•High C3H6/C3H8 separation performance ZIF-8/PVAc mixed matrix membranes were prepared.•Both the C3H6 permeability and C3H6/C3H8 selectivity are about 10-fold increase over pure PVAc.•The mechanical ...strength and plasticization resistance of the neat polymer membrane was also improved.•The favorable interfacial interaction between ZIF-8 and PVAc was verified by several techniques.•The gas transportation mechanism through ZIF-8/PVAc MMMs was also evaluated.
The implementation of membrane-based separation for olefin/paraffin mixtures has the potential to significantly reduce energy consumption, but is limited by the lack of suitable membrane materials with desired performance and low cost. Here, mixed matrix membranes (MMMs) fabricated from incorporating ZIF-8 nanocrystals into the poly(vinyl acetate) (PVAc) matrix exhibit significant improvement of propylene/propane permeability and selectivity as well as the operating stability. On the 39 wt% ZIF-8/PVAc MMMs, both the C3H6 permeability and C3H6/C3H8 selectivity are about 10-fold increase over pure PVAc. The gas transportation mechanism through ZIF-8/PVAc MMMs was also evaluated. The favorable interfacial interaction between the H of the imidazole in the ZIF-8 and ester groups of PVAc enhances the mechanical strength and plasticization resistance of the neat polymer membrane. Therefore, the newly developed composite membrane may have great potential for industrial C3H6/C3H8 separation.
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•A novel noble-metal-free Mo2C-In2S3 photocatalyst was synthesized by hydrothermal method.•Mo2C facilitates the separation of charge carriers and extends the visible light absorption ...of In2S3.•The H2 generation rate of the optimal Mo2C-In2S3 composite was 25.8 times higher than In2S3-1% Pt.•The possible photocatalytic hydrogen production mechanism was discussed.
Currently, designing novel noble-metal-free photocatalysts with efficient carriers migration and catalytically active sites have been a researching hotspot in photocatalytic hydrogen evolution. In this paper, a novel noble-metal-free Mo2C-In2S3 heterojunction was synthesized by a simple hydrothermal method. Morphology characterization revealed In2S3 was attached to Mo2C. Electrochemical results showed Mo2C improved the interface conductivity, and promoted the transportation of photogenerated carriers. Under visible light, the optimal Mo2C-In2S3 composite achieved a H2 generation rate of 535.58 μmol h−1 g−1, which was 175.6 and 25.8 times higher than pristine In2S3 (3.05 μmol h−1 g−1) and In2S3-1% Pt (20.73 μmol h−1 g−1). In addition, a reasonable mechanism of the elevated photocatalytic activity was also discussed. This study demonstrates commercial Mo2C has an important effect of separating carriers and replacing Pt as co-catalyst in heterojunctions. This research also provides a method to design and synthesize new noble-metal-free photocatalysts for excellent hydrogen production activity.
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•PEN/GO-PDA hierarchically structured nanofibrous membrane was fabricated.•The membrane exhibited fast flux of 99.7L/m2h and high rejection (99.8%).•The membrane showed high ...mechanical strength and temperature resistance.•The membrane exhibited excellent antifouling property and reusability.
Development of efficient and durable nanofibrous composite membranes for dyes separation is still a big challenge in the practical applications. Herein, we demonstrated a novel nanofibrous composite membrane consisting of electrospun poly(arylene ether nitrile)(PEN) nanofibrous substrate and bioinspired polydopamine (PDA) coated graphene oxide barrier layer for anionic dyes separation. To achieve this target, PEN nanofibrous mat was prepared by electrospinning technique and hot-pressing treatment. Thereafter, the graphene oxide nanosheets were directly assembled onto above highly porous PEN nanofibrous mat by a simple vacuum suction method. Finally, as-obtained PEN/GO nanofibrous composite membrane was further modified by bioinspired PDA coating, thus forming PEN/GO-PDA nanofibrous composite membrane. Benefiting from the superiority of hydrophilic GO-PDA skin layer and interconnected porous PEN nanofibrous supporting layer, the resultant optimized PEN/GO-PDA nanofibrous composite membrane exhibited an excellent permeate flux of 99.7L/m2h (0.1MPa, pH=3.0) and a high rejection (99.8%) for Direct Blue 14 with the concentration of 100mg/L at 25°C. This novel composite membrane demonstrated excellent mechanical strength of 28.1MPa and achieved high temperature resistance. The rejection of Direct Blue 14 (100mg/L) remained 92.6% and permeate flux reached 141.5L/m2h as the operating temperature increased to 90°C. Moreover, the resultant PEN/GO-PDA nanofibrous composite membrane exhibited good reusability after repeated operations and excellent antifouling properties (the flux recovery ratio reached 95.0% after 3 runs for 9h). This work provides an alternative way to prepare high-performance composite membrane materials, which can deal with multiple challenges for dyes separation.
Kinetic‐quantum‐sieving‐assisted H2:D2 separation in flexible porous materials is more effective than the currently used energy‐intensive cryogenic distillation and girdle‐sulfide processes for ...isotope separation. It is believed that material flexibility results in a pore‐breathing phenomenon under the influence of external stimuli, which helps in adjusting the pore size and gives rise to the optimum quantum‐sieving phenomenon at each stage of gas separation. However, only a few studies have investigated kinetic‐quantum‐sieving‐assisted isotope separation using flexible porous materials. In addition, no reports are available on the microscopic observation of isotopic molecular transportation during the separation process under dynamic transition. Here, the experimental observation of a significantly faster diffusion of deuterium than hydrogen in a flexible pore structure, even at high temperatures, through quasi‐elastic neutron scattering, is reported. Unlike rigid structures, the extracted diffusion dynamics of hydrogen isotopes within flexible frameworks show that the diffusion difference between the isotopes increases with an increase in temperature. Owing to this unique inverse trend, a new strategy is suggested for achieving higher operating temperatures for efficient isotope separation utilizing a flexible metal–organic framework system.
An experimental observation of hydrogen isotope diffusion in flexible MIL‐53(Al) is demonstrated through quasielastic neutron scattering. Unlike rigid structures, the diffusion difference between the isotopes in the flexible MIL‐53(Al) increases with an increase in temperature. Owing to this unique inverse trend, a new strategy is suggested for achieving higher operating temperatures for efficient isotope separation utilizing a flexible metal–organic framework (MOF) system.
Electrospun polyvinylidene fluoride-co-hexafluoropropylene (PVDF–HFP) nanofibers have been modified with cellulose regenerated from ionic liquid solution. Three-dimensional impregnation of cellulose ...provides greater control over porosity, pore size, wettability as well as the mechanical and thermal properties of the electrospun membrane. Formation of smaller pores with narrower pore size distribution is achieved as the fibers are coated with cellulose matrix. At 15wt.% cellulose, the mechanical properties of electrospun PVDF–HFP are enhanced as the elastic modulus increases from 17MPa to 54MPa and the tensile strength also improves from 5.5MPa to 8.6MPa. The resulting membrane exhibits superhydrophilicity and underwater supoeroleophobicity and is successfully applied for selective separation of water from oil with efficiencies up to 99.98%.
•Modification of electrospun PVDF–HFP membrane by 3D cellulose penetration•Hydrophobic membrane becomes superhydrophilic with enhanced mechanical behavior.•Cellulose provides control over membrane pore size, porosity and wettability.•Composite membrane is used for oil–water separation with high efficiency.
Receptors. In their Communication (e202216011), Jan J. Weigand et al. report the selective separation of lithium, magnesium, and calcium using 4‐phosphoryl pyrazolones as pH‐regulated receptors.
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•PF6-based Ionic liquid membrane has been impregnated in polysulfone membrane.•A composite ionic liquid-based polysulfone membrane has been fabricated.•The composite membrane has been ...used for selective Li separation from brine.•Ultrasonic propagation has been used as deriving force in the separation process.
Battery industry, one of the most crucial components of the modern world, relies heavily on lithium production, and brines from the spent battery materials is one of the most important sources to exploit lithium. A new ultrasonic assisted membrane processing is proposed for lithium separation simulated brine. The effects of membrane composition, feed concentration, and ultrasonic conditions on the lithium extraction efficiency have been explored. The composite membrane including polysulfone (PSF) as the support and 1-alkyl-3-methylimidazolium hexafluorophosphate and tributyl phosphate as ionic liquid membrane. A porous PVC membrane has been used for prevention of the ILM loss. The optimal ultrasonic frequency is approximately 250 kHz, which matches the bulk modulus of the membrane and enhances the separation efficiency. Higher frequencies and optimized amplitude and pulse cycle settings further improve the lithium flux and selectivity. Moreover, higher flux and selectivity are achieved when separating lithium from alkali metal chlorides at higher feed concentrations, ranging from 250 ppm to 1000 ppm. The mechanism of enhanced lithium extraction by ultrasonics is attributed to the combination of microbubble formation, cavitation, and heat generation, which disrupt the concentration gradient and facilitate lithium transport across the membrane.
Genes specifying long non-coding RNAs (lncRNAs) occupy a large fraction of the genomes of complex organisms. The term 'lncRNAs' encompasses RNA polymerase I (Pol I), Pol II and Pol III transcribed ...RNAs, and RNAs from processed introns. The various functions of lncRNAs and their many isoforms and interleaved relationships with other genes make lncRNA classification and annotation difficult. Most lncRNAs evolve more rapidly than protein-coding sequences, are cell type specific and regulate many aspects of cell differentiation and development and other physiological processes. Many lncRNAs associate with chromatin-modifying complexes, are transcribed from enhancers and nucleate phase separation of nuclear condensates and domains, indicating an intimate link between lncRNA expression and the spatial control of gene expression during development. lncRNAs also have important roles in the cytoplasm and beyond, including in the regulation of translation, metabolism and signalling. lncRNAs often have a modular structure and are rich in repeats, which are increasingly being shown to be relevant to their function. In this Consensus Statement, we address the definition and nomenclature of lncRNAs and their conservation, expression, phenotypic visibility, structure and functions. We also discuss research challenges and provide recommendations to advance the understanding of the roles of lncRNAs in development, cell biology and disease.
Physical aging of polymer of intrinsic microporosity PIM-1 is one of the major obstacles for its application as a commercial membrane material for gas separation. In this work, physical aging of ...PIM-1 and matrices of this same polymer containing graphene-like materials were studied. Graphene-like fillers resulted from the functionalization of graphene oxide (GO) with two alkyl chains of different lengths, using octylamine (OA) and octadecylamine (ODA), and further chemical reduction. Extents of membrane aging were evaluated through changes in gas permeability over time; the separation of gas mixtures comprising carbon dioxide and methane, which are of great interest for industrial applications such as the production of biogas or the purification of natural gas, was carried out. 50:50 vol% CO2/CH4 mixtures were used as feed and separation performance analysed for fresh membranes and at intervals of approximately a month up to 155 days. At the end of this testing period, aged PIM-1 membranes showed a CO2 permeability of (2.0 ± 0.7) × 103 Barrer, which corresponds to a CO2 permeability reduction of 68% from the value obtained right after their fabrication. The addition of alkyl-functionalized GO is shown to be an efficient strategy to retard the physical aging of PIM-1 membranes; filler loadings as low as 0.05 wt% of reduced octyl-functionalized GO showed a CO2 permeability of (3.5 ± 0.6) × 103 Barrer after 5 months, which is almost three quarters higher than that of pure PIM-1 membrane aged for the same time period and represents a reduction of just 39% from its initial value. Moreover, the addition of graphene-like materials to PIM-1 does not affect its mechanical properties.
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•Physical aging of mixed matrix membranes (MMMs) composed of PIM-1 and graphene-like materials was investigated.•A binary CO2/CH4 (50:50 vol%) gas mixtures was used.•Physical aging was reduced by the incorporation of reduced alkyl- functionalized GO nanosheets.•Low filler loadings led to higher reduction in physical aging.
Membrane desalination has become an important solution to global water problems. Graphene-based materials have excellent advantages in the desalination process due to their intriguing features, ...including single atomic layer structure, large specific surface area, hydrophobic property, rich modification approaches, etc. After an introduction of membrane, graphene and graphene oxide (GO), this review systematically summarizes the current progress and gives an insight into the graphene-based separation membranes (GBSMs). The applications of the pressure-driven graphene-based membranes are introduced and their performances are listed and analyzed. By molecular dynamics simulation (MDS), the researchers predict the excellent performances of GBSMs, including high water flux, good salt rejection, etc. which have been verified in subsequent experiments. We believe that the application of graphene-based materials in pressure-driven membrane is worthy of further exploration. Several researchers have prepared electric-driven membranes with graphene-based materials, since their good stabilities and water-retention. However, graphene is not efficient in forward osmosis membrane area for now. In spite of the shortcomings like weak mechanical strength of single layer graphene, difficult to prepare nanopores on graphene film and hard to integrate with polymer, we hold the opinion that graphene-based films still have great research value especially in the membrane separation technology.
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•GBSMs are potentially highly efficient membranes for desalination.•The applications and performances of GBSMs are compared and analyzed.•The defects of GBSMs were briefly mentioned.•GBSMs have promising potential as pressure-driven membrane and electric-driven membrane.
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