable calcination, and bottom-up synthesis, is comprehensively summarized. The respective advantages and disadvantages of each method are discussed. Additionally, the intriguing applications of solution-processable MOF systems in the fields of liquid adsorbent, molecular capture, sensing, and separation are systematically discussed. Finally, the challenges and opportunities about the continued advancement of solution-processable MOFs and their potential applications are outlooked.

Metal-Organic Framework and Covalent-Organic Framework-Based Aerogels: Synthesis, Functionality, and Applications

Metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs)-based aerogels are garnering significant attention owing to their unique chemical and structural properties. These materials harmoniously combine the advantages of MOFs and COFs-such as high surface area, customizable porosity, and varied chemical functionality-with the lightweight and structured porosity characteristic of aerogels. This combination opens up new avenues for advanced applications in fields where material efficiency and enhanced functionality are critical. This review provides a comparative overview of the synthetic strategies utilized to produce pristine MOF/COF aerogels as well as MOF/COF-based hybrid aerogels, which are functionalized with molecular precursors and nanoscale materials. The versatility of these aerogels positions them as promising candidates for addressing complex challenges in environmental remediation, energy storage and conversion, sustainable water-energy technologies, and chemical separations. Furthermore, this study discusses the current challenges and future prospects related to the synthesis techniques and applications of MOF/COF aerogels.

Aerogels based on Bacterial Nanocellulose and their Applications

Microbial cellulose stands out for its exceptional characteristics in the form of biofilms formed by highly interlocked fibrils, namely, bacterial nanocellulose (BNC). Concurrently, bio-based aerogels are finding uses in innovative materials owing to their lightweight, high surface area, physical, mechanical, and thermal properties. In particular, bio-based aerogels based on BNC offer significant opportunities as alternatives to synthetic or mineral counterparts. BNC aerogels are proposed for diverse applications, ranging from sensors to medical devices, as well as thermal and electroactive systems. Due to the fibrous nanostructure of BNC and the micro-porosity of BNC aerogels, these materials enable the creation of tailored and specialized designs. Herein, a comprehensive review of BNC-based aerogels, their attributes, hierarchical, and multiscale features are provided. Their potential across various disciplines is highlighted, emphasizing their biocompatibility and suitability for physical and chemical modification. BNC aerogels are shown as feasible options to advance material science and foster sustainable solutions through biotechnology.

Spherical cellulose/chitosan aerogel-supported MOF-199 for the magnetic solid-phase extraction of benzodiazepines from urine

Metal-organic frameworks (MOFs) are promising materials for sample pretreatment. The performance improvement of powdered MOFs is hindered by their aggregation and difficult recovery. To overcome these issues, a biodegradable lightweight spherical aerogel was used as a support for the in situ growth of copper-based MOFs (MOF-199). Furthermore, Fe3O4 nanoparticles were incorporated into the aerogel to achieve magnetic properties. Thus, hybrid aerogel spheres containing MOF-199 supported on magnetic oxidized cellulose nanofiber/carboxymethyl chitosan (MOF-199@mag-CNF/CMC) were fabricated. The effects of Fe3O4 loading amount and organic-ligand concentration on the properties (spherical geometry and mechanical strength) of the hybrid aerogel spheres were studied. Their potential application in the extraction of benzodiazepines (BZPs) from urine samples prior to liquid chromatography-mass spectrometry was evaluated. The highly dispersed MOF-199 crystals on the spherical aerogel effectively overcame the inherent structural shrinkage of the bare aerogel spheres; thus, the MOF-199@mag-CNF/CMC aerogel spheres were robust and could withstand repeated use for at least eight consecutive extraction cycles. Further, MOF-199@mag-CNF/CMC exhibited improved BZP extraction efficiency, which was 2.5-11.6 times higher than that of bare Cu2+@mag-CNF/CMC aerogel spheres, primarily due to additional π-π interaction and H-bonding as well as improved specific surface area. Parameters influencing the extraction and desorption processes were also comprehensively investigated. Under optimal conditions, this method provided a wide linear range of 0.1-10 µg/L (R2 > 0.995) and good precision (2.8-6.7% for intra-day; 1.9-7.8 % for inter-day). The limits of detection and quantification ranged from 0.02 to 0.11 µg/L and from 0.06 to 0.33 µg/L, respectively. The recoveries for the urine samples spiked with three concentrations of BZPs ranged from 73.9 % to 114.1 %. The proposed method is simple, sensitive and eco-friendly and can be used for the determination of BZPs from urine for clinical and forensic examinations.

Recent Progress in MOF-Aerogel Fabrication and Applications

Recent advancements in metal-organic frameworks (MOFs) underscore their significant potential in chemical and materials research, owing to their remarkable properties and diverse structures. Despite challenges like intrinsic brittleness, powdered crystalline nature, and limited stability impeding direct applications, MOF-based aerogels have shown superior performance in various areas, particularly in water treatment and contaminant removal. This review highlights the latest progress in MOF-based aerogels, with a focus on hybrid systems incorporating materials like graphene, carbon nanotube, silica, and cellulose in MOF aerogels, which enhance their functional properties. The manifold advantages of MOF-based aerogels in energy storage, adsorption, and catalysis are discussed, with an emphasizing on their improved stability, processability, and ease of handling. This review aims to unlock the potential of MOF-based aerogels and their real-world applications. Aerogels are expected to reshape the technological landscape of MOFs through enhanced stability, adaptability, and efficiency.

Boosted visible-light-induced photo-Fenton degradation of organic pollutants over a novel direct Z-scheme NH2-MIL-125(Ti)@FeOCl heterojunction catalyst

Improving the charge separation, charge transfer, and effective utilization is crucial in a photocatalysis system. Herein, we prepared a novel direct Z-scheme NH2-MIL-125(Ti)@FeOCl (Ti-MOF@FeOCl) composite photocatalyst through a simple method. The prepared composite catalyst was utilized in the photo-Fenton degradation of Rhodamine B (RhB) and ciprofloxacin (CIP). The Ti-MOF@FeOCl (10FeTi-MOF) catalyst exhibited the highest catalytic performance and degraded 99.1 and 66% of RhB and CIP, respectively. However, the pure NH2-MIL-125(Ti) (Ti-MOF) and FeOCl catalysts achieved only 50 and 92% of RhB and 50 and 37% of CIP, respectively. The higher catalytic activities of the Ti-MOF@FeOCl composite catalyst could be due to the electronic structure improvements, photoinduced charge separations, and charge transfer abilities in the catalyst system. The composite catalysts have also enhanced adsorption and visible light-responsive properties, allowing for efficient degradation. Furthermore, the electron paramagnetic resonance (EPR) signals, the reactive species trapping experiments, and Mott-Schottky (M - S) measurements revealed that the photogenerated superoxide radical (•O2-), hydroxyl radical (•OH), and holes (h+) played a vital role in the degradation process. The results also demonstrated that the Ti-MOF@FeOCl heterojunction composite catalysts could be a promising photo-Fenton catalyst system for the environmental remediation. Environmental implications The discharging of toxic contaminants such as organic dyes, antibiotics, and other emerging pollutants to the environment deteriorates the ecosystem. Specifically, the residues of organic pollutants recognized as a threat to ecosystem and a cause for carcinogenic effects. Among them, ciprofloxacin is one of antibiotics which has biological resistance, and metabolize partially in the human or animal bodies. It is also difficult to degrade ciprofloxacin completely with traditional treatment methods. Similarly, organic dyes are also toxic and a cause for carcinogenic effects. Therefore, effective degradation of organic pollutants such as RhB and ciprofloxacin with appropriate method is crucial.

A comprehensive review on preparation and functional application of the wood aerogel with natural cellulose framework

As the traditional aerogel has defects such as poor mechanical properties, complicated preparation process, high energy consumption and non-renewable, wood aerogel as a new generation of aerogel shows unique advantages. With a natural cellulose framework, wood aerogel is a novel nano-porous material exhibiting exceptional properties such as light weight, high porosity, large specific surface area, and low thermal conductivity. Furthermore, its adaptability to further functionalization enables versatile applications across diverse fields. Driven by the imperative for sustainable development, wood aerogel as a renewable and eco-friendly material, has garnered significant attention from researchers. This review introduces preparation methods of wood aerogel based on the top-down strategy and analyzes the factors influencing their key properties intending to obtain wood aerogels with desirable properties. Avenues for realizing its functionality are also explored, and research progress across various domains are surveyed, including oil-water separation, conductivity and energy storage, as well as photothermal conversion. Finally, potential challenges associated with wood aerogel exploitation and utilization are addressed, alongside discussions on future prospects and research directions. The results emphasize the broad research value and future prospects of wood aerogels, which are poised to drive high-value utilization of wood and foster the development of green multifunctional aerogels.

An Efficient and Economic Approach for Producing Nanocellulose-Based Aerogel from Kapok Fiber

Cellulose nanofibers (NF) were extracted from kapok fibers using TEMPO oxidation, followed by a combination of mechanical grinding and ultrasonic processing. The TEMPO-mediated oxidation significantly impacted the mechanical disintegration behavior of the kapok fibers, resulting in a high NF yield of 98%. This strategy not only improved the fibrillation efficiency but also reduced overall energy consumption during NF preparation. An ultralight and highly porous NF-based aerogel was successfully prepared using a simple ice-templating technique. It had a low density in the range of 3.5-11.2 mg cm-3, high compressional strength (160 kPa), and excellent thermal insulation performance (0.024 W m-1 K-1). After silane modification, the aerogel displayed an ultralow density of 7.9 mg cm-3, good hydrophobicity with a water contact angle of 128°, and excellent mechanical compressibility with a high recovery of 92% at 50% strain. Benefiting from the silene support structure, it showed a high oil absorptive capacity (up to 71.4 g/g for vacuum pump oil) and a remarkable oil recovery efficiency of 93% after being reused for 10 cycles. These results demonstrate that our strategy endows nanocellulose-based aerogels with rapid shape recovery and high liquid absorption capabilities.

Wearable Aerogels for Personal Thermal Management and Smart Devices

Extreme climates have become frequent nowadays, causing increased heat stress in human daily life. Personal thermal management (PTM), a technology that controls the human body's microenvironment, has become a promising strategy to address heat stress. While effective in ordinary environments, traditional high-performance fibers, such as ultrafine, porous, highly thermally conductive, and phase change materials, fall short when dealing with harsh conditions or large temperature fluctuations. Aerogels, a third-generation superinsulation material, have garnered extensive attention among researchers for their thermal management applications in building energy conservation, transportation, and aerospace, attributed to their extremely low densities and thermal conductivity. While aerogels have historically faced challenges related to weak mechanical strength and limited secondary processing capacity, recent advancements have witnessed notable progress in the development of wearable aerogels for PTM. This progress underscores their potential applications within extremely harsh environments, serving as self-powered smart devices and sensors. This Review offers a timely overview of wearable aerogels and their PTM applications with a particular focus on their wearability and suitability. Finally, the discussion classifies five types of PTM applications based on aerogel function: thermal insulation, heating, cooling, adaptive regulation (involving thermal insulation, heating, and cooling), and utilization of aerogels as wearable smart devices.

Design and Advanced Manufacturing of NU-1000 Metal-Organic Frameworks with Future Perspectives for Environmental and Renewable Energy Applications

Metal-organic frameworks (MOFs) represent a relatively new family of materials that attract lots of attention thanks to their unique features such as hierarchical porosity, active metal centers, versatility of linkers/metal nodes, and large surface area. Among the extended list of MOFs, Zr-based-MOFs demonstrate comparably superior chemical and thermal stabilities, making them ideal candidates for energy and environmental applications. As a Zr-MOF, NU-1000 is first synthesized at Northwestern University. A comprehensive review of various approaches to the synthesis of NU-1000 MOFs for obtaining unique surface properties (e.g., diverse surface morphologies, large surface area, and particular pore size distribution) and their applications in the catalysis (electro-, and photo-catalysis), CO2 reduction, batteries, hydrogen storage, gas storage/separation, and other environmental fields are presented. The review further outlines the current challenges in the development of NU-1000 MOFs and their derivatives in practical applications, revealing areas for future investigation.

An Updated Overview of Magnetic Composites for Water Decontamination

Water contamination by harmful organic and inorganic compounds seriously burdens human health and aquatic life. A series of conventional water purification methods can be employed, yet they come with certain disadvantages, including resulting sludge or solid waste, incomplete treatment process, and high costs. To overcome these limitations, attention has been drawn to nanotechnology for fabricating better-performing adsorbents for contaminant removal. In particular, magnetic nanostructures hold promise for water decontamination applications, benefiting from easy removal from aqueous solutions. In this respect, numerous researchers worldwide have reported incorporating magnetic particles into many composite materials. Therefore, this review aims to present the newest advancements in the field of magnetic composites for water decontamination, describing the appealing properties of a series of base materials and including the results of the most recent studies. In more detail, carbon-, polymer-, hydrogel-, aerogel-, silica-, clay-, biochar-, metal-organic framework-, and covalent organic framework-based magnetic composites are overviewed, which have displayed promising adsorption capacity for industrial pollutants.

In Situ Growth of MOF from Wood Aerogel toward Bromide Ion Adsorption in Simulated Saline Water

Utilizing metal-organic framework (MOF) materials for the extraction of bromide ions (Br-) from aqueous solutions, as an alternative to chlorine gas oxidation technology, holds promising potential for future applications. However, the limitations of powdered MOFs, such as low utilization efficiency, ease of aggregation in water, and challenging recovery processes, have hindered their practical application. Shaping MOF materials into application-oriented forms represents an effective but challenging approach to address these drawbacks. In this work, a novel Ag-UiO-66-(OH)2@delignified wood cellulose aerogel (CA) adsorbent is synthesized using an oil bath impregnation method, involving the deposition of UiO-66-(OH)2 nanoparticles onto CA and the uniform dispersion of Ag0 nanoparticles across its surface. CA, characterized by the intertwined cellulose nanofiber structure and a highly hydrophilic surface, serves as an ideal substrate for the uniform growth of UiO-66-(OH)2 nanoparticles, which, in turn, spontaneously reduce Ag+ to form distributed Ag0 nanoparticles due to the abundant hydroxyl groups provided. Leveraging the well-defined biological structure of CA, which offers excellent mass transfer channels, and the highly dispersed Ag adsorption sites, Ag-UiO-(OH)2/CA exhibits remarkable adsorption capacity (642 mg/gAg) under optimized conditions. Furthermore, an integrated device is constructed by interconnecting Ag-UiO-(OH)2/CA adsorbents in series, affirming its potential application in the continuous recovery of Br-. This study not only presents an efficient Ag-UiO-(OH)2/CA adsorbent for Br- recovery but also sheds light on the extraction of other valuable elements from various liquid ores.

An Updated Overview of Silica Aerogel-Based Nanomaterials

Silica aerogels have gained much interest due to their unique properties, such as being the lightest solid material, having small pore sizes, high porosity, and ultralow thermal conductivity. Also, the advancements in synthesis methods have enabled the creation of silica aerogel-based composites in combination with different materials, for example, polymers, metals, and carbon-based structures. These new silica-based materials combine the properties of silica with the other materials to create a new and reinforced architecture with significantly valuable uses in different fields. Therefore, the importance of silica aerogels has been emphasized by presenting their properties, synthesis process, composites, and numerous applications, offering an updated background for further research in this interdisciplinary domain.

Recent advances in metal organic frameworks-based magnetic nanomaterials for waste water treatment

Magnetic nanoparticle-incorporated metal organic frameworks (MOF) are potential composites for various applications such as catalysis, water treatment, drug delivery, gas storage, chemical sensing, and heavy metal ion removal. MOFs exhibits high porosity and flexibility enabling guest species like heavy metal ions to diffuse into bulk structure. Additionally, shape and size of the pores contribute to selectivity of the guest materials. Incorporation of magnetic materials allows easy collection of adsorbent materials from solution system making the process simple and cost-effective. In view of the above advantages in the present review article, we are discussing recent advances of different magnetic material-incorporated MOF (Mg-MOF) composite for application in photocatalytic degradation of dyes and toxic chemicals, adsorption of organic compounds, adsorption of heavy metal ions, and adsorption of dyes. The review initially discusses on properties of Mg-MOF, different synthesis techniques such as mechanochemical, sonochemical (ultrasound) synthesis, slow evaporation and diffusion methods, solvo(hydro)-thermal and iono-thermal method, microwave-assisted method, microemulsion method post-synthetic modification template strategies and followed by application in waste water treatment.

Synthesis and fabrication of segregative and durable MnO2@chitosan composite aerogel beads for uranium(VI) removal from wastewater

To address the imperative need for efficient removal of uranium-containing wastewater and mitigate radioactive contamination risks associated with nuclear energy, the development of materials with high removal efficiency and facile separation is crucial. This study designed and synthesised MnO2@chitosan (CTS) composite aerogel beads by in-situ growing δ-MnO2 on porous CTS aerogel beads. This approach not only mitigates the agglomeration of MnO2 nanospheres but also significantly enhances the porous structure and surface area of MnO2@CTS. These cost-effective and eco-friendly millimeter-scale spherical aerogels exhibited convenient separation properties after adsorption. These characteristics help mitigate the risk of equipment seam blockage and secondary pollution that are often associated with powdered adsorbents. Additionally, MnO2@CTS exhibited remarkable mechanical strength (stress approximately 0.55 MPa at 60 % strain), enabling rapid separation and easy regeneration while maintaining high adsorption performance even after five cycles. Significantly, MnO2@CTS exhibited a maximum adsorption capacity of 410.7 mg/g at pH 6 and 298 K, surpassing reported values for most CTS/MnO2-based adsorbents. The chemisorption process of U(VI) on MnO2@CTS followed the pseudo-second-order kinetic and Dubinin-Radushkevish models. X-ray photoelectron spectroscopy analysis further confirmed the reduction of U(VI) to U(V/IV). These findings highlight the substantial potential of MnO2@CTS aerogel beads for U(VI) removal from aqueous solutions, positioning them as a promising solution for addressing U(VI) contamination in wastewater.

Review: Synthesis of metal organic framework-based composites for application as immunosensors in food safety

Ensuring food safety continues to be one of the major global challenges. For effective food safety monitoring, fast, sensitive, portable, and efficient food safety detection strategies must be devised. Metal organic frameworks (MOFs) are porous crystalline materials that have attracted attention for use in high-performance sensors for food safety detection owing to their advantages such as high porosity, large specific surface area, adjustable structure, and easy surface functional modification. Immunoassay strategies based on antigen-antibody specific binding are one of the important means for accurate and rapid detection of trace contaminants in food. Emerging MOFs and their composites with excellent properties are being synthesized, providing new ideas for immunoassays. This article summarizes the synthesis strategies of MOFs and MOF-based composites and their applications in the immunoassays of food contaminants. The challenges and prospects of the preparation and immunoassay applications of MOF-based composites are also presented. The findings of this study will contribute to the development and application of novel MOF-based composites with excellent properties and provide insights into advanced and efficient strategies for developing immunoassays.

Metal-organic frameworks (MOFs) based luminescent and electrochemical sensors for food contaminant detection

With the increasing population, food toxicity has become a prevalent concern due to the growing contaminants of food products. Therefore, the need for new materials for toxicant detection and food quality monitoring will always be in demand. Metal-organic frameworks (MOFs) based on luminescence and electrochemical sensors with tunable porosity and active surface area are promising materials for food contaminants monitoring. This review summarizes and studies the most recent progress on MOF sensors for detecting food contaminants such as pesticides, antibiotics, toxins, biomolecules, and ionic species. First, with the introduction of MOFs, food contaminants and materials for toxicants detection are discussed. Then the insights into the MOFs as emerging materials for sensing applications with luminescent and electrochemical properties, signal changes, and sensing mechanisms are discussed. Next, recent advances in luminescent and electrochemical MOFs food sensors and their sensitivity, selectivity, and capacities for common food toxicants are summarized. Further, the challenges and outlooks are discussed for providing a new pathway for MOF food contaminant detection tools. Overall, a timely source of information on advanced MOF materials provides materials for next-generation food sensors.

The removal enhancement of organic contaminations and optimization of the photocatalytic efficiency by Box-Behnken design using ZnO-TiO2/porous graphene aerogel

In this study, zinc oxide-titanium dioxide/graphene aerogel (ZnO-TiO2/GA) was successfully synthesized through a simple and cost-effective hydrothermal self-assembly process. Besides, the surface response model and the experimental design according to the Box-Behnken model were selected to determine the optimal removal efficiency for crystal violet (CV) dye and para-nitrophenol (p-NP) phenolic compound. According to the obtained results, the highest degradation efficiency for CV dye of 99.6% was obtained under the following conditions: pH 6.7, CV concentration of 23.0 mg/L, and catalyst dose of 0.30 g/L. For p-NP, the degradation efficiency reached 99.1% under the following conditions: H2O2 volume of 1.25 mL, pH 6.8, and catalyst dose of 0.35 g/L. Therewithal, kinetic models of adsorption-photodegradation, thermodynamic adsorption, and free radical scavenging experiments were also investigated to propose the specific mechanisms involving the removal of CV dye and p-NP. According to the aforementioned results, the study provided a resulting ternary nanocomposite with great removal performance for water pollutants via the synergetic effects of adsorption and photodegradation processes.

Research progress of applications for nano-materials in improved QuEChERS method

The quick, easy, cheap, effective, rugged, and safe (QuEChERS) approach is widely used in sample pretreatment in agricultural products, food, environment, etc. And nano-materials are widely used in QuEChERS method due to its small size and large specific surface area. In this review, we examine the typical applications of several commonly used nano-materials in improved QuEChERS method. These materials include multi-walled carbon nanotubes (MWCNTs) and their derivatives, magnetic nanoparticles (MNPs), metal organic frameworks (MOFs), covalent organic frameworks (COFs), graphene oxide (GO), lipid and protein adsorbent (LPAS), cucurbituril (CBs), and carbon nano-cages (CNCs), and so on. The strengths and weaknesses of each nano-material are presented, as well as the challenging aspects that need to be addressed in future research. By comparing the applications and the current technology development, this review suggests utilizing artificial intelligence (AI) to screen suitable combinations of purification agents and performing virtual simulation experiments to verify the reliability of this methodology. By doing so, we aim to accelerate the development of new products and decrease the cost of innovation. It also recommends designing smarter pretreatment instruments to enhance the convenience and automation of the sample pretreatment process and reduce the margin for human error.

Turning precious metal-loaded e-waste to useful catalysts: Investigation into supercilious recovery and catalyst viability for peroxymonosulfate activation

Here, the key tasks to be accomplished are selective precious metal recovery from e-wastewater and their conversion into valuable catalysts for peroxymonosulfate (PMS) activation. In this regard, we developed a hybrid material using 3D functional graphene foam and copper para-phenylenedithol (Cu-pPDT) MOF. The prepared hybrid showed a supercilious recovery of 92-95% even up to five cycles for Au(III) and Pd(II), which can be viewed as a reference for both the 2D graphene and the MOFs family. The outstanding performance has been attributed principally to the impact of diverse functionality as well as the unique morphology of 3D graphene foam, which provided a wide range of surface area and additional active sites in the hybrid frameworks. To prepare the surface-loaded metal nanoparticle catalysts, the sorbed samples recovered after precious metal extraction were calcined at 800 °C. The viability of the developed catalysts for the breakdown of 4-nitrophenol (4-NP) via PMS activation was investigated. Electron paramagnetic resonance spectroscopy (EPR) and experiments with radical scavengers suggest that sulfate and hydroxyl radicals are the main reactive species involved in the breakdown of 4-NP. This is because the active graphitic carbon matrix and the exposed precious metal and copper active sites work together in a way that is more effective.

Photodynamic activity enhanced by in situ biosynthetic BC/CQDs@PCN-224 membranes through FRET strategy

Porphyrin-based metal organic frameworks (MOFs) with efficient bactericidal performance have increasingly attracted attention in photodynamic inactivation materials. However, low reactive oxygen species (ROS) yield and drug residue hazards of current porphyrin-MOFs materials lead to unsatisfactory clinical therapeutic effects. In this paper, carbon quantum dots (CQDs) were encapsulated into PCN-224, which enhanced the photodynamic activity of the MOFs through fluorescence resonance energy transfer (FRET) process. Singlet oxygen (¹O₂) detection confirmed that the photodynamic activity of CQDs-doped PCN-224 (CQDs@PCN-224) was enhanced than that of pristine PCN-224 under illumination. Furthermore, the CQDs@PCN-224 were firmly embedded into bacterial cellulose (BC) nanofibrous membranes by using an eco-friendly biosynthetic approach, efficiently preventing MOFs leakage during use. The results of bactericidal assays demonstrated that BC/CQDs@PCN-224 membrane with higher photodynamic activity causes more severe disruption to bacterial structure and possesses better antibacterial efficiency (>99.99 % reduction of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli O157:H7 within 30 min) than BC/PCN-224 membrane under visible light illumination (500 W, 15 cm height, λ ≥ 420 nm). In addition, the biosynthesized BC/CQDs@PCN-224 membrane showed good hemocompatibility and low cytotoxicity, revealing that the BC- and MOFs-based material with enhanced PDI efficiency and satisfying safety has great potential in medical fields.

Bimetallic MOFs loaded cellulose as an environment friendly bioadsorbent for highly efficient tetracycline removal

Due to the increasingly serious antibiotic-related pollution, it is crucial to develop novel green bioadsorbents to effectively remove antibiotics from aqueous solutions. In this study, Fe doped zeolitic imidazolate frameworks-8 loaded cellulose (Fe/ZIF-8@cellulose) aerogels were prepared. The synthesized Fe/ZIF-8@cellulose aerogels were characterized experimentally including morphology observation and chemical compositions determination. The effects of bioadsorbent dosage, solution pH, adsorption time, initial TC concentration and adsorption temperature on the TC adsorption behaviors were systematically studied. Due to the introduction of Fe in the ZIF-8, the maximum adsorption capacity of Fe/ZIF-8@cellulose for TC could reach as high as 1359.2 mg/g, which is higher than the reported ZIF-8 loaded polysaccharide based adsorbents. The adsorption kinetics and isotherm of TC adsorption were also determined. With the cellulose as the matrix to load Fe/ZIF-8, the obtained Fe/ZIF-8@cellulose aerogels exhibited good reusability. Most importantly, the TC adsorption mechanism was proposed. The results of our finding suggest that the Fe doping into MOFs is an effective strategy to improve the antibiotics adsorption performance and the application of cellulose as the matrix is a valuable method to increase the cyclic utilization. This study highlights the potentials of applying the Fe/ZIF-8@cellulose aerogels in the antibiotics removal for practical wastewater.

A comprehensive review of hydrophobic silica and composite aerogels: synthesis, properties and recent progress towards environmental remediation and biomedical applications

The hydrophobicity of silica and composite aerogels has enabled them to acquire applications in a variety of fields. With remarkable structural, morphological, and physiochemical properties such as high porosity, surface area, chemical stability, and selectivity, these materials have gained much attention of researchers worldwide. Moreover, the hydrophobic conduct has enabled these aerogels to adsorb substances, i.e., organic pollutants, without collapsing the pore and network structure. Hence, considering such phenomenal properties and great adsorption potential, exploiting these materials for environmental and biomedical applications is trending. The present study explores the most recent advances in synthetic approaches and resulting properties of hydrophobic silica and composite aerogels. It presents the various precursors and co-precursors used for hydrophobization and gives a comparative analysis of drying methods. Moreover, as a major focus, the work presents the recent progress where these materials have shown promising results for various environmental remediation and biomedical applications. Finally, the bottlenecks in synthesis and applicability along with future prospects are given in conclusions.