Advanced Membranes最新文献

Osmotic energy is a kind of blue energy that has recently been identified as an additional source of clean energy. Using a membrane-based reverse electrodialysis (RED) process, this blue energy can be obtained from acidic industrial wastewater with different proton concentration gradients. However, this process demands high-performance membrane that can withstand harsh environments, possessing the advantages of wide pH tolerance, high-temperature resistance and chemical stability, developing such membranes remain a challenge. Herein, we report a two-dimensional (2D) lamellar Ti₃C₂T_x MXene membrane-based RED device for osmotic energy capturing from proton gradients. Such a membrane exhibits a typical surface-charge-governed ion transport feature. Moreover, the MXene membrane-based energy harvesting device holds the merits of outstanding pH and temperature resistance. It exhibits an output power density of 6.5 ​W/m² and also demonstrates stability over 200 ​h at pH ​= ​0, which is 30% higher than the commercialization benchmark (5 ​W/m²). The osmotic power density can be further enhanced to 11.1 ​W/m² at 330 ​K, demonstrating excellent thermal and chemical stability. This work can help better understand protons' transport behaviors in MXene membranes and open new avenues for applications in sustainable power conversion and wastewater treatment.

Carbon capture is crucial to reducing anthropogenic carbon emissions and thus mitigating global warming. Owing to the energy-efficient and environmental-benign features, membrane technology holds great potential to achieve highly efficient carbon capture. To realize economically viable membrane technology, developing high-performance membrane materials is of key importance. Recently, organic molecular sieve membranes (OMSMs), not only possessing excellent processability like conventional polymer but also containing high-density, well-defined micropores for molecular differentiation, have attracted increasing research attention. In this review, we discuss recent progress of OMSMs for carbon capture, including the separation of three relevant gas pairs, that is, H₂/CO₂ (pre-combustion capture), O₂/N₂ (oxy-fuel combustion) and CO₂/N₂ (post-combustion capture). Membrane materials including polymers of intrinsic microporosity, thermal-rearranged polymers, covalent organic frameworks, and the emerging hydrogen organic frameworks and porous organic cages, are analyzed. The regulation strategies and stability of micropore structure, and the processability of OMSM materials are summarized. Moreover, we highlight the applications of the OMSMs for the three carbon capture routes. Finally, we conclude with a perspective on the major challenges and the opportunities existing in OMSMs, aiming at identifying the future directions.

Developing novel monomers used for aromatic polyamide membranes is one of the promising modifications to tailor the membranes more efficient. Acyl chloride-based compound as the organic phase reactive monomer is vital to the fabrication of membranes. This study focuses on designing and synthesizing a novel acyl chloride monomer 5-(1-pyrrolidinyl)-1,3-benzenedicarbonyl dichloride (PIPC) based on the purpose of improving membrane permeability and anti-fouling, and preliminarily verify its feasibility for the synthesis of aromatic polyamide membranes. PIPC monomer with a rigid pyrrolidinyl group (–NC₄H₈) was synthesized from three steps of N-alkylation, ester hydrolysis and acylation reaction successively. IR and ¹HNMR spectra were employed to demonstrate the successful synthesis of PIPC. The application of PIPC in the membrane field was also implemented via using PIPC alone as the organic phase reactive monomer, the first/second organic phase reactive monomer, and PIPC and trimesoyl chloride (TMC) together act as the organic phase reactive monomer to react with m-phenylenediamine (MPD) by interfacial polymerization (IP). The MPD-PIPC-TMC membrane prepared by PIPC as the first organic phase reactive monomer exhibited the highest water flux (27.89 ​L ​m⁻² ​h⁻¹), with the increase of 36.8% than the MPD-TMC membrane (20.38 ​L ​m⁻² ​h⁻¹), while maintaining similar salt rejection. The PIPC with a rigid pyrrolidinyl group was demonstrated to be a promising organic phase monomer for further synthesizing high permeability aromatic polyamide membrane, which showed great application prospects in the field of membrane industry.

Biomass-based thin film composites (TFCs) fabricated only from abundant natural resources are emerging as next-generation organic solvent nanofiltration membranes. However, most of the existing membrane fabrication processes still use toxic chemicals, harsh solvents, and fossil-based supports. We report a plant-based, green TFC membrane based solely on sustainable resources. It is the thinnest defect-free nanofilm (only 12-nm-thick) fabricated only from natural resources. Dialdehyde starch was crosslinked with priamine at the interface of a water–eucalyptol solvent system. Interfacial polymerization occurred on a biodegradable cellulose acetate support obtained using phase inversion. The membrane has an ultrathin (12-nm-thick) selective layer, and the molecular weight cut-off and permeance were fine-tuned between 366 and 624 ​g ​mol⁻¹ and 7 and 23 ​L ​m⁻² ​h⁻¹ ​bar⁻¹, respectively. Stable nanofiltration performance under continuous crossflow filtration was achieved for seven days. The sustainability of the membrane fabrication platform was compared with those of other platforms. Our TFC membrane fabrication platform enables the conversion of biomass-based building blocks into high-value-added products.

Membrane separation has provided efficient solutions for addressing energy and environmental challenges over the past few decades due to its low energy consumption, convenient operation, and reduced secondary pollution. An energy-efficient membrane separation process usually requires high-performance membranes with outstanding chemical, mechanical properties, special nanostructures, and superior separation characteristics. Hence, considerable effort has been devoted to finding and designing new membrane materials with optimized membrane structures. In recent years, researchers have gained deep knowledge of learning biomimetic concepts or strategies from nature for designing energy-efficient separation membranes with favorable structures. This is because, after 4.5 billion years of evolution, the world of nature has become a natural school for scientists and engineers, which has offered astonishing solutions/inspirations for designing more sustainable separation materials. In this review, particular attention is paid to knowledge from nature for the design of separation membranes and recent advancements in their design strategies. Additionally, natural functional materials that have been utilized in the replacement of conventional fossil-based materials for membrane production are reviewed. Present challenges and directions for the development of next-generation membranes are also discussed.

Graphene oxide (GO) films are highlighted to have great potential in water purification. The highly chemical and thermally stable polyacrylonitrile (PAN) competently constructs a superior substrate supporting the ultrathin GO laminates under various aqueous environments. However, the lack of available functional groups of PAN substrate, which inevitably leads to an undesirable water-induced peeling of the stacked GO laminates, greatly limits its practical application in constructing a stable GO composite membrane. A hydrolysis-condensation-induced bridge strategy is reported in which a bio-inspired molecular bridge generates a strong adhesion of PAN substrate to GO laminate, meanwhile interlaminar molecular bridges also form to generate a robust GO laminate with excellent resistance to swelling. Such GO composite membranes exhibit structural durability in the treatment of dye-containing wastewater for several days or even longer. The interfacial molecular bridge has little effect on the size-sieving and unique transport capability of the GO laminates. Comparable water permeability with the pristine GO laminates and nearly complete rejection to dyes (i.e. Congo red, methylene blue, and methyl orange) were obtained. The combination of easy fabrication, robust stability, and high performance make the PAN-supported GO membranes advantageous for practical application in textile wastewater purification.

Membrane materials with excellent selectivity and high permeability are the key for high-efficiency membrane separation. New-type porous materials have developed as ideal building blocks for molecular sieving membranes due to their inherent properties, such as permanent porosity, high surface area, structural diversity and low mass transfer barriers. In actual industrial promotion and separation applications, porous materials need to be combined with substrates to prepare porous composite membranes. In order to reduce costs and increase processing flexibility, the combination of organic polymer substrates and porous materials has received more attentions. The multifunctional design strategy of the membrane material and membrane structure of porous composite membranes based on the organic subatrates is the key to realize the further improvement of mass transfer. In this review, we focus on the organic matrix porous composite membrane based on the participation of inorganic-organic hybrid materials and organic-organic composite materials, and conduct an in-depth discussion on the transport mechanism of porous composite membranes, and highlight diverse structural control strategies from the perspectives of macrostructural design and microstructural regulation of membrane structures. Finally, the applications of porous composite membrane based on organic substrate in precise molecular sieving are summarized, and the future opportunities and challenges in this field are discussed briefly.

Gas separation (GS) and pervaporation (PV) mainly based on solution-diffusion mechanism, are two important processes for the challenging transport and separation of gaseous and vapor molecules. Various types of contemporary nanomaterials such as covalent organic frameworks (COFs) and metal organic frameworks (MOFs) have demonstrated unique channels with tuneable surface that govern transport and separation of targeted molecules. New opportunities have been revealed through incorporation of emerging nanomaterials into the structure of conventional polymeric membranes and resulted in several advantages notably improved performance and reduced energy consumptions. Due to the broad applications of GS and PV processes in the chemical industry and energy sector, the present manuscript aims to review the principle for gas separation and pervaporation in membrane molecular separation process in terms of solution-diffusion theory. In addition, the current status of membranes containing emerging nanomaterials for GS and PV are discussed comprehensively from different aspects. Furthermore, the current applications of nanomaterials incorporated mixed matrix membranes (MMMs) are described. Finally, the perspectives and future directions of remarkable performance membranes incorporated with diverse emerging nanomaterials are explained so as to facilitate the rapid advancement of energetic-efficient membranes toward practically industrial applications.

Alkaline zinc-iron flow battery (AZIFB) is promising for stationary energy storage to achieve the extensive application of renewable energies due to its features of high safety, high power density and low cost. However, the major bottlenecks such as the occurrence of short circuit, water migration and low efficiency have limited its further applications, of which an ion-conducting membrane acts as a pivotal role in addressing these issues. The benchmark Nafion series membranes or anion-exchange membranes are confronted with their low ionic conductivity or poor stability in alkaline media. Therefore, a membrane is required to possess (1) excellent stability to avert the occurrence of short circuit resulted from the destruction of zinc dendrite and degradation of membrane caused by alkaline media, (2) low area resistance and high selectivity to achieve a high efficiency in time of the charge-discharge procedure of AZIFB. In this review, we will start from a brief introduction of AZIFB and cover the categories of membranes applied in AZIFB. And then the fundamental aspects of the membrane, including ion transport mechanism, fabrication & structure design and performance optimization will be highlighted. Finally, the challenges and prospects of the membranes for AZIFB applications will be briefly proposed and discussed.