Strong Foam-like Composites from Highly Mesoporous Wood and Metal-Organic Frameworks for Efficient CO2 Capture

Autonomous humidity regulation by MOF/wood composites

Maintaining indoor air relative humidity (R.H.) within the 40-60% range recommended by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) significantly impacts human comfort and health. However, conventional solutions like dehumidifiers and humidifiers increase energy consumption, challenging the building sector's carbon neutrality goals. Here, we present an innovative composite material comprising wood and metal-organic frameworks (MOFs) that passively regulates indoor humidity by absorbing and releasing moisture. Our universal fabrication strategy enhances wood scaffold accessibility and increases MOF loading, resulting in a significant surface area increase, surpassing previous MOF/wood composites. This MOF/wood composite exhibits remarkable water sorption capacity, autonomously maintaining indoor humidity around 45% R.H. without external energy consumption. This aligns with ASHRAE recommendations, offering indirect energy savings and promoting a health-friendly indoor environment. Furthermore, the MOF/wood composite outperforms many existing materials in mechanical strength, dimensional stability, and scalability, making it highly suitable for building applications and contributing to carbon neutrality in the building sector.

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.

Natural Wood-Derived Macroporous Cellulose for Highly Efficient and Ultrafast Elimination of Double-Stranded RNA from In Vitro-Transcribed mRNA

Double-stranded RNA (dsRNA) is a major impurity that can induce innate immune responses and cause adverse drug reactions. Removing dsRNA is an essential and non-trivial process in manufacturing mRNA. Current methods for dsRNA elimination use either high-performance liquid chromatography or microcrystalline cellulose, rendering the process complex, expensive, toxic, and/or time-consuming. This study introduces a highly efficient and ultrafast method for dsRNA elimination using natural wood-derived macroporous cellulose (WMC). With a naturally formed large total pore area and low tortuosity, WMC removes up to 98% dsRNA within 5 min. This significantly shortens the time for mRNA purification and improves purification efficiency. WMC can also be filled into chromatographic columns of different sizes and integrates with fast-protein liquid chromatography for large-scale mRNA purification to meet the requirements of mRNA manufacture. This study further shows that WMC purification improves the enhanced green fluorescent protein mRNA expression efficiency by over 28% and significantly reduces cytokine secretion and innate immune responses in the cells. Successfully applying WMC provides an ultrafast and efficient platform for mRNA purification, enabling large-scale production with significant cost reduction.

Robust functionalized cellulose-based porous composite for efficient capture and ultra-fast desorption of aqueous heavy metal pollution

The heavy metal pollution control industry requires convenient and cost-effective solutions to address complex aqueous environment. Adsorption method can be an effective strategy to realize these goals. Considering the importance of environmental and sustainable development strategies, there is an urgent need to develop efficient, green and non-toxic heavy metal adsorbents. In this work, a robust aminated cellulose-based porous adsorbent (PGPW) was developed from delignified wood and amino-rich polymer using a solvent-free, mild, simple and efficient preparation method. Such adsorbent exhibited excellent adsorption capacity (188.68 mg g-1) for Cu(II), and its adsorption behavior was consistent with pseudo-second order kinetic and Langmuir isotherm models. Notably, PGPW with superior compressibility could be squeezed to achieve rapid desorption and reach equilibrium within 5 min, while still retaining 87 % adsorption efficiency after 50 cycles. In addition, PGPW showed remarkable selectivity towards various coexisting ionic systems and demonstrated a considerable adsorption capacity in natural water applications. The adsorption mechanism of heavy metal ions on porous adsorption material was elucidated. This approach provides a simple, gentle and sustainable strategy for preparing functionalized wood-based composites with efficient adsorption and ultra-fast desorption of heavy metal ions.

Tailoring the topology of ZIF-67 metal-organic frameworks (MOFs) adsorbents to capture humic acids

Chlorination is a versatile technique to combat water-borne pathogens. Over the last years, there has been continued research interest to abate the formation of chlorinated disinfection by-products (DBPs). To prevent hazardous DBPs in drinking water, it is decided to diminish organic precursors, among which humic acids (HA) resulting from the decomposition and transformation of biomass. Metal-organic frameworks (MOFs) such as zeolitic imidazolate frameworks (ZIFs) have recently received tremendous attention in water purification. Herein, customized ZIF-67 MOFs possessing various physicochemical properties were prepared by changing the cobalt source. The HA removal by ZIF-67-Cl, ZIF-67-OAc, ZIF-67-NO3, and ZIF-67-SO4 were 85.6%, 68.9%, 86.1%, and 87.4%, respectively, evidently affected by the specific surface area. HA uptake by ZIF-67-SO4 indicated a removal efficiency beyond 90% in 4  90% after 60 min mixing the solution with 0.3 g L-1 ZIF-67-SO4. Notably, an acceptable removal performance (∼72.3%) was obtained even at HA concentrations up to 100 mg L-1. The equilibrium data fitted well with the isotherm models in the order of Langmuir> Hill > BET> Khan > Redlich-Peterson> Jovanovic> Freundlich > and Temkin. The maximum adsorption capacity qm for HA uptake by ZIF-67-SO4 was 175.89 mg g-1, well above the majority of adsorbents. The pseudo-first-order model described the rate of HA adsorption by time. In conclusion, ZIF-67-SO4 presented promising adsorptive properties against HA. Further studies would be needed to minimize cobalt leaching from the ZIF-67-SO4 structure and improve its reusability safely, to ensure its effectiveness and the economy of adsorption system.

Multiscale Porous Carbon Materials by In Situ Growth of Metal-Organic Framework in the Micro-Channel of Delignified Wood for High-Performance Water Purification

Porous carbon materials are suitable as highly efficient adsorbents for the treatment of organic pollutants in wastewater. In this study, we developed multiscale porous and heteroatom (O, N)-doped activated carbon aerogels (CAs) based on mesoporous zeolitic imidazolate framework-8 (ZIF-8) nanocrystals and wood using 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation, in situ synthesis, and carbonization/activation. The surface carboxyl groups in a TEMPO-oxidized wood (TW) can provide considerably large nucleation sites for ZIF-8. Consequently, ZIF-8, with excellent porosity, was successfully loaded into the TW via in situ growth to enhance the specific surface area and enable heteroatom doping. Thereafter, the ZIF-8-loaded TW was subjected to a direct carbonization/activation process, and the obtained activated CA, denoted as ZIF-8/TW-CA, exhibited a highly interconnected porous structure containing multiscale (micro, meso, and macro) pores. Additionally, the resultant ZIF-8/TW-CA exhibited a low density, high specific surface area, and excellent organic dye adsorption capacity of 56.0 mg cm-3, 785.8 m2 g-1, and 169.4 mg g-1, respectively. Given its sustainable, scalable, and low-cost wood platform, the proposed high-performance CA is expected to enable the substantial expansion of strategies for environmental protection, energy storage, and catalysis.

Novel Core/Shell Nylon 6,6/La-TMA MOF Electrospun Nanocomposite Membrane and CO2 Capture Assessments of the Membrane and Pure La-TMA MOF

Membrane technology plays a vital, applicable, and essential role in human life and industry. The high adsorption capacity of membranes can be employed for capturing air pollutants and greenhouse gases. In this work, we tried to develop a shaped industrial form of a metal-organic framework as an adsorbent material with the ability to capture CO₂ in the laboratory phase. To do so, a core/shell Nylon 6,6/La-TMA MOF nanofiber composite membrane was synthesized. This organic/inorganic nanomembrane is a kind of nonwoven electrospun fiber that was prepared using the coaxial electrospinning approach. FE-SEM, surface area calculations, nitrogen adsorption/desorption, XRD grazing incidence on thin films, and histogram diagrams were applied to assess the quality of the membrane. This composite membrane as well as pure La-TMA MOF were assessed as CO₂ adsorbent materials. The CO₂ adsorption abilities of the core/shell Nylon 6,6/La-TMA MOF membrane and pure La-TMA MOF were as high as 0.219 and 0.277 mmol/g, respectively. As a result of preparing the nanocomposite membrane from microtubes of La-TMA MOF, the %A of the micro La-TMA MOF (% 43.060) increased to % 48.524 for Nylon 6,6/La-TMA MOF.

In situ growth of UiO-66-NH2 in wood-derived cellulose for iodine adsorption

The capture of radioactive iodine is an inevitable requirement in nuclear industry for environmental protection. Metal-organic frameworks (MOFs) are a new generation of sorbents that have wide applications for iodine adsorption and recovery. Although the loading of MOFs on wood can avoid the drawbacks of the powder form of MOFs in implementation, the dense structure of wood results in the lower loading, even after delignification, which limits the adsorption capacity. Herein, a hierarchically porous UiO-66-NH₂ @WCA composite was fabricated by in-situ synthesis of UiO-66-NH₂ in wood-derived cellulose aerogel (WCA) that was further removed hemicellulose from delignified wood. UiO-66-NH₂ @WCA exhibited a high loading (36 wt%) of UiO-66-NH₂ crystals and a high adsorption capacity of 704 mg/g for iodine vapor and 248 mg/g for iodine aqueous solution. The adsorption behavior in iodine aqueous solution was well predicted by the Freundlich isotherm and pseudo-second-order kinetic model. The adsorption capacity of UiO-66-NH₂ @WCA was highest in solution when the pH was 6, while the ionic strength had little effect. The hydroxyl groups on the WCA matrix had a charge transfer effect with iodine, providing additional sites for iodine capture. Furthermore, a packed column system was applied to demonstrate the excellent recyclability and potential for practical application.

High-Selective CO2 Capture in Amine-Decorated Al-MOFs

Amine-functionalized metal-organic framework (MOF) material is a promising CO₂ captor in the post-combustion capture process owing to its large CO₂ working capacity as well as high CO₂ selectivity and easy regeneration. In this study, an ethylenediamine (ED)-decorated Al-based MOFs (named ED@MOF-520) with a high specific area and permanent porosity are prepared and evaluated to study the adsorption and separation of CO₂ from N₂. The results show that ED@MOF-520 adsorbent displays a superior CO₂ capture performance with a CO₂/N₂ separation factor of 50 at 273 K, 185% times increase in the CO₂/N₂ separation efficiency in comparison with blank MOF-520. Furthermore, ED@MOF-520 exhibits a moderate-strength interaction with 29 kJ mol^-1 adsorption heat for CO₂ uptake, which not only meets the requirement of CO₂ adsorption but also has good cycle stability. This work provides a promising adsorbent with a high CO₂/N₂ separation factor to deal with carbon peak and carbon neutrality.

Wood-Based Self-Supporting Nanoporous Three-Dimensional Electrode for High-Efficiency Battery Deionization

Developing highly efficient advanced battery deionization (BDI) electrode materials at a low cost is vital for seawater desalination. Herein, a high-efficiency wood-based BDI electrode has been fabricated for seawater desalination, benefiting from the self-supporting three-dimensional (3D) nanoporous structure and rich redox-active sites. The finely tuned rich electrochemical redox active C═O groups on the surface of the wood electrode derived from the facile thermochemical conversion of lignin play a crucial role in the Faradaic cation removal dynamics of BDI. Coupling the 3D wood electrode and a polyaniline-modified wood electrode as the cathode and anode, an all-wood-electrode-based deionization battery has been successfully assembled with a state-of-the-art ion removal capacity of up to 164 mg g^-1 in seawater. Our work reported an example of utilizing wood as the BDI electrode via fine-tuning the redox-active sites, demonstrating a novel resource utilization pathway of converting cheap biomass into BDI electrodes for highly efficient seawater desalination.

Metal–Organic Frameworks (MOFs) Containing Adsorbents for Carbon Capture

In this study, new composite materials of montmorillonite, biochar, or aerosil, containing metal–organic frameworks (MOF) were synthesized in situ. Overall, three different MOFs—CuBTC, UTSA-16, and UiO-66-BTEC—were used. Obtained adsorbents were characterized using powder X-ray diffraction, thermogravimetric analysis, nitrogen adsorption porosimetry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectrophotometry. Additionally, the content of metallic and nonmetallic elements was determined to investigate the crystalline structure, surface morphology, thermal stability of the obtained MOF-composites, etc. Cyclic CO2 adsorption analysis was performed using the thermogravimetric approach, modeling adsorption from flue gasses. In our study, the addition of aerosil to CuBTC (CuBTC-A-15) enhanced the sorbed CO2 amount by 90.2% and the addition of biochar (CuBTC-BC-5) increased adsorbed the CO2 amount by 75.5% in comparison to pristine CuBTC obtained in this study. Moreover, the addition of montmorillonite (CuBTC-Mt-15) increased the adsorbed amount of CO2 by 27%. CuBTC-A-15 and CuBTC-BC-5 are considered to be the most perspective adsorbents, capturing 3.7 mmol/g CO2 and showing good stability after 20 adsorption-desorption cycles.

Environmentally Benign Biosynthesis of Hierarchical MOF/Bacterial Cellulose Composite Sponge for Nerve Agent Protection

The fabrication of MOF polymer composite materials enables the practical applications of MOF-based technology, in particular for protective suits and masks. However, traditional production methods typically require organic solvent for processing which leads to environmental pollution, low-loading efficiency, poor accessibility, and loss of functionality due to poor solvent resistance properties. For the first time, we have developed a microbial synthesis strategy to prepare a MOF/bacterial cellulose nanofiber composite sponge. The prepared sponge exhibited a hierarchically porous structure, high MOF loading (up to ≈90 %), good solvent resistance, and high catalytic activity for the liquid- and solid-state hydrolysis of nerve agent simulants. Moreover, the MOF/ bacterial cellulose composite sponge reported here showed a nearly 8-fold enhancement in the protection against an ultra-toxic nerve agent (GD) in permeability studies as compared to a commercialized adsorptive carbon cloth. The results shown here present an essential step toward the practical application of MOF-based protective gear against nerve agents.

Enhanced CO2 Adsorption and Selectivity of CO2/N2 on Amine@ZIF-8 Materials

The ZIF-8 crystals were successfully postsynthetically modified using methylamine (MA), ethylenediamine (ED), and N, N ${}^{\prime }$ -dimethylethylenediamine (MMEN) to improve their adsorption performance toward CO2. Results showed that, compared with the original ZIF-8, the BET specific surface area of MA-ZIF-8, MMEN-ZIF-8, and ED-ZIF-8 has increased by 118.2%, 92.0%, and 29.8%, respectively. In addition, their total pore volume increased separately by 130.8%, 100%, and 48.7%. The adsorption capacities of CO2 on the amine-modified ZIF-8 samples followed the order $\text{MA}-\text{ZIF}-8>\text{MMEN}-\text{ZIF}-8>\text{ED}-\text{ZIF}-8>\text{ZIF}-8$ . The CO2 adsorption capacities at 298 K on MA-ZIF-8, MMEN-ZIF-8, and ED-ZIF-8 were increased by 118.2%, 90.2%, and 29.8%, respectively. What is more, the CO2/N2 selectivities calculated using an IAST model of the amine@ZIF-8 samples at 0.01 bar and 298 K were also significantly improved and followed the order $\text{MA}-\text{ZIF}-8\left(31.4\right)>\text{ED}-\text{ZIF}-8\left(25.1\right)>\text{MMEN}-\text{ZIF}-8\left(14.1\right)>\text{ZIF}-8\left(11.5\right)$ , which increased by 173.0%, 121.4%, and 22.6%, respectively. The isosteric heat of CO2 adsorption ( $Q_{\text{st}}$ ) on the MA-ZIF-8, MMEN-ZIF-8, and ED-ZIF-8 all becomes higher, while $Q_{\text{st}}$ of N2 on these samples was slightly lower in comparison with that on the ZIF-8. Furthermore, after six recycle runs of gravimetric CO2 adsorption-desorption on MA-ZIF-8, the adsorption performance of CO2 is still very good, indicating that the MA-ZIF-8 sample has good regeneration performance and can be applied into industrial CO2 adsorption and separation.

In Situ Dry Chemical Synthesis of Nitrogen-Doped Activated Carbon from Bamboo Charcoal for Carbon Dioxide Adsorption

In this work, nitrogen-doped bamboo-based activated carbon (NBAC) was in situ synthesized from simply blending bamboo charcoal (BC) with sodamide (SA, NaNH₂) powders and heating with a protection of nitrogen flow at a medium temperature. The elemental analysis and X-ray photoelectron spectra of as-synthesized NBAC showed quite a high nitrogen level of the simultaneously activated and doped samples; an abundant pore structure had also been determined from the NBACs which has a narrow size distribution of micropores (<2 nm) and favorable specific surface area that presented superb adsorption performance. The fcarbon dioxide (CO₂) adsorption of the NBACs was measured at 0 °C and 25 °C at a pressure of 1 bar, whose capture capacities reached 3.68–4.95 mmol/g and 2.49–3.52 mmol/g, respectively, and the maximum adsorption could be observed for NBACs fabricated with an SA/BC ratio of 3:1 and activated at 500 °C. Further, adsorption selectivity of CO₂ over N₂ was deduced with the ideal adsorbed solution theory ((IAST), the selectivity was finally calculated which ranged from 15 to 17 for the NBACs fabricated at 500 °C). The initial isosteric heat of adsorption (Qst) of NBACs was also determined at 30–40 kJ/mol, which suggested that CO₂ adsorption was a physical process. The results of ten-cycle adsorption-desorption experimentally confirmed the regenerated NBACs of a steady CO₂ adsorption performance, that is, the as-synthesized versatile NBAC with superb reproducibility makes it a perspective candidate in CO₂ capture and separation application.

Metal-organic framework-encapsulated nanoparticles for synergetic chemo/chemodynamic therapy with targeted H2O2 self-supply

Nanocatalytic cancer therapy based on chemodynamic therapy, which converts hydrogen peroxide (H2O2) into toxic reactive oxygen species via the Fenton-like reaction, is regarded as a promising therapeutic strategy due to its specific response toward the tumor microenvironment (TME). However, the H2O2 concentration in TME (100 μM to 1 mM) is insufficient and introducing enough H2O2 or H2O2-generating agents is challenging. In view of this, we report a drug delivery system, CaO2/DOX@Cu/ZIF-8@HA (CDZH), which is capable of targeted H2O2 self-supply and exhibits outstanding chemo/chemodynamic synergetic therapy capability. CaO2/DOX@Cu/ZIF-8@HA is synthesized by fabricating biodegradable Cu/ZIF-8 shell-encapsulated CaO2 nanoparticles, loading chemotherapy drug doxorubicin, and coating a hyaluronic acid shell. In an acidic tumor microenvironment, the CDZH nanostructures targeted the release of doxorubicin, Cu2+, and CaO2. Doxorubicin affects chemotherapy and bioimaging, and CaO2 supplies H2O2 through a Cu-Fenton-like reaction to generate hydroxyl radicals with high oxidation activity for chemodynamic therapy. In brief, the drug delivery system combined targeted H2O2 self-supply and targeted bioimaging possess the potential of an efficient synergistic strategy for chemodynamic therapy and chemotherapy.