Ultrasonically synthesized MOFs for modification of polymeric membranes: A critical review

Enhanced Fenton-like reactions via interface electron reconstruction in low-crystallinity FeCo bimetallic metal-organic frameworks: Bidirectional control of Fe (III) and Co (II) sites

In this study, the activity and stability of Fenton-like reactions are enhanced by constructing a low-crystallinity FeCo bimetallic metal-organic framework (FeCox-BDC (BDC denotes as terephthalic acid)) through interface electron reconstruction. However, the specific origins and mechanisms of their enhanced activity, particularly in Fenton-like reactions, remains unclear. Systematic analysis revealed that the isomorphic substitution of Co (II) reduces the coordination number and d-electron count at local Fe (III) sites, shifting the d-band centers (-1.59 eV) closer to the Fermi level. Additionally, Co 3d-orbitals can accept electrons, improving the occupation of antibonding orbitals. Notably, Fe (III) and Co (II) sites exhibit a synergistic effect: Fe (III) sites strongly adsorbed the Oα point of the peroxy bond (lOαOβ), while Co (II) sites efficiently activated Oβ. Within 5 min, FeCo1/3-BDC achieved a 98 % reduction in Rhodamine-B (RhB), surpassing Fe-BDC by a factor of 76 and homogeneous Fenton catalytic systems (Co (II)/peroxymonosulfate (PMS) and Fe (III)/Co (II)/PMS). This work provides a profound understanding of interface electron reconstruction, offering valuable insights into guiding Fenton-like mechanisms.

Acoustic black hole immersed sonoreactor for high-efficiency cavitation treatment

Developing innovative sonoreactors to enhance acoustic processing efficiency holds immense importance in the field of sonochemistry. Traditional immersed sonoreactors (TISs) mainly produce cavitation at the probe tip, with a relatively weak cavitation around the probe, resulting in posing challenges for high-efficiency cavitation treatment. Here we propose an acoustic black hole immersed sonoreactor (ABHIS) in longitudinal-flexural coupled vibration, enabling high-efficiency cavitation treatment by unleashing the cavitation potential of the probe. The symmetrical structure of the probe is altered to introduce a coupling of flexural vibration mode, and an acoustic black hole (ABH) profile is integrated to further enhance both flexural wave number and amplitude. In this paper, we present a systematic theoretical design method for ABHIS and compare its performance with TIS using finite element method (FEM). An ABHIS prototype is fabricated and subjected to experimental tests and cavitation observation. The results demonstrate that our theoretical analysis model accurately predicts the frequency characteristics of ABHIS. The proposed ABHIS exhibits satisfactory dynamic characteristics, with significantly increased vibration displacement and acoustic radiation ability compared to TIS. Importantly, the ABH design significantly expands ultrasonic cavitation regions and enhances acoustic radiation intensity of ABHIS, resulting in a substantial improvement in acoustic processing efficiency.

Membrane modification in enhancement of virus removal: A critical review

Many waterborne diseases are related with viruses, and COVID-19 worldwide has raised the concern of virus security in water into the public horizon. Compared to other conventional water treatment processes, membrane technology can achieve satisfactory virus removal with fewer chemicals, and prevent the outbreaks of viruses to a maximal extent. Researchers developed new modification methods to improve membrane performance. This review focused on the membrane modifications that enhance the performance in virus removal. The characteristics of viruses and their removal by membrane filtration were briefly generalized, and membrane modifications were systematically discussed through different virus removal mechanisms, including size exclusion, hydrophilic and hydrophobic interactions, electronic interactions, and inactivation. Advanced functional materials for membrane modification were summarized based on their nature. Furthermore, it is suggested that membranes should be enhanced through different mechanisms mainly based on their ranks of pore size. The current review provided theoretical support regarding membrane modifications in the enhancement of virus removal and avenues for practical application.

Epitaxial Growth of Multicolor Lanthanide MOFs by Ultrasound for Photonic Barcodes

Epitaxially grown lanthanide metal-organic frameworks (Ln MOFs) exhibit multicolor and characteristic Ln emission with sharp emission bands, which are of great value in the field of information security and anti-counterfeiting. Epitaxial growth of Ln MOFs is generally achieved by solvothermal or hydrothermal methods, which suffer from challenges such as high reaction temperature and long growth time. Here, we report the fast epitaxial growth of multicolor lanthanide MOFs by an ultrasonic method at room temperature. The TbSmSQ shows a core-shell type structure with the Tb ion in the core and Sm in the shell within one crystal and exhibits the characteristic emission lines of Tb and Sm, respectively. The nonporous structure and large distance between lanthanide ions effectively avoid the influence of solvent vapor on the intensity and color of luminescence emission. Its application as photonic barcodes has been studied. This work demonstrates the feasibility of epitaxial growth of multicolor Ln MOFs by the ultrasonic method and its value for anti-counterfeiting and information security applications.

Performance improvement and application of copper-based nanomaterials in membrane technology for water treatment: A review

Membrane fouling, including organic, inorganic, and biological fouling, poses enormous challenges in membrane water treatment. Incorporation of copper-based nanomaterials in polymeric membranes is highly favored due to their exceptional antibacterial properties and capacity to improve membrane hydrophilicity. This review extensively explores the utilization of copper-based nanomaterials in membrane technology for water treatment, with a specific focus on enhancing anti-fouling performance. It elaborates on how copper-based nanomaterials improve the surface properties of membrane materials (such as porosity, hydrophilicity, surface charge, etc.) through physical and chemical processes. It summarizes the properties and potential antibacterial mechanisms of copper-based nanomaterials, primarily by disrupting microbial cell structures through the generation of reactive oxygen species (ROS). Furthermore, recent efforts to enhance the environmental sustainability, cost-effectiveness, and recyclability of copper-based nanomaterials are outlined. The attempts to offer insights for the advancement of anti-fouling practices in water treatment through the use of copper-modified polymer membranes.

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.

β-cyclodextrin modified GO ultrafiltration membranes with enhanced antifouling property for water purification

The study investigated the influence of additives on the fabrication of mixed matrix membranes comprising polyethersulfone (PES), with a specific focus on hydrophilicity, flux, morphology, and antifouling properties. Carboxymethyl modified β-cyclodextrin (CMβ-CD) was used to enhance the dispersion and hydrophilicity of graphene oxide (GO), leading to the formation of a hydrophilic and stable composite nanoparticle (CMCD@GO). The hydrophilicity (WCA <51.5°) and water flux (32.6 L.m-2.h-1) of the modified PES membranes (MCDGO-x) were improved by the incorporation of CMCD@GO nanoparticles, while that of PES membrane was 79.7° and 10.6 L.m-2.h-1. The rate of backscattered light intensity (ΔBS) of MCDGO-x suspensions remains stable, suggesting stable dispersion of CMCD@GO in organic solvents. Compared to the bare PES membrane, the MCDGO-x membrane exhibits a thinner active layer and a finger-like structure. The MCDGO-x membrane exhibited excellent naphthenic acids (NAs) rejection (> 93.2%) due to reduced roughness and higher hydrophilicity, while the GO-modified PES membrane (MGO-5) exhibited lower NAs rejection (87.2%). Furthermore, the MCDGO-5 membrane showed higher flux recovery ratio (FRR) of 79.3% compared to MGO-5 membrane (68.5%) after three cycles, indicating the antifouling performance of MCDGO-x for NAs was significantly improved. The combination of CMβ-CD and GO enhance the flux and antifouling properties of PES ultrafiltration membranes, suggesting significant potential for applications in the purification of oil sands process water and the treatment of oily wastewater.

Functionalization strategies of metal-organic frameworks for biomedical applications and treatment of emerging pollutants: A review

One of the representative coordination polymers, metal-organic frameworks (MOFs) material, is of hotspot interest in the multi field thanks to their unique structural characteristics and properties. As a novel hierarchical structural class, MOFs show diverse topologies, intrinsic behaviors, flexibility, etc. However, bare MOFs have less desirable biofunction, high humid sensitivity and instability in water, restraining their efficiencies in biomedical and environmental applications. Thus, a structural modification is required to address such drawbacks. Herein, we pinpoint new strategies in the synthesis and functionalization of MOFs to meet demanding requirements in in vitro tests, i.e., antibacterial face masks against corona virus infection and in wound healing and nanocarriers for drug delivery in anticancer. Regarding the treatment of wastewater containing emerging pollutants such as POPs, PFAS, and PPCPs, functionalized MOFs showed excellent performance with high efficiency and selectivity. Challenges in toxicity, vast database of clinical trials for biomedical tests and production cost can be still presented. MOFs-based composites can be, however, a bright candidate for reasonable replacement of traditional nanomaterials in biomedical and wastewater treatment applications.

Modulation of defects in metal organic gels to enhance anhydrous proton conduction from subzero to moderate temperature

Exploitation of solid-state proton-conducting materials with high anhydrous proton conductivity from subzero temperature (<273 K) to moderate temperature (>353 K) is a great challenge. Here, Brönsted acid-dopped zirconium-organic xerogels (Zr/BTC-xerogels) are prepared for anhydrous proton conduction from subzero to moderate temperature. Abundant acid sites and strong H-bonding interactions make the CF3SO3H (TMSA)-introduced xerogel gain high proton conductivity from 9.0 × 10-4 S cm-1 (253 K) to 1.40 × 10-2 S cm-1 (363 K) under anhydrous conditions, which are in the leading level. This provides a new possibility to develop wide-operating-temperature conductors.

Enhanced CO2 capture potential of UiO-66-NH2 synthesized by sonochemical method: experimental findings and performance evaluation

The excessive release of greenhouse gases, especially carbon dioxide (CO2) pollution, has resulted in significant environmental problems all over the world. CO2 capture technologies offer a very effective means of combating global warming, climate change, and promoting sustainable economic growth. In this work, UiO-66-NH2 was synthesized by the novel sonochemical method in only one hour. This material was characterized through PXRD, FT-IR, FE-SEM, EDX, BET, and TGA methods. The CO2 capture potential of the presented material was investigated through the analysis of gas isotherms under varying pressure conditions, encompassing both low and high-pressure regions. Remarkably, this adsorbent manifested a notable augmentation in CO2 adsorption capacity (3.2 mmol/g), achieving an approximate enhancement of 0.9 mmol/g, when compared to conventional solvothermal techniques (2.3 mmol/g) at 25 °C and 1 bar. To accurately represent the experimental findings, three isotherm, and kinetic models were used to fit the experimental data in which the Langmuir model and the Elovich model exhibited the best fit with R2 values of 0.999 and 0.981, respectively. Isosteric heat evaluation showed values higher than 80 kJ/mol which indicates chemisorption between the adsorbent surface and the adsorbate. Furthermore, the selectivity of the adsorbent was examined using the Ideal Adsorbed Solution Theory (IAST), which showed a high value of 202 towards CO2 adsorption under simulated flue gas conditions. To evaluate the durability and performance of the material over consecutive adsorption-desorption processes, cyclic tests were conducted. Interestingly, these tests demonstrated only 0.6 mmol/g capacity decrease for sonochemical UiO-66-NH2 throughout 8 consecutive cycles.

Study on acoustic properties of hydrate-bearing sediments with reconstructed CO2 hydrate in different layers during CH4 hydrate mining

Natural gas hydrate (NGH), a clean energy source with huge reserves in nature, and its safe and efficient exploitation fits perfectly with the UN Sustainable Development Goals (SDG-7). However, large-scale NGH decomposition frequently results in subsea landslides, reservoir subsidence, and collapse. In this work, in order to achieve safe and efficient exploitation of NGHs, the stability variation of different reservoir layers by depressurization/intermittent CO2/N2 injection (80:20 mol%, 50:50 mol%) was investigated using acoustic properties (P-wave velocity, elastic modulus), as well as reservoir subsidence under an overburden stress of 10 MPa. The P-wave velocity increased from 1282 m/s to 2778 m/s in the above-reservoir and from 1266 m/s to 2564 m/s in the below-reservoir, significantly increasing reservoir strength after CO2 hydrate formation. The P-wave velocity and elastic modulus in the top reconstructed reservoir were continually decreased by the shear damage of the overlying stress, while they remained stable in the bottom reconstructed reservoir during hydrate mining. However, due to superior pressure-bearing ability of the top CO2 hydrate reservoir, which was lacking in the bottom CO2 hydrate reservoir, the reservoir subsidence was relieved greatly. Despite the stiffness strength of reconstructed reservoir was ensured with CO2/N2 sweeping, the skeletal structure of CH4 hydrate reservoir was destroyed, and only the formation of CO2 hydrate could guarantee the stability of P-wave velocity and elastic modulus which was most beneficial to relieve reservoir subsidence. A large amount of CO2 was used in reservoir reconstruction and CH4 hydrate mining, which achieved the geological storage of CO2 (SDG-13). This work provided a new idea for safe and efficient NGHs mining in the future, and the application of acoustic properties served as a guide for the efficient construction of reconstructed reservoirs and offers credible technical assistance for safe exploitation of NGHs.

Nanofiltration Mixed Matrix Membranes from Cellulose Modified with Zn-Based Metal–Organic Frameworks for the Enhanced Water Treatment from Heavy Metal Ions

Nowadays, nanofiltration is actively used for water softening and disinfection, pre-treatment, nitrate, and color removal, in particular, for heavy metal ions removal from wastewater. In this regard, new, effective materials are required. In the present work, novel sustainable porous membranes from cellulose acetate (CA) and supported membranes consisting of CA porous substrate with a thin dense selective layer from carboxymethyl cellulose (CMC) modified with first-time synthesized Zn-based metal–organic frameworks (Zn(SEB), Zn(BDC)Si, Zn(BIM)) were developed to increase the efficiency of nanofiltration for the removal of heavy metal ions. Zn-based MOFs were characterized by sorption measurements, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The obtained membranes were studied by the spectroscopic (FTIR), standard porosimetry and microscopic (SEM and AFM) methods, and contact angle measurement. The CA porous support was compared with other, prepared in the present work, porous substrates from poly(m-phenylene isophthalamide) and polyacrylonitrile. Membrane performance was tested in the nanofiltration of the model and real mixtures containing heavy metal ions. The improvement of the transport properties of the developed membranes was achieved through Zn-based MOF modification due to their porous structure, hydrophilic properties, and different particle shapes.