Catalytic MOF-loaded cellulose sponge for rapid degradation of chemical warfare agents simulant

Immobilized Urease Vector System Based on the Dynamic Defect Regeneration Strategy for Efficient Urea Removal

The clearance of urea poses a formidable challenge, and its excessive accumulation can cause various renal diseases. Urease demonstrates remarkable efficacy in eliminating urea, but cannot be reused. This study aimed to develop a composite vector system comprising microcrystalline cellulose (MCC) immobilized with urease and metal-organic framework (MOF) UiO-66-NH2, denoted as MCC@UiO/U, through the dynamic defect generation strategy. By utilizing competitive coordination, effective immobilization of urease into MCC@UiO was achieved for efficient urea removal. Within 2 h, the urea removal efficiency could reach up to 1500 mg/g, surpassing an 80% clearance rate. Furthermore, an 80% clearance rate can also be attained in peritoneal dialyzate from patients. MCC@UiO/U also exhibits an exceptional bioactivity even after undergoing 5 cycles of perfusion, demonstrating remarkable stability and biocompatibility. This innovative approach and methodology provide a novel avenue and a wide range of immobilized enzyme vectors for clinical urea removal and treatment of kidney diseases, presenting immense potential for future clinical applications.

Research Progress in the Degradation of Chemical Warfare Agent Simulants Using Metal-Organic Frameworks

Chemical warfare agents primarily comprise organophosphorus nerve agents, saliva alkaloids, cyanides, and mustard gas. Exposure to these agents can result in severe respiratory effects, including spasms, edema, and increased secretions leading to breathing difficulties and suffocation. Protecting public safety and national security from such threats has become an urgent priority. Porous metal-organic framework (MOF) materials have emerged as promising candidates for the degradation of chemical warfare agents due to their large surface area, tunable pore size distribution, and excellent catalytic performance. Furthermore, combining MOFs with polymers can enhance their elasticity and processability and improve their degradation performance. In this review, we summarize the literature of the past five years on MOF-based composite materials and their effectiveness in degrading chemical warfare agents. Moreover, we discuss key factors influencing their degradation efficiency, such as MOF structure, pore size, and functionalization strategies. Furthermore, we highlight recent developments in the design of MOF-polymer composites, which offer enhanced degradation performance and stability for practical applications in CWA degradation. These composite materials exhibit good performance in degrading chemical warfare agents, playing a crucial role in protecting public safety and maintaining national security. We can expect to see more breakthroughs in the application of metal-organic framework porous materials for degrading chemical warfare agents. It is hoped that these innovative materials will play a positive role in achieving social stability and security.

Synergistic cobalt‑copper metal-organic framework anchored amino-functionalized cellulose for antibiotic degradation: Interfacial engineering and mechanism insight

Improving electron transfer rate of Co species and inhibiting aggregation of metal-organic frameworks (MOFs) particles are essential prerequisites for activating advanced oxidation process in wastewater treatment field. Here, we exploit Cu species with variable valence states to accelerate electron transfer of Co species and then to boost the unsatisfactory degradation efficiency for refractory pharmaceuticals via in-situ growth of copper and cobalt species on l-lysine functionalized carboxylated cellulose nanofibers. Utilizing the synergistic interplay of Co sites and deliberately exposed Cu0/Cu1+ atoms, the subtly designed catalyst exhibited a surprising degradation efficiency (~100 %) toward tetracycline hydrochloride within 10 min (corresponding to a catalytic capacity of 267.71 mg/g) without adjusting temperature and pH. Meanwhile, the catalyst displays good recyclability, well tolerance for coexisting ions and excellent antibacterial performance derived from the intrinsic antibacterial property of Cu-MOF. This research provided a novel strategy to construct MOFs-cellulose materials toward degrading various stubborn antibiotic pollutants.

In situ growth of Zr-based metal-organic frameworks on cellulose sponges for Hg2+ and methylene blue removal

Metal-organic frameworks (MOFs) are characterised by high porosity levels and controllable structures, making them ideal adsorbents for wastewater. However, obtaining substrate materials with mechanical stability, excellent pore accessibility, and good processability for compositing MOF crystal powders to adsorb multiple pollutants in complex aqueous environments is challenging. In this study, porous MOFs@ modified cellulose sponge (MCS) composites were fabricated using MCS as a scaffold to provide anchoring sites for the coordination of Zr4+ ions and further in situ synthesis of MOFs, namely UiO-66@MCS and UiO-66-NH2@MCS, which effectively removed heavy metal ions and organic dyes. MOFs@MCS composites exhibit excellent water and dimensional stability, maintaining the pore structure by ambient drying during reuse. Compared with UiO-66@MCS composite, UiO-66-NH2@MCS composite exhibited a higher adsorption capacity of 224.5 mg·g-1 for Hg2+ and 400.9 mg·g-1 for methylene blue (MB). The adsorption of Hg2+ onto the MOFs@MCS composites followed the Langmuir and pseudo-second-order models, whereas the Freundlich and pseudo-second-order models were more suitable for MB adsorption. Moreover, the MOFs@MCS composites exhibited excellent reusability and were selective for the removal of Hg2+. Overall, this approach effectively combines Zr-based MOFs with mechanically and dimensionally stable porous cellulose sponges, rendering the approach suitable for purifying complex wastewater.

Starfruit-Shaped Zirconium Metal-Organic Frameworks: From 3D Intermediates to 2D Nanosheet Petals with Enhanced Catalytic Activity

We present the fabrication of a novel Starfruit-shaped metal-organic framework (SMOF) composed of zirconium and Tetra(4-carboxyphenyl)porphine linkers. The SMOF exhibits a unique morphology with edge-sharing two-dimensional (2D) nanosheet petals. Our investigation unravels a captivating transformation process, wherein three-dimensional (3D) shuttle-shaped MOFs form initially and subsequently evolve into 2D nanosheet-based SMOF structures. The distinct morphology of SMOF showcases superior catalytic activity in detoxifying G-type nerve agent and blister agent simulants, surpassing that of its 3D counterparts. This discovery of the 3D-to-2D transition growth pathway unlocks exciting opportunities for exploring novel strategies in advanced MOF nanostructure development, not only for catalysis but also for various other applications.

Robust and highly reactive membranes for continuous disposal of chemical warfare agents: Effects of nanostructure and functionality in MOF and nanochitin aerogel composites

Developing appropriate disposal of stockpiles of chemical warfare agents (CWAs) has gained significant attention as their lethal toxicity seriously harms humanity. In this study, a novel green-fabrication method with UiO-66 catalysts and amine-functionalized chitin nanofibers (ChNFs) was suggested to prepare durable and highly reactive membranes for decomposing chemical warfare agents (CWAs) in the continuous flow system. The strong interaction between ChNFs and the UiO-66 led to stable loading of the UiO-66 on the continuous nano-porous channel of the ChNF reactive membrane even with high loading of UiO-66 (70 wt% of UiO-66 in the ChNF substrate). In addition, the Brønsted base functionalities (-NH2 and -NHCOCH3) of the ChNF enhanced the catalytic activity and recyclability of the UiO-66. The resulting 70-ChNF composites can effectively decompose a nerve agent simulant (methyl paraoxon) even after 7 repeatable cycles, which has been not obtained in the previous UiO-66 catalyst. The ChNF/UiO-66 reactive membranes with 1 m2 of the area decomposed 130 g of CWAs within an hour in a continuous flow system. We believe these robust and highly reactive membranes can provide a sustainable and efficient solution for the massive CWA disposal and also contribute to the advancement of functional membrane material science.

Construction of imidazole@defective hierarchical porous UiO-66 and fibrous composites for rapid and nonbuffered catalytic hydrolysis of organophosphorus nerve agents

Hydrolytic destruction of toxic organophosphorus nerve agents by metal-organic framework (MOF) catalysts is commonly reliant on bulk water and volatile liquid base, preventing real-world implementation. Poor accessibility to MOF-based active sites in heterogeneous catalysis is also a crucial factor since reactants diffusion is limited by inherently small micropores. To overcome these practical limitations, a ligand-selective pyrolysis strategy was used to construct unsaturated Zr defects and additional mesopores in UiO-66(Zr). Owing to synergistic effect of Zr defects and hierarchical pores, hydrolysis rate constant (k) of nerve agent simulant DMNP (dimethyl 4-nitrophenyl phosphate) on optimal DHP-UiO-30% (defective hierarchical porous UiO-66) is 3.2 times higher than counterpart UiO-30% in N-ethylmorpholine buffer. Encapsulating imidazole (Im) into DHP-UiO-30% affords Im@DHP-UiO, mimicking phosphotriesterase. Im-72@DHP-UiO exhibits rapid DMNP detoxification with 99% conversion in 12 min and initial half-life (t1/2) of 1.8 min in nonbuffered water. As the first example of 'three-in-one' detoxifier, Im@DHP-UiO is further integrated onto nonwoven fabric to construct Im@DHP/Fiber, achieving solid-phase detoxification at ambient humidity with t1/2 of 19.6 min and final conversion of 91%. This is comparable to many powdered catalysts in aqueous solution buffered by volatile bases. This unified strategy is critical and viable to efficiently hydrolyze nerve agents in practical settings.

Multi-functional nanocellulose based nanocomposites for biodegradable food packaging: Hybridization, fabrication, key properties and application

Nowadays, non-degradable plastic packaging materials have caused serious environmental pollution, posing a threat to human health and development. Renewable eco-friendly nanocellulose hybrid (NCs-hybrid) composites as an ideal alternative to petroleum-based plastic food packaging have been extensively reported in recent years. NCs-hybrids include metal, metal oxides, organic frameworks (MOFs), plants, and active compounds. However, no review systematically summarizes the preparation, processing, and multi-functional applications of NCs-hybrid composites. In this review, the design and hybridization of various NCs-hybrids, the processing of multi-scale nanocomposites, and their key properties in food packaging applications were systematically explored for the first time. Moreover, the synergistic effects of various NCs-hybrids on several properties of composites, including mechanical, thermal, UV shielding, waterproofing, barrier, antimicrobial, antioxidant, biodegradation and sensing were reviewed in detailed. Then, the problems and advances in research on renewable NCs-hybrid composites are suggested for biodegradable food packaging applications. Finally, a future packaging material is proposed by using NCs-hybrids as nanofillers and endowing them with various properties, which are denoted as "PACKAGE" and characterized by "Property, Application, Cellulose, Keen, Antipollution, Green, Easy."

Humidity Enhances the Solid-Phase Catalytic Ability of a Bulk MOF-808 Metal-Organic Gel toward a Chemical Warfare Agent Simulant

Zirconium-based metal-organic frameworks have emerged as promising materials for detoxifying chemical warfare agents (CWAs) due to their remarkable stability and porosity. However, their practical application is hindered by issues with their powder form and poor catalytic performance in solid-phase degradation. To address these challenges, herein, a granular MOF-808 metal-organic gel (G808) is prepared under optimized conditions for catalytic degradation of the simulant 2-chloroethyl ethyl sulfide (2-CEES), a sulfide blister agent, in a neat state under different humidity conditions. The detoxification performance of G808 toward 2-CEES is significantly enhanced as the content of water present increases. The half-life of 2-CEES decontaminated by G808 can be shortened to 816 s, surpassing those of many other benchmark materials. To confirm the mechanism of catalytic degradation, we used gas chromatography, gas chromatography-mass spectrometry, and theoretical calculations. The findings revealed that hydrolysis was the predominant route. Additionally, granular G808 was reusable and adaptable to high-moisture environments, making it an excellent protective material with practical potential.

Cellulose-based adsorbents for solid phase extraction and recovery of pharmaceutical residues from water

Cellulose has attracted interest from researchers both in academic and industrial sectors due to its unique structural and physicochemical properties. The ease of surface modification of cellulose by the integration of nanomaterials, magnetic components, metal organic frameworks and polymers has made them a promising adsorbent for solid phase extraction of emerging contaminants, including pharmaceutical residues. This review summarizes, compares, and contrasts different types of cellulose-based adsorbents along with their applications in adsorption, extraction and pre-concentration of pharmaceutical residues in water for subsequent analysis. In addition, a comparison in efficiency of cellulose-based adsorbents and other types of adsorbents that have been used for the extraction of pharmaceuticals in water is presented. From our observation, cellulose-based materials have principally been investigated for the adsorption of pharmaceuticals in water. However, this review aims to shift the focus of researchers to the application of these adsorbents in the effective pre-concentration of pharmaceutical pollutants from water at trace concentrations, for quantification. At the end of the review, the challenges and future perspectives regarding cellulose-based adsorbents are discussed, thus providing an in-depth overview of the current state of the art in cellulose hybrid adsorbents for extraction of pharmaceuticals from water. This is expected to inspire the development of solid phase exraction materials that are efficient, relatively cheap, and prepared in a sustainable way.

Metal-Organic Framework Gels for Adsorption and Catalytic Detoxification of Chemical Warfare Agents: A Review

Chemical warfare agents (CWAs) have brought great threats to human life and social stability, and it is critical to investigate protective materials. MOF (metal-organic framework) gels are a class with an extended MOF architecture that are mainly formed using metal-ligand coordination as an effective force to drive gelation, and these gels combine the unique characteristics of MOFs and organic gel materials. They have the advantages of a hierarchically porous structure, a large specific surface area, machinable block structures and rich metal active sites, which inherently meet the requirements for adsorption and catalytic detoxification of CWAs. A series of advances have been made in the adsorption and catalytic detoxification of MOF gels as chemical warfare agents; however, overall, they are still in their infancy. This review briefly introduces the latest advances in MOF gels, including pure MOF gels and MOF composite gels, and discusses the application of MOF gels in the adsorption and catalytic detoxification of CWAs. Meanwhile, the influence of microstructures (pore structures, metal active site, etc.) on the detoxification performance of protective materials is also discussed, which is of great significance in the exploration of high-efficiency protective materials. Finally, the review looks ahead to next priorities. Hopefully, this review can inspire more and more researchers to enrich the performance of MOF gels for applications in chemical protection and other purification and detoxification processes.

Reactivity of [(PNP)Mn(CO)2] with Organophosphates

Organophosphorus nerve agents (OPAs) are a toxic class of synthetic compounds that cause adverse effects with many biological systems. Development of methods for environmental remediation and passivation has been ongoing for years. However, little progress has been made in therapeutic development for exposure victims. Given the postexposure behavior of OPA materials in enzymes such as acetylcholinesterase (AChE), development of electrophilic compounds as therapeutics may be more beneficial than the currently employed nucleophilic countermeasures. In this report, we present our studies with an electrophilic, 16-electron manganese complex (iPrPNP)Mn(CO)2 (1) and the nucleophilic hydroxide derivative (iPrPNHP)Mn(CO)2(OH) (2). The reactivity of 1 with phosphorus acids and the reactivity of 2 with the P-F bond of diisopropylfluorophosphate (DIPF) were studied. The role of water in both nucleophilic and electrophilic reactivity was investigated with the use of 17O-labeled water. Promising results arising from reactions of both 1 and 2 with organophosphorus substrates are reported.

Advances in Application of Cellulose-MOF Composites in Aquatic Environmental Treatment: Remediation and Regeneration

Metal organic frameworks (MOFs) have gained remarkable interest in water treatment due to their fascinating characteristics, such as tunable functionality, large specific surface area, customizable pore size and porosity, and good chemical and thermal stability. However, MOF particles tend to easily agglomerate in nanoscale, thus decreasing their activity and processing convenience. It is necessary to shape MOF nanocrystals into maneuverable structures. The in situ growth or ex situ incorporation of MOFs into inexpensive and abundant cellulose-family materials can be effective strategies for the stabilization of these MOF species, and therefore can make available a range of enhanced properties that expand the industrial application possibilities of cellulose and MOFs. This paper provides a review of studies on recent advances in the application of multi-dimensional MOF-cellulose composites (e.g., aerogels, membranes, and bulk materials) in wastewater remediation (e.g., metals, dyes, drugs, antibiotics, pesticides, and oils) and water regeneration by adsorption, photo- or chemocatalysis, and membrane separation strategies. The advantages brought about by combining MOFs and cellulose are described, and the performance of MOF-cellulose is described and compared to its counterparts. The mechanisms of relative MOF-cellulose materials in processing aquatic pollutants are included. Existing challenges and perspectives for future research are proposed.

Metal-organic frameworks/cellulose hybrids with their modern technological implementation towards water treatment

Metal-organic frameworks (MOFs) are amongst the most attractive porous polymeric networks with appealing properties. However, their inherent fragility, powder nature, low processibility, and handling present some exceptional challenges for high-tech commercial applications. Currently, economic and environmental concerns drive the development of some bioinspired polymeric matrices containing MOFs. As an artifact, the availability of previously unattainable properties is negotiated by conjugating cellulosic materials with crystalline MOFs. Thus, multi-dimensional organic-inorganic hybrid composites are formed with high electrical, optical, mechanical, and thermal features. These MOF/cellulose hybrids, known as CelloMOFs (cellulose MOFs), have remarkable mechanical properties with tunable porosities, specific surface area and accessible active sites, making them ideal for real-world troubleshooting applications such as wastewater treatment, chemical sensing, energy storage, and so on. In this review, current state-of-the-art strategic synthesis routes for fabrication of MOF/cellulose composites with a specific focus on CelloMOFs as a potential tool for mitigation of the targeted emerging water contaminants have been done under the same umbrella, which has previously been less explored. Streamlining discussions on general properties such as raw material selection, structural analysis of cellulose, availability of surface functional groups, cellulose-metal node interactions, cellulose charging, and so on have been emphasized, as has integration with robust MOFs. A better understanding of these fundamental properties is critical because they will have a significant impact on the performance of MOF/cellulose composites in a variety of applications. Furthermore, at the end of this review, the challenges and perspectives of using CelloMOFs have been discussed in a concise manner in order to improve their practical utility rather than just concept mapping.

Porphyrin-Moiety-Functionalized Metal-Organic Layers Exhibiting Catalytic Capabilities for Detoxifying Nerve Agent and Blister Agent Simulants

The development of very efficient bifunctional catalysts for the simultaneous detoxification of two kinds of the deadliest chemical warfare agents (CWAs), nerve agent and blister agent, is highly desirable. In this study, two porphyrin-based ligands [tetrakis(4-carboxyphenyl) porphyrin (TCPP) and protoporphyrin IX (PPIX)] are introduced into 2D Zr-1,3,5-tris(4-carboxyphenyl)benzene (BTB) metal-organic layers (MOLs), composed of six-connected Zr₆ nodes and the tritopic carboxylate ligand BTB, by a solvent-assisted ligand incorporation method. The loads of TCPP and PPIX are 6.4 and 10.9 wt %, respectively. The detoxification of simulants of the nerve agent and the blister agent was conducted to investigate the catalytic activity of porphyrin-moiety-functionalized MOLs. The reaction half-life of optimal TCPP-functionalized MOL catalyzing the hydrolysis of a nerve agent simulant is only 2.8 min, meanwhile, the half-life of the selective catalytic oxidation of a blister agent simulant is only 1.2 min under LED illumination. More importantly, such a degradation half-life is only about 4 min under natural sunlight (∼60 mW/cm²). To our knowledge, TCPP-functionalized MOL is by far the most efficient catalyst for blister agent simulant degradation under solar light. Therefore, 2D ultrathin MOLs on demand appear to be a promising and efficient material platform for the development of bifunctional catalysts for CWA protection.

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

Environmental pollution has drawn forth advanced materials and progressive techniques concentrating on sustainable development. Metal-organic frameworks (MOFs) have aroused vast interest resulting from their excellent property in structure and function. Conversely, powdery MOFs in highly crystalline follow with fragility, poor processability and recoverability. Aerogels distinguished by the unique three-dimensional (3D) interconnected pore structures with high porosity and accessible surface area are promising carriers for MOFs. Given these, combining MOFs with aerogels at molecule level to obtain advanced composites is excepted to further enhance their performance with higher practicability. Herein, we focus on the latest studies on the MOFs@aerogel composites. The construction of MOFs@aerogel with different synthetic routes and drying methods are discussed. To explore the connection between structure and performance, pore structure engineering and quantitation of MOFs content are outlined. Furthermore, various types of MOFs@aerogel composites and their carbonized derivatives are reviewed, as well as the applications of MOFs@aerogel for environmental remediation referring to water purification and air clearing. More importantly, outlooks towards these emerging advanced composites have been presented from the perspective of practical application and future development.

Phytic Acid Doped Polyaniline as a Binding Coating Promoting Growth of Prussian Blue on Cotton Fibers for Adsorption of Copper Ions

In recent years, the elimination of heavy metals from wastewater has become an important topic due to rapid industrialization, and it is of considerable interest to develop renewable and degradable materials for this purpose. In this work, a novel Prussian blue/polyaniline@cotton fibers (PB/PANI@CFs) composite was fabricated by a two-step process. Phytic acid doped PANI as a binding coating greatly promoted both the growth of PB and the adsorption of Cu2+. The deposition ratio of PB was as high as 24.68%. Scanning electron microscopy (SEM) displayed that PB nanoparticles were grown more uniformly in the composite and formed a perfect nanocube structure compared with PB@CFs. The successful deposition of both PB and PANI on CFs was demonstrated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FITR), and X-ray photoelectron spectroscopy (XPS). The effect of adsorption time, adsorbent dose, initial pH value, and initial copper sulphate concentration on the adsorption of PB/PANI@CFs composite for Cu2+ was studied by static adsorption and was compared with those of PANI@CFs and PB@CFs. The results showed that the maximum removal efficiency of Cu2+ by PB/PANI@CFs can reach 93.4% within 5 h, and the maximum adsorption capacity of Cu2+ can reach 31.93 mg·g−1. The adsorption of Cu2+ on PB/PANI@CFs followed the pseudo-second order kinetic model and conformed to the Freundlich adsorption isothermal model. The PB-functionalized CFs provided new insights into the design of efficient and low-cost absorbents for heavy metal remediation. The proposed process solves two problems simultaneously, i.e., the utilization of environmentally friendly and biodegradable biomass resources and the adsorption of heavy metal ions, and is a good approach to achieve high-quality and sustainable development.

Methyl Orange-Doped Polypyrrole Promoting Growth of ZIF-8 on Cellulose Fiber with Tunable Tribopolarity for Triboelectric Nanogenerator

Cellulose fiber (CelF) is a biodegradable and renewable material with excellent performance but negligible triboelectric polarizability. Methods to enhance and rationally tune the triboelectric properties of CelF are needed to further its application for energy harvesting. In this work, methyl-orange-doped polypyrrole (MO-PPy) was in situ coated on CelF as a mediating layer to promote the growth of metal–organic framework ZIF-8 and to construct a cellulose-based triboelectric nanogenerator (TENG). The results showed that a small amount of MO-PPy generated in situ significantly promoted the growth of ZIF-8 on CelF, and the ZIF-8 deposition ratio was able to increase from 7.8% (ZIF-8/CelF) to 31.8% (ZIF-8/MO-PPy@CelF). ZIF-8/MO-PPy@CelF remained electrically conductive and became triboelectrically positive, and the triboelectricity’s positivity was improved with the increase in the ZIF-8 deposition ratio. The cellulose-based TENG constructed with ZIF-8/MO-PPy@CelF (31.8% ZIF-8 deposition ratio) and polytetrafluoroethylene (PTFE) could generate a transfer charge of 47.4 nC, open-circuit voltage of 129 V and short-circuit current of 6.8 μA—about 4 times higher than those of ZIF-8/CelF (7.8% ZIF-8 deposition ratio)—and had excellent cycling stability (open-circuit voltage remained almost constant after 10,000 cycles). MO-PPy not only greatly facilitated the growth of ZIF-8 on CelF, but also acted as an electrode active phase for TENG. The novel TENG based on ZIF-8/MO-PPy@CelF composite has cheerful prospects in many applications, such as self-powered supercapacitors, sensors and monitors, smart pianos, ping-pong tables, floor mats, etc.

Cellulose based hyper-crosslinked polymer for efficiently recovering valuable materials from PO/SM wastewater

Herein, a TEMPO-oxidized cellulose-grafted-polystyrene hypercrosslinked polymer (TOC-PS-HCP) was synthesized facilely by TEMPO oxidation, grafting copolymerization and post crosslinking route. Based on the structural characterization, it was confirmed that TOC-PS-HCP mainly consisted of polystyrene chain on cellulose and rigid crosslinked bridge. Additionally, the as-prepared TOC-PS-HCP displayed appropriate hydrophobicity (water contact angle = 102.44°) and high specific surface area (S_BET = 601.20 m²·g^--1), which could efficiently recover ethylbenzene and styrene from PO/SM wastewater. The adsorption experiment was conducted to study the recovery performance for ethylbenzene and styrene in the aqueous phase. The results showed that TOC-PS-HCP could recover ethylbenzene and styrene quickly by adsorption process, and maintain a stable recovery rate both in different aqueous conditions and recycle experiments. The adsorption experiment in the simulated wastewater solution showed that TOC-PS-HCP exhibited the greater affinity for ethylbenzene and styrene than other substrates. Furthermore, a possible mechanism for the efficient recovery of ethylbenzene and styrene was suggested on the basis of experimental and theoretical results, which may be associated with van der Waals force and π-π stacking.

Cellulose-Based Hybrid Aerogels: Strategies toward Design and Functionality

The brittle nature of early aerogels developed from inorganic precursors fueled the discovery of their organic counterparts. Prominent among these organics are cellulose aerogels because of their natural abundance, biocompatibility, sustainable precursors, and tunable properties. The hierarchical structure of cellulose, from polymers to nano/microfibers, further facilitates fabrication of materials across multiple length scales with added applicability. However, the inherent flammability, structural fragility, and low thermal stability have limited their use. Recently developed cellulose-based hybrid aerogels offer strong potential owing to their tunability and enhanced functionality brought about by combining the inherent properties of cellulose with organic and inorganic components. A survey of the historical background and scientific achievements in the design and development of cellulose-based hybrid aerogel materials is encompassed here. The impacts of incorporating organic and inorganic ingredients with cellulose and the corresponding synergistic effects are discussed in terms of their design and functionality. The underlying principles governing the structural integration and functionality enhancement are also analyzed. The latest developments of cellulose-based hybrid aerogels fabricated from nontraditional incipient aerogels, such as fibrous webs, are also explored. Finally, future opportunities that could make these materials achieve even greater impacts through improved scalability, rationally designed synthesis, and multifunctional properties are discussed.

Nanoflake-Engineered Zirconic Fibrous Aerogels with Parallel-Arrayed Conduits for Fast Nerve Agent Degradation

Chemical warfare agents (CWAs) pose huge threats to ecological environments, agriculture, and human health due to the turbulent international situation in contemporary society. Zirconium hydroxide (Zr(OH)₄) has captured the prime focus as an effective candidate for CWA decomposition but is often hindered by the isolated powder form. Here, we demonstrate a scalable three-dimensional space-confined synthetic strategy to fabricate nanoflake-engineered zirconic fibrous aerogels (NZFAs). Our strategy enables the stereoscopic Zr(OH)₄ nanoflakes vertically and evenly in situ grown on the interconnected fibrous framework, remarkably enlarging the surface area and providing rich active sites for CWA catalysis. The as-synthesized NZFAs exhibit intriguing properties of ultralow density (>0.37 mg cm^-3), shape-memory behavior under 90% strain, and robust fatigue resistance over 10⁶ compression cycles at 40% strain. Meanwhile, the high air permeability, prominent adsorptivity, and reusability make them state-of-the-art chemical protective materials. This work may provide an avenue for developing next-generation aerogel-based catalysts and beyond.

De-Doped Polyaniline as a Mediating Layer Promoting In-Situ Growth of Metal-Organic Frameworks on Cellulose Fiber and Enhancing Adsorptive-Photocatalytic Removal of Ciprofloxacin

New kinds of inorganic–organic hybrid porous materials, metal–organic frameworks (MOFs), have shown great application potential in various fields, but their powdery nature limits their application to a certain extent. As a green and renewable biomass material in nature, cellulose fiber (CelF) has the advantages of biodegradability, recyclability and easy processing, and can be used as an excellent flexible substrate for MOFs. However, the efficient deposition of MOFs on CelF is still a great challenge for the development of this new material. Herein, polyaniline (PANI) and de-doped PANI (DPANI) with rich functional groups as a mediating layer was proposed to promote the in-situ growth and immobilization of some MOFs on CelF. The PANI (especially DPANI) layer greatly promoted the deposition of the four MOFs, and more encouragingly, significantly promoted the in-situ growth and nanocrystallization of MIL-100(Fe). MIL-100(Fe)@DPANI@CelF was selected as an adsorbent-photocatalyst to be used for the adsorptive-photocatalytic removal of ciprofloxacin (CIP) in water. The removal efficiency of CIP by MIL-100(Fe)@DPANI@CelF reached 82.78%, and the removal capacity of CIP was as high as 105.96 mg g⁻¹. The study found that DPANI had a synergistic effect on both the in-situ growth of MIL-100(Fe) on CelF and the adsorption-photocatalysis of CIP in water. The universal platform of PANI-mediated in-situ growth and immobilization of MOFs on CelF constructed in this study widens the road for the development of MOF@CelF composites.

Photo-assisted enhancement performance for rapid detoxification of chemical warfare agent simulants over versatile ZnIn2S4/UiO-66-NH2 nanocomposite catalysts

Constructing versatile materials with self-detoxification properties are highly desired for emergency destruction of chemical warfare agents (CWAs). Herein, we first reported in-situ fabrication of ZnIn₂S₄/UiO-66-NH₂ nanocomposites (ZnInS/UiO) and their application in catalytic detoxification of two CWA simulants. For nerve agent simulant dimethyl 4-nitrophenyl phosphate (DMNP), the optimal ZnInS/UiO-23.9 displayed 5.9 times increase in hydrolysis rate having the turnover frequency (TOF) of 0.0586 s^-1 under simulated solar light (SSL), which is superior to the reported UiO-based catalysts. Photo-assisted enhancement in DMNP detoxification was due to photothermal effect of ZnInS and close interfacial contact in ZnInS/UiO heterostructures, facilitating instantaneous heat transfer from ZnInS to UiO catalytic sites. As for mustard gas surrogate 2-chloroethyl ethyl sulfide (CEES), under SSL irradiation for 15 min, ZnInS/UiO-23.9 can eliminate 96.7% of CEES in droplet experiment, being 4.17 and 3.24 times of ZnInS and UiO accordingly. It was ascribed to spatial separation of photoinduced electron-hole pairs and photothermally-assisted charge transfer in ZnInS/UiO composites, improving catalytic activity for CEES detoxification. Besides, the detected products suggested that CEES conversion underwent reductive dechlorination, radical reactions and hydrolysis. This study can be extended to other multifunctional catalysts based on metal-organic frameworks and provides new opportunities for photoassisted enhanced detoxification of CWAs.

Facile Synthesis of Metal-Organic Layers with High Catalytic Performance toward Detoxification of a Chemical Warfare Agent Simulant

Two-dimensional (2D) metal-organic layer (MOL) materials are highly desired against chemical warfare agents (CWAs). However, the rapid synthesis of 2DMOLs with open metal sites in a single step is very challenging. Herein, a facile bottom-up method for synthesizing MOLs with microwave assistance is applied to produce Zr/Hf-BTB MOLs, composed of six-connected M₆O₄(OH)₄¹²⁺ and the tritopic carboxylate ligand 1,3,5-tris(4-carboxyphenyl)benzene (BTB). The synthesis and ligand exchange steps can be combined into a single step to yield MOLs with active open sites directly. The as-synthesized MOLs demonstrate excellent catalytic performance toward the degradation of a CWA simulant. The theoretical calculations confirm that the high catalytic activity is due to the formate groups coordinated to the metal nodes being replaced by hydroxyl groups. The present work not only develops a method for the fast synthesis of 2D MOLs with active open metal sites in a single step but also provides a first demonstration for the application of 2D metal coordination materials in CWA protection.

Robust Nanocellulose/Metal-Organic Framework Aerogel Composites: Superior Performance for Static and Continuous Disposal of Chemical Warfare Agent Simulants

Environment-friendly and robust nanocellulose/metal-organic framework aerogel composites were prepared for effective detoxification of chemical warfare agent simulants both in static and dynamic continuous flow systems. For this, we fabricated a durable porous composite of the UiO-66 catalyst and TEMPO-oxidized cellulose nanofibers (TOCN) to examine as a detoxification filter. Even with over 50 wt % UiO-66, the obtained cellulose aerogel composites exhibited high stability without leaking of UiO-66 for 4 weeks under an aqueous state. The cellulose aerogel composite with 54 wt % UiO-66 showed a quite high surface area (483 m² g^-1) despite the presence of TOCN, which caused fast degradation of methyl paraoxon (MPO), a nerve agent simulant, with a 0.7 min half-life in an aqueous solution with N-ethylmorpholine buffer. This aerogel composite was then examined as the detoxification filter in the continuous flow system under a 7.2 mL h^-1 flow rate, which surprisingly decomposed 53.7 g of MPO within 1 h with 1 m² of the effective area.

One-flow upscaling neutralization of an organophosphonate-derived pesticide/nerve agent simulant to value-added chemicals in a novel Teflon microreactor platform

Synthesizing value-added products from chemical warfare agents is a concept well beyond the usual notion of simply neutralizing the agents.

Chemical targets to deactivate biological and chemical toxins using surfaces and fabrics

The most recent global health and economic crisis caused by the SARS-CoV-2 outbreak has shown us that it is vital to be prepared for the next global threat, be it caused by pollutants, chemical toxins or biohazards. Therefore, we need to develop environments in which infectious diseases and dangerous chemicals cannot be spread or misused so easily. Especially, those who put themselves in situations of most exposure - doctors, nurses and those protecting and caring for the safety of others - should be adequately protected. In this Review, we explore how the development of coatings for surfaces and functionalized fabrics can help to accelerate the inactivation of biological and chemical toxins. We start by looking at recent advancements in the use of metal and metal-oxide-based catalysts for the inactivation of pathogenic threats, with a focus on identifying specific chemical bonds that can be targeted. We then discuss the use of metal-organic frameworks on textiles for the capture and degradation of various chemical warfare agents and their simulants, their long-term efficacy and the challenges they face.

HKUST-1 modified ultrastability cellulose/chitosan composite aerogel for highly efficient removal of methylene blue

A novel composite HKUST-1/cellulose/chitosan aerogel (HKUST-1/CCSA) as an efficient adsorbent with hierarchical pores was prepared through a facile in situ growth way combining covalent cross-linking, vacuum freeze-drying, and solvothermal methods. By incorporating with cellulose (CE), covalently cross-linked cellulose (CE)/chitosan (CS) composite aerogel exhibits good stability, maintaining fine morphology and structures in acidic solutions under solvothermal conditions. Meantime, a high content of CS is beneficial to enhancing the growth of HKUST-1. Finally, the mass loading ratio of HKUST-1 is as high as 42.54 % in HKUST-1/CCSA. The BET specific surface area of HKUST-1/CCSA reaches 457.75 m² g^-1, which is much larger than that of CCSA (9.74 m² g^-1). HKUST-1/CCSA was applied to remove methylene blue with high adsorption capacity (526.3 mg g^-1) and good recycling capability. This strategy can provide an effective and facile pathway to prepare ultra-stable polysaccharide-based composite aerogel with high specific surface area and hierarchical pores, branching out more applications in pollutant treatment fields.

Facile preparation and adsorption performance of low-cost MOF@cotton fibre composite for uranium removal

A novel composite MOF@cotton fibre (HCF) was prepared and characterized by FTIR, SEM, XPS and TGA. The effect of various parameters on the adsorption efficiency, such as the solution pH, contact time, initial U(VI) concentration and temperature, was studied. The maximal sorption capacity (Qm) is 241.28 mg g-1 at pH 3.0 for U(VI) according to the Langmuir isotherm adsorption model, and the kinetic and thermodynamic data reveal a relatively fast entropy-driven process (ΔH0 = 13.47 kJ mol-1 and ΔS0 = 75.47 J K-1 mol-1). The removal efficiency of U(VI) by HCF is comparable with that of pure cotton fibre and as-prepared MOF (noted as HST). However, the HST composite with cotton fibre significantly improved the treatment process of U(VI) from aqueous solutions in view of higher removal efficiency, lower cost and faster solid-liquid separation. Recycling experiments showed that HCF can be used up to five times with less than 10% efficiency loss.

Microwave-Assisted Solvothermal Synthesis of UiO-66-NH2 and Its Catalytic Performance toward the Hydrolysis of a Nerve Agent Simulant

Zr-containing metal-organic frameworks (MOFs) exhibit a good performance of catalyzing the hydrolysis of chemical warfare agents, which is closely related to the size of MOF particles and its defects, but these two factors are often intertwined. In this article, we synthesized UiO-66-NH2 nanoparticles using a microwave-assisted hydrothermal method. By using a new modulator 4-Fluoro-3-Formyl-Benzoic Acid (FFBA) in different proportions, MOF particles with the same defect degree but different scales and those with similar sizes but different defect degrees can be obtained. The performance of the obtained MOF particles to catalyze the hydrolysis of the nerve agent simulant, dimethyl 4-nitrophenyl phosphate (DMNP), was investigated, and the effects of single factors of size or defect were compared for the first time. As the size of the obtained MOF particles increased from 81 nm to 159 nm, the catalytic degradation efficiency toward DMNP gradually decreased, and the half-life increased from 3.9 min to 11.1 min. For MOFs that have similar crystal sizes, the catalytic degradation half-life of MOF3 is only 5 min, which is much smaller than that of MOF5 due to the defects increase from 1.2 to 1.8 per Zr6 cluster.

Continuous Flow Composite Membrane Catalysts for Efficient Decomposition of Chemical Warfare Agent Simulants

Continuous and safe decomposition of chemical warfare agents (CWAs) is a critical requirement to protect both soldiers and citizens and to eliminate the stockpiles after the cold war. The Zr-based metal-organic framework (Zr-MOF) has been known as the most effective catalyst for decomposing CWAs, especially the most fatal nerve agents, however, its low processability due to the powder form limits its expansion to actual military applications. To this end, the composite membrane catalysts (CMCs) comprising the Zr-MOF (UiO-66 catalyst) and nylon 6 nanofiber (porous supporter) are developed by the simple integration of electrospray and electrospinning, resulting in selective immobilization of UiO-66 on the surface of the nylon 6 nanofibers. These strategical benefits of CMCs gave super catalytic durability including recyclability over five times without decreasing the catalytic activity for the decomposition of methyl paraoxon (MPO), a simulant of the nerve agent, in the presence of N-ethylmorpholine (N-EM), which was not achieved in the original particulate UiO-66. Because of the excellent physical and chemical stabilities of CMCs, the CMC with 56 wt % of UiO-66 (CMC56) decomposed 198 g of MPO within an hour in the continuous flow system with a flow rate of 21.6 mL h^-1. This study highlights the important strategies in designing the feasible membrane-type catalysts with superior catalytic activity and robust durability for decomposing CWAs in the continuous flow system.

Metal oxide nanoparticles for the decontamination of toxic chemical and biological compounds

For several years, the international context is deeply affected by the use of chemical and biological weapons. The use of CBRN (Chemical Biological Radiological Nuclear) threat agents from military stockpiles or biological civilian industry demonstrate the critical need to improve capabilities of decontamination for civilians and military. Physical decontamination systems that operate only by adsorption and displacement such as Fuller's Earth, have the drawback of not neutralizing hazardous agents, giving place to cross contaminations. Consequently, the development of a formulation based on metal oxide nanoparticles attracts considerable interest, since they offer physicochemical properties that allow them to both adsorb and degrade toxic compounds. Thus, the aim of this study is to found metal oxide nanoparticles with a versatile activity on both chemical and biological toxic agents. Therefore, several metal oxides such as MgO, TiO₂, CeO₂, ZnO and ZrO₂ were characterized and their decontamination kinetics of less-toxic surrogate of VX, paraoxon, were studied in vitro. To determine the antimicrobial activity of these nanoparticles, simulants of biological terrorist threat were used by performing a 3-hours decontamination kinetics. This proof-of-concept study showed that MgO is the only one that exhibits both chemical and antibacterial actions but without sporicidal activity.

Recent advances in the shaping of metal–organic frameworks

In this review, the recent advances in the shaping of MOFs are overviewed, and some promising strategies recently developed are highlighted, including templated shaping, self-shaping, shaping on substrates, and shaping with sacrificial materials.

Layer-by-Layer Fabrication of Core-Shell Fe3O4@UiO-66-NH2 with High Catalytic Reactivity toward the Hydrolysis of Chemical Warfare Agent Simulants

Detoxifying materials against chemical warfare agents (CWAs) and their simulants are highly desired for proper handling of contamination by and destruction of CWAs. Herein, we report a facile layer-by-layer fabrication of core-shell Fe₃O₄@UiO-66-NH₂ and its application in fast degradation of CWA simulants. The Fe₃O₄@UiO-66-NH₂ composite was prepared through a layer-by-layer epitaxial growth strategy, by alternately immersing Fe₃O₄ nanoparticles in ethanol solutions of a metal node [Zr₆O₄(OH)₄]¹²⁺ precursor and organic linkers [NH₂-BDC, 2-aminoterephthalic acid], respectively, and separating using a magnet. As confirmed by characterization results, the Fe₃O₄@UiO-66-NH₂ composites with 24.4 μmol/g Zr₆ node content showed a well-defined core-shell structure as well as good thermal and chemical stability. These core-shell magnetic metal-organic frameworks (MOFs) were further tested in the catalytic hydrolysis of dimethyl-4-nitrophenyl phosphate (a nerve agent simulant) and demonstrated 36 times higher catalytic activity than the UiO-66-NH₂ powder due to their highly defective surface, high percentage of MOFs on the surface, and their rich mesoporous structure. Since magnetism was retained after the coating of MOFs, Fe₃O₄@UiO-66-NH₂ could be easily recovered and reused after catalysis.

Metal Hydroxide/Polymer Textiles for Decontamination of Toxic Organophosphates: An Extensive Study of Wettability, Catalytic Activity, and the Effects of Aggregation

Electrospun nanofibers (NFs) incorporated with catalytically active components have gained significant interest in chemical protective clothing. This is because of the desirable properties of the NFs combined with decontamination capability of the active component. Here, a series of metal hydroxide catalysts Ti(OH)_x, Zr(OH)₄, and Ce(OH)₄ were incorporated into three different polymer NF systems. These new polymer/metal hydroxide composite NFs were then evaluated for their catalytic activity against a nerve agent simulant. Two methods were utilized to incorporate the metal hydroxides into the NFs. Method one used direct incorporation of Ti(OH)_x, Zr(OH)₄, and Ce(OH)₄ catalysts, whereas method two employed incorporation of Ti(OH)_x via a precursor molecule. Composite NFs prepared via method one resulted in greatly improved reaction rates over the respective pure metal hydroxides due to reduced aggregation of catalysts, with polymer/Ce(OH)₄ composite NFs having the fastest reaction rates out of method one materials. Interestingly, composite samples prepared by method two yielded the fastest reaction rates overall. This is because of the homogeneous distribution of the metal hydroxide catalyst throughout the NF. This homogeneous distribution created a hydroxyl-decorated NF surface with a greater number of exposed active sites for catalysis. The hydroxyl-decorated NF surface also resulted in an unexpected highly wettable composite NF, which also was found to contribute to the observed reaction rates. These results are not only promising for applications in chemical protective clothing but also show great potential for application in areas which need highly wettable membrane materials. This includes areas such as separators, antifouling membranes, and certain medical applications.