ZIF-8 Loading Research Articles

ZIF-8 loaded Ag/ZnO electrospun nanofibers enabling high-performance H2 gas sensing for battery safety early warning

Safety issues triggered by battery thermal runaway have become the most crucial obstacle to the future development of the high-energy-density energy storage systems. As hydrogen (H2) will be inevitably generated along with heat release caused by the side reactions in the early stages of battery thermal runaway, rapid monitoring of trace H2 is considered as an effective measure enabling the battery safety early warning. Herein, to develop high-performance H2 sensing materials to monitor of low-concentration H2 leakage, ZIF-8 loaded Ag/ZnO electrospun nanofibers (ZAZ NFs) were designed by electrospinning and self-sacrificial template methods. Benefiting from all the enrichment and sieving effects of ZIF-8 shell, the catalytic and sensitization effects of Ag and abundant active sites provided by Ag and ZIF-8 loading, the ZAZ sensor enables ppb-level limit of detection toward H2, fast response (9 s), high selectivity and excellent humidity resistance. Furthermore, this ZAZ sensor can also realize the safety early warning (67.79 s before battery bulge) for practical pouch lithium cells, highlighting its great application potential in future advanced battery safety management system.

Flexible and highly-loaded mixed-matrix membrane with bi-continuous metal–organic frameworks transfer pathway for gas separation

Highly-loaded metal–organic frameworks (MOFs) based mixed matrix membranes (MMMs) are essential for high-efficiency gas separation. However, the continuous distribution of MOFs across the membrane with intensified interface remains challenging. Herein, a flexible and defects-free MMM with a bi-continuous MOFs pathway is constructed by dopamine (DA)-assisted MOFs growth along nanofibers. Nanofibers are used to upload and distribute ZIF-8, which continues to grow via an epitaxial growth strategy to obtain ZIF-8 fibers, achieving ZIF-8 continuous both in long and short range. DA promotes heterogeneous nucleation and growth of ZIF-8 on fiber surface by chelating with Zn2+ through –OH and –NH2 groups. DA also ensures excellent interfacial compatibility by hydrogen bonding interaction between amino groups of DA and ether-oxygen groups of PEO. Finally, the highly-loaded MMM is constructed by in-situ photopolymerization of Poly (ethylene glycol) diacrylate) to embrace ZIF-8 fibers tightly. The resultant MMM presents ZIF-8 loading as high as 72.41 vol% with Young’s modulus of 33.42 MPa, and unchanged morphology and separation performances after bending for 180° over 50 times, revealing outstanding mechanical properties. The CO2 permeability and CO2/N2 selectivity are 280.3 % and 73.0 % higher than the PEO membrane, surpassing the 2019 McKeown upper bound.

Gravitational modulation of filler distribution in asymmetric mixed matrix membrane: Achieving high loading in skin layer

The fillers in asymmetric mixed matrix membranes (AMMMs) by phase inversion tend to distribute across the membrane, but less in the skin layer, resulting in limited enhancement of gas separation performance. In this work, an external gravity field is proposed to induce polystyrene-acrylate (PSA) modified hollow ZIF-8 nanospheres (PHZ) to settle and accumulate in the skin layer by the density difference between ZIF-8 and the polymer solution, then through phase inversion, the gravity induced AMMMs (GAMMMs) with improved ZIF-8 loading in skin layer is constructed. This is confirmed by the EDS analysis of the membrane cross-sections that more PHZ settle and accumulate in the skin layer, which enhances the filler loading by 330 % in comparison to the AMMMs without gravity sedimentation. Together with the hollow cavity of PHZ, the gas permeation can be improved greatly. Meanwhile, the PHZ can also guarantee the favorable interfacial compatibility by the hydrogen bonding interaction between the carboxyl groups in PSA with the PES polymer matrix, which is demonstrated by the slightly elevated Tg of GAMMMs over the ZIF-8/PES membrane. Consequently, the PHZ/PES GAMMMs can achieve high gas permeation while keeping sufficient selectivity at high filler loading in the skin layer. The PHZ-8d/PES GAMMM shows H2 permeance of 29.11 GPU and H2/CH4 of 83.04, which are 142.85 % and 5.99 % higher than those of ZIF-8/PES AMMM without gravity sedimentation, and exceeding the corresponding 2008 Robeson upper bound. This proposed GAMMM shows a great potential in the large-scale MMMs based gas separation.

Synthesis of ZIF-8/PVA microspheres with the assistance of a microfluidic device and their controlled drug release properties

ZIF-8/PVA microspheres with an even size were synthesized with the assistance of a simple microfluidic device. The ZIF-8/PVA microdroplets were first generated in a simple co-flow microfluidic device using a PVA aqueous solution dispersed with ZIF-8 nanoparticles as the dispersed phase and fatty acid methyl ester (FAME) as the continuous phase. Subsequently, the ZIF-8/PVA microdroplets were further extracted to form ZIF-8/PVA microspheres. The influence of the type of continuous phase on the sphericity of microspheres was investigated and the effect of ZIF-8 content was studied. Further studies showed that decreasing the extraction rate and using additives of NaCl in the dispersed phase could improve the sphericity of the ZIF-8/PVA microspheres. Finally, the synthesized ZIF-8/PVA microspheres were used to study the loading and release of tetracycline. The results showed that the loading of ZIF-8/PVA microspheres was more than 5 times higher than that of pure PVA microspheres. The drug release time of ZIF-8/PVA microspheres was much longer than that of the PVA microspheres and the release rate was significantly affected by the pH of the environment.

Facile preparation of thin and nanodisperse ZIF-8/PDMDES hybrid membrane for efficient alcohol recovery via pervaporation

Membrane-based separation technology has emerged as a focal point of research in the realm of renewable energy. In this investigation, nano-sized ZIF-8 particles were synthesized and then embedded into a poly-dimethyldiethoxysilane (PDMDES) matrix through a facile method, thereby creating an ultra-thin ZIF-8/PDMDES hybrid membrane specifically designed for alcohol permselective pervaporation. The successful synthesis of ZIF-8 nanoparticles was corroborated by the XRD, SEM, and FTIR characterization approaches. The addition of ZIF-8 nanoparticles into the hybrid membranes markedly augmented their hydrophobicity, thermal stability, and affinity toward alcohols, surpassing the attributes of the unmodified PDMDES membrane. The utilization of low-viscosity PDMDES led to an actual ZIF-8 loading that exceeded the theoretical one, resulting in unique membrane morphologies: dense layer and loosely-packed layer. The newly prepared hybrid membrane exhibited an improved separation factor and simultaneously increased permeation flux in the alcohol recovery via pervaporation, showcasing preferable anti-tradeoff achievements. Accordingly, the obtained hybrid membrane with a ZIF-8 loading of 6.5 wt% displayed an outstanding pervaporation performance for recovering ethanol from a 5 wt% ethanol/water mixture at 40 ℃, achieving a remarkable total flux of 6.67 kg∙m−2h−1, a distinguished ethanol permeability of 14.36 × 104 Barrer, and a competitive separation factor of 7.68.

Simultaneously improved H+ conductivity and H+/V4+ selectivity for all vanadium flow battery by ZIF-8 induced physical cross-linking

One of the major challenges in all vanadium redox flow battery (VRFB) is the trade-off between proton conductivity and vanadium ion cross-mixing. Here, we simultaneously enhanced proton conductivity and sharply reduced the vanadium crossover by introducing ZIF-8 into a sulfonated polyimide (6FTMA-100) to prepared a high performance VRFB membrane. Compared with the pristine membrane, the proton conductivity increased from 34.6 to 47.4 mS cm−1, and the vanadium ion permeation rates decreased from 3.56 × 10−7 to 0.82–1.88 × 10−7 cm2 min−1 with different ZIF-8 doping concentrations. The ZIF-8 doped membranes also showed increased viscosity, reduced membrane swelling ratio and increased Young's modulus. We propose this is due to the strong hydrogen bonding (−106.68 Kcal/mol) between the N in imidazole group and H in -SO3H. Battery performance confirmed that the optimized MMM-2 (2 % ZIF-8 loading) displayed the energy efficiency of 80 % at 160 mA cm−2 that much higher than its pristine 6FTMA-100, N117, and most of the reported sulfonated polyimides. This idea of creating physical crosslinked network provided an efficient way for achieving highly efficient VRFB membranes.

Intricacies of CO2 removal from mixed gases and biogas using polysulfone/ZIF-8 mixed matrix membranes - part 1: experimental.

In this work, we explore the potential of polysulfone/ZIF-8 mixed matrix membranes (MMMs) for the enrichment of biogas to biomethane. To this end, we present data for these MMMs on permeability and selectivity as function of pressure and feed composition, at different loadings of ZIF-8. Specifically, we study dense polysulfone membranes prepared by solvent evaporation, with a ZIF-8 loading in the range 0.5-5 wt% for separation of CO2 from artificial mixtures of CO2 and CH4, and also biogas from an operating plant. The MMMs with 1 wt% filler loading gave the highest enhancement in permeability and selectivity, of 56.8% and 41% respectively, as compared to pure PSF membranes. At higher loadings, a tendency for the ZIF-8 particles to agglomerate was seen, which may compromise the ability of the filler to improve membrane performance. With mixed gases, increases in CO2 permeability of about 8 to 34% were observed depending on the gas composition, the enhancement being the higher, the lower the CO2 content. For biogas, permeability and selectivity of the 1% ZIF-8 loaded MMMs were found to be 14.6% and 39.64% lesser respectively than the pure gas values. The study thus throws light on the differences in membrane performance with mixtures as compared to ideal values obtained with pure gases and hence underlines the importance of lab-scale testing of the membranes with actual gas mixtures in the intended applications.

Loading and thermal behaviour of ZIF-8 metal-organic framework-inorganic glass composites.

Here we describe the synthesis of a compositional series of metal-organic framework crystalline-inorganic glass composites (MOF-CIGCs) containing ZIF-8 and an inorganic phosphate glass, 20Na2O-10NaCl-70P2O5, to expand the library of host matrices for metal-organic frameworks. By careful selection of the inorganic glass component, a relatively high loading of ZIF-8 (70 wt%) was achieved, which is the active component of the composite. A Zn⋯O-P interfacial bond, previously identified in similar composites/hybrid blends, was suggested by analysis of the total scattering pair distribution function data. Additionally, CO2 and N2 sorption and variable-temperature PXRD experiments were performed to assess the composites' properties.

A multifunctional chitosan based porous membrane for pH-responsive antibacterial activity and promotion of infected wound healing.

Unsatisfactory mechanical and antibacterial properties restricted the solo use of chitosan (CS) as a wound dressing. In this work, a novel CS/hydroxyapatite/ZIF-8 (CS/HAp/ZIF-8, CHZ-10) porous membrane was facilely constructed by in situ loading of ZIF-8 on CS/HAp. The advantages of the three compositions were rationally integrated, and the multifunctionality and practicality of this CS-based dressing were improved. HAp not only improved the mechanical strength and stability of CS, but also promoted cell proliferation and accelerated hemostasis with its released Ca2+. Meanwhile, ZIF-8 enhanced the antibacterial activity of CS by releasing antibacterial Zn2+ in a pH-responsive and sustainable manner, avoiding the bio-accumulation toxicity of heavy metals. Compared with CS/HAp and conventionally used gauze, CHZ-10 exhibited superior coagulation and hemolytic ability, as well as outstanding antibacterial activity against E. coli and S. aureus. Besides, both in vivo observation and histological evaluation demonstrated that CHZ-10 could not only effectively inhibit bacterial infection and reduce inflammation of the wound, but also promote its re-epithelialization, granulation, tissue formation and collagen fibre growth, leading to effectively enhanced wound-healing. This work provides a new method for the easy construction of multifunctional antibacterial dressings based on CS, showing promise for application in clinical wound care.

Polyacrylonitrile ultrafiltration membranes incorporating graphene oxide fillers modified with Zeolitic Imidazolate Framework-8 and 3-aminopropyltriethoxysilane for dye and salt removal in real textile wastewater

Chemical grafting of graphene oxide (GO) with 3-aminopropyltriethoxysilane (APTES) reduced GO-sheet aggregation, improved their dispersion and interaction with the polymer matrix. Zeolitic Imidazolate Framework (0.1–1.5 wt%) were grown on GO-APTES forming ZIF-8 @GO-APTES nanocomposites. The incorporation of these composites into polyacrylonitrile (PAN) ultrafiltration (UF) membranes resulted in increased hydrophilicity (contact angle decreasing from 69.5° to 25.9°), and pure water flux (increasing from 31.3 L.m-2 h−1 to 101.3 L.m-2 h−1). The dye rejection in synthetic and colour removal in real textile wastewater increased in the composite membranes. Methyl orange rejection increased from 61 % to above 75 % whilst for methylene blue it increased from 33 % to 40 %. Colour removal in real textile wastewater increased with the increasing loading of ZIF-8 @GO-APTES in the membranes, increasing from 63 % for PAN membrane to 96 % in the composite membrane with high loading of ZIF-8 @GO-APTES. Relatively high metal ions (Pb, Zn, Ca, Cr, and Mg) rejection was also observed, increasing from 40 % in PAN and GO@PAN membranes to between 60 % and 80 % as filler content was increased. The difference in solute rejection with filler loading was attributed to electrostatic interactions due the presence of the functional nanocomposites embedded in the membrane surface layer. The rejection fractionally increased as the ZIF-8 component in the filler increased within the same series and generally more as the overall loading of ZIF-8 @GO-APTES in the PAN membranes was increased, further confirmation the electrostatic-based rejection mechanism. The ZIF-8 @GO-APTES/PAN membranes showed high antifouling properties with FRR of 93.4 % compared to 43.5 % for pristine PAN membranes.

ZIF-8-based dual layer hollow fiber mixed matrix membrane for natural gas purification

To prevent pipe damage and lower operating costs, natural gas must be cleaned of pollutants like carbon dioxide (CO2) and hydrogen sulphide (H2S). High selectivity of the functional material in the mixed matrix membranes (MMMs) allows for a more efficient gas separation compared to traditional polymeric membranes. However, poor dispersion and compatibility between the functional material and the polymer matrix become one of the major problems of MMMs. The use of zeolite imidazole (ZIF-8) in MMMs has been explored for its ability to separate CO2/CH4 due to its versatile gas molecule diameter range and effective CO2 adsorption. In this study, the effects of ZIF-8 at various loadings were examined on the physical and chemical properties of dual layer hollow fiber MMMs and gas separation efficiency. Following the successful production of 86.25 nm ZIF-8 nanoparticles, ZIF-8-based DLHF MMMs were created. The results showed that 0.5 wt% ZIF-8 loading provided the best results, with excellent interaction between the polymer PSf and the inorganic filler ZIF-8, strong heat resistance, and chemical stability. Increased CO2 permeability and CO2/CH4 ideal selectivity by 72.5 % and 1196.2 % respectively, compared to the unmodified membrane. It was inferred through this study that minimal loading of 0.5 wt% ZIF-8 in the DLHF MMMs improved their ability to separate gases, making them a good option for capturing CO2.

Study on water and gas permeation characteristics with ZIF-8 mixed matrix membranes

Abstract The membrane separation process lacks intrinsic permeation characteristics to compete with other separation technologies like adsorption, sedimentation, coagulation, skimming, and distillation. A mixed matrix membrane (MMM) is one of the strategies to improve the separation characteristics with embedded nanofillers particles. Zeolite imidazolate framework (ZIF) has a new subclass of inorganic–organic hybrid materials that are being introduced as new fillers for incorporation into the polymer matrix for various applications such as oily wastewater separation, wastewater treatment, natural gas dehydration, landfill gas upgrading, and mixed gas separation. In this experimental work, a metal-organic framework called ZIF-8 was synthesized and used as a filler for modification of MMMs and characterized with FTIR and SEM. ZIF-8 nanoparticles up to 5 wt% loading were added to PSF casting solution then the permeation characteristics of MMMs showed an improved result like the pure water flux of the modified membrane at 2.5 bar was increased up to 456.38 L/m2h. In the case of pure gas separation, at 5 wt% ZIF-8 loading in PSF, the pure gas CO2 permeability at 9 bar pressure had increased to 10.54 barrer.

Facile and green lyocell/feather nonwovens with in-situ growth of ZIF-8 as adsorbent for physicochemical CO2 capture

Carbon dioxide (CO2) removal based on porous materials adsorption is one of the most promising strategies to address current global climate change issues. However, existing porous materials suffer from several problems including weak interfacial connection between functional nanomaterials and substrates, not being eco-friendly, poor processability, short service life, and expensive manufacturing cost. Herein, we report a green fiber-based CO2 adsorbent through in-situ growth of ZIF-8 on 3D fibrillar lyocell/feather nonwovens (ZIF-8@LFNW) in a low-cost and scalable manner. The combination of fibrillation treatment with de-crosslink strategy endows lyocell/feather nonwovens with the coexisting structure of micro-nano fibers and abundant functional groups such as hydroxyl, carboxyl group, and amino group, which greatly increases ZIF-8 loading. Moreover, with the synergistic effect of ZIF-8 and amino groups in feather fibers, the resultant ZIF-8@LFNW achieved both physical and chemical capturing of CO2. Notably, ZIF-8@LFNW with the loading rate of 12.41 wt% possessed optimal CO2 adsorption capacity of 4.46 cm3 g−1 at a high CO2 concentration environment and 190.84 ppm g−1 at a low CO2 concentration environment whilst exhibiting stable cyclic adsorption/desorption behavior. Taken together, this work paves the way for designing high-performance environmentally friendly fiber-based CO2 adsorbents.

Rapid Fabrication of High‐Permeability Mixed Matrix Membranes at Mild Condition for CO2 Capture (Small 19/2023)

Gas Separation Membranes In article number 2208177, Ming-Jie Yin, Quan-Fu An, and co-workers propose a “confined swelling coupled solvent controlled crystallization” strategy to rapid preparation of mixed matrix membrane for CO2 capture. The fabricated membrane exhibits 4-fold enhancement in CO2 permeability, benefiting from the high ZIF-8 loading creating additional speedy mass transfer channel for gas transport.

Highly propylene-selective asymmetric mixed-matrix membranes by polymer phase-inversion in sync with in-situ ZIF-8 formation

Although mixed-matrix membranes (MMMs) have been extensively studied, their commercial applications have been hampered by scientific and engineering challenges. Herein, we report an innovative one-step MMM fabrication method that can put the commercialization of MMMs forward by overcoming most of the current challenges because it enables the rapid formation of high-performance asymmetric MMMs in a scalable manner. The method termed phase-inversion in sync with metal–organic framework (MOF) formation (PIMOF) involves a polymer film undergoing phase inversion and simultaneously ZIF-8 nanoparticles forming in-situ inside the polymer. The resulting MMMs show unexpectedly high C3H6/C3H8 separation performances (C3H6 permeance of ca. 7.5 GPU and C3H6/C3H8 separation factor of ca. 107), which is attributed mostly to the high effective ZIF-8 loading (>50 wt%) and the enhanced molecular sieving effect of the unusually small sub-5 nm ZIF-8 filler nanoparticles by restricted linker motion.

Piperine loaded metal organic frameworks reverse doxorubicin induced chemobrain in adult zebrafish.

The study's primary goal was to enhance medicinal potential of piperine (PIP)-loaded zeolitic imidazolate frameworks-8 (PIP@ZIF-8) against doxorubicin (DOX)-induced cognitive impairments in zebrafish. Herein, PIP@ZIF-8 was synthesized via easy, economical and reproducible ultrasonication method followed by spray drying technology. ZIF-8's structural integrity has been confirmed by PXRD, and even after PIP was encapsulated, the structure of ZIF-8 remained unchanged. Pure ZIF-8 and PIP@ZIF-8 were subjected to TEM analysis, which revealed hexagonal morphology with a nanosize range. FTIR and UV-Visible spectroscopy studies confirmed the drug loading of ZIF-8. Studies on in vitro release revealed 71.48±7.21% and 34.56±5.35% PIP release from PIP@ZIF-8 and unformulated PIP, respectively in pH7.4. The highest antioxidant scavenging results were obtained with vitamin C (73.77±6.7%) at an intensity of 200μg/ml, though it was 65.09±2.5% and 57.99±3.1% for PIP@ZIF-8 and PIP, respectively. In vivo studies on zebrafish showed that DOX administration remarkably impaired cognitive activity in T-Maze, and downregulated spatial memory and locomotor activity in the open field test. In addition, DOX administration caused a downregulation in GSH and SOD levels and increase in LPO, AChE and TNF-α levels compared to the vehicle group along with changes in brain histopathology. Further, PIP@ZIF-8 reversed the DOX-induced cognitive impairments by its antioxidant and neuroprotective properties. It can be concluded that PIP@ZIF-8 has a promising therapeutic potential against the chemotherapy-induced cognitive impairments in zebrafish.

A new ternary Pebax®1657/maltitol/ZIF-8 mixed matrix membrane for efficient CO2 separation

In this study, a novel high-performance mixed matrix membrane (MMM) based on poly(ether-b-amide) was fabricated in which the synthesized ZIF-8 nanoparticles embedded into a maltitol-modified Pebax®1657. Maltitol (as an inexpensive low molecular weight additive) provides a good CO2 affinity. Moreover, an existence of selective affinity in ZIF-8 nanoparticles toward CO2, enhances the CO2 permeability and its selectivity over other penetrants. The synthesized ZIF-8 nanoparticles were added (0–10 wt%) into the Pebax/maltitol (20 wt%) matrix to prepare the Pebax/maltitol/ZIF-8 MMMs. Field Emission Scanning electron microscopy (FESEM) was applied to evaluate the MMM morphology, where excellent dispersion was shown. Thermogravimetric analysis (TGA) was used to determine the thermal properties of prepared membranes. The TGA results indicated that the decomposition temperature of membranes raised as the ZIF-8 loading increased within the Pebax matrix. Differential scanning calorimetry (DSC) implied the disruptive role of MOF on polymer chain mobility which reduces the overall crystallinity and increases the glass transition temperature of MMMs. The analysis of gas permeability at 30 °C and 10 bar revealed that Pebax/maltitol (20 wt%)/ZIF-8 (10 wt%) membrane showed the highest CO2 permeability of 429.57 Barrer. In addition, the highest selectivity values of 69.31 and 26.59 for CO2/N2 and CO2/CH4 separation, respectively; obtained by Pebax/maltitol (20 wt%)/ZIF-8 (5 wt%) at 30 °C and 10 bar. Finally, the performance of Pebax/maltitol (20 wt%)/ZIF-8 (5 wt%) membrane was able to surpass the Robeson upper bound for the CO2/N2 separation and Robeson prior bound for CO2/CH4 one.

The assembly of polysaccharide ZIF-8-based foam for efficient adsorptive removal of PEDCs from environmental water

ZIF-8 is a type of porous coordination metal-organic frameworks (MOFs) material with excellent adsorption properties. However, the inevitable acid-base sensitivity and low plasticity of ZIF-8 impede its application to the field of compound adsorption and separation. Here, a novel reusable monolithic MOFs foam material, polysaccharides (CMC & chitin) gels zeolitic imidazolate frameworks (PC-ZIF-8), has been developed to effectively adsorb five Phenolic Endocrine Disrupting Chemicals (PEDCs) from environmental water. In this study, the forming strategy of a continuous phase change sol-gel MOFs material was designed. The carboxymethyl cellulose and chitin hydrosol were used as the self-assembly medium for in-situ synthesizing sol-type MOFs by a one-step method. Several favorable characteristics of PC-ZIF-8 have been confirmed, including large surface area (619.47 m2/g), low density (<0.085 g/cm3), high ZIF-8 loading rate (>80%, wt%), high structural strength, high acid, and alkali tolerance, and easy recyclability. The adsorption efficiency of PC-ZIF-8 for 5 BPs in water is 92.97%− 99.12%, and the maximum adsorption capacity is 120.1–172.9 mg/g. After simple regeneration treatment, PC-ZIF-8 has been recycled 5 times, and the overall recovery rate still remains above 80.0%. The results of this study indicate that PC-ZIF-8 is a reliable adsorbent for BPs in environmental water purification.

Enhancement of H2 Separation Performance in Ring-Opened Tröger’s Base Incorporating Modified MOFs

Energy-efficient hydrogen (H2) recovery technology is of great significance to developing H2-based economy and accomplishing global carbon-neutrality with minimized worldwide energy consumption. A ring-opened Tröger’s base (TBOR) polymer membrane as a highly H2-selective membrane holds great promise for recovering H2 while partial microporosity loss induced by ring opening reaction deteriorates the H2 permeability across the pure membrane. Herein we introduce polydopamine-modified ZIF-8 (PDA-ZIF-8) nanoparticles into TBOR to develop a permeable membrane for selective H2 separation. The resultant mixed matrix membranes demonstrate the significantly improved H2 permeability, owing to the porous structure of ZIF-8, and efficiently exclude large molecules of CH4 and N2, giving rise to promising H2/CH4 and H2/N2 ideal selectivities. The PDA-ZIF-8 interacts with the secondary amines of TBOR via hydrogen bonds, creating good interfacial adhesion, thus preventing a sharp selectivity loss that occurred in most mixed matrix membranes upon increasing filler loadings. At a maximum ZIF-8 loading of 50 wt %, the pure H2 permeability is 457 Barrer, increasing to 4.2 times as compared with the undoped membrane, and the ideal H2/CH4 selectivity of 57 and ideal H2/N2 selectivity of 59 are achieved. The H2/CH4 separation properties remain unchanged upon increasing feed pressures, indicating the membrane’s good stability when operated at realistic high pressures. The ring-opening functionalization of Tröger’s base has proven to be very useful for fabricating selective mixed matrix membranes and can be extended for designing H2-selective hybrid membranes with other porous fillers.

MOF-derived nanocomposites functionalized carbon molecular sieve membrane for enhanced ethylene/ethane separation

Fine tailoring the pore structure and sorption capability of carbon molecular sieve (CMS) membrane is highly desirable for efficient separation of C2H4/C2H6 gas pair. In this work, a facile approach was proposed to enrich the ultramicroporosity of CMS membrane and enhance the affinity adsorption capacity for C2H4, in which ZIF-8 nanoparticles were incorporated into a novel precursor polymer of phenolphthalein-based poly (arylene ether ketone) (PEK-C) followed by carbonization to prepare mixed matrix CMS membranes to achieve simultaneously high C2H4 permeability and high C2H4/C2H6 selectivity. The ZIF-8-derived nanocomposites partially maintain the pore structure of ZIF-8 precursor, and have good compatibility with the carbon matrix. The BET surface areas, micropore volume and the number of ultramicropore with molecular sieving ability of CMS membrane are greatly improved due to the introduction of ZIF-8-derived microporous carbons, resulting in a significant increase in the C2H4 permeability and C2H4/C2H6 diffusion selectivity. The C2H4/C2H6 sorption selectivity of CMS membrane is also enhanced owing to the selective adsorption affinity of the ZIF-8-derived Zn2+ metal oxides for C2H4. The C2H4 permeability of mixed matrix CMS membrane with 10 wt% ZIF-8 loading is increased by 42% compared to that of neat CMS membrane, and the C2H4/C2H6 selectivity is increased by 102%.