Search

Membranes are important in the pharmaceutical industry for the separation of antibiotics and salts. However, its widespread adoption has been hindered by limited control of the membrane microstructure (pore architecture and free‐volume elements), separation threshold, scalability, and operational stability. In this study, 4,4′,4′′,4′′′‐methanetetrayltetrakis(benzene‐1,2‐diamine) (MTLB) as prepared as a molecular building block for fabricating thin‐film composite membranes (TFCMs) via interfacial polymerization. The relatively large molecular size and rigid molecular structure of MTLB, along with its non‐coplanar and distorted conformation, produced thin and defect‐free selective layers (~27 nm) with ideal microporosities for antibiotic desalination. These structural advantages yielded an unprecedented high performance with a water permeance of 45.2 L m−2 h−1 bar−1 and efficient antibiotic desalination (NaCl/adriamycin selectivity of 422). We demonstrated the feasibility of the industrial scaling of the membrane into a spiral‐wound module (with an effective area of 2.0 m2). This module exhibited long‐term stability and performance that surpassed those of state‐of‐the‐art membranes used for antibiotic desalination. This study provides a scientific reference for the development of high‐performance TFCMs for water purification and desalination in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

Crystalline porous materials (CPMs), including covalent organic frameworks (COFs) and metal–organic frameworks (MOFs), are promising materials for advanced separation technologies. However, the challenge of transforming nanoscale CPMs into large‐area functional membranes hinders their application in the membrane separation process. Herein, a self‐standing pure COF (TpPa‐1) nanofiber membrane with high crystallinity, good flexibility, excellent mechanical properties, and scalability is prepared using an electrospinning process and polymer sacrificial template strategy. Subsequently, the COF nanofiber membrane is innovatively used to replace traditional inorganic discs, metal meshes, and polymer membranes as porous supports, and the COF–MOF composite CPM membrane is prepared through the tailorable and confined growth of zeolite imidazolium salt frame‐8 (ZIF‐8) on the surface of the COF membrane and in the gaps of the COF nanofibers. The COF–MOF composite membrane exhibits excellent permeability and significantly enhances separation selectivity for organic dyes. Moreover, MOF and COF form an interpenetrating network structure, and their similar chemical properties improve the interfacial stability between the two phases, giving the COF–MOF composite membrane good long‐term separation performance. This is the first self‐standing composite CPM membrane with excellent molecular sieving performance, which provides new insights into the design of high‐performance and robust composite membranes. [ABSTRACT FROM AUTHOR]

The development of carbon dioxide (CO2) separation technology is crucial for mitigating global climate change and promoting sustainable development. In this study, we successfully synthesized an array of cross‐linked poly(vinyl alcohol) (PVA) membranes, xALD‐PEG‐ALD‐c‐PVA, with enhanced CO2/N2 separation performance by employing dialdehyde polyethylene glycol (ALD‐PEG‐ALD) as a cross‐linker. The formation of the cross‐linked network structure not only inhibits the crystallization of PVA but also disrupts hydrogen bonding and thus increases fractional free volume of PVA chains. Under the synergistic effect of these multiple factors, the cross‐linked PVA membranes exhibit a significantly improved CO2 permeability. Moreover, they maintain high CO2/N2 selectivity, attributing to the CO2‐philic characteristic of ethylene oxide groups in the cross‐linked structure. At the ALD‐PEG‐ALD content of 1.6 mmol g−1, the xALD‐PEG‐ALD‐c‐PVA membrane demonstrates a CO2 permeability of 41.4 barrer and a CO2/N2 selectivity of 57.4 at 2 bar and 25°C. Furthermore, compared with the pristine PVA membrane, xALD‐PEG‐ALD‐c‐PVA membranes manifest superior mechanical properties and outstanding separation performance for a CO2/N2 (15/85, vol%) gas mixture. The excellent combination of permeability and selectivity makes xALD‐PEG‐ALD‐c‐PVA membranes highly promising for various CO2 separation applications. [ABSTRACT FROM AUTHOR]

Covalent organic framework (COF) membranes featuring uniform topological structures and devisable functions, show huge potential in water purification and molecular separation. Nevertheless, the inability of uniform COF membranes to be produced on an industrial scale and their nonenvironmentally friendly fabrication method are the bottleneck preventing their industrial applications. Herein, we report a new green and industrially adaptable scraping‐assisted interfacial polymerization (SAIP) technique to fabricate scalable and uniform TpPa COF membranes. The process used non‐toxic and low‐volatility ionic liquids (ILs) as organic phase instead of conventional organic solvents for interfacial synthesis of TpPa COF layer on a support membrane, which can simultaneously achieve the purposes of (i) improving the greenness of membrane‐forming process and (ii) fabricating a robust membrane that can function beyond the conventional membranes. This approach yields a large‐area, continuous COF membrane (19×25 cm2) with a thickness of 78 nm within a brief period of 2 minutes. The resulting membrane exhibited an unprecedented combination of high permeance (48.09 L m−2 h−1 bar−1) and antibiotic desalination efficiency (e.g., NaCl/adriamycin separation factor of 41.8), which is superior to the commercial benchmarking membranes. [ABSTRACT FROM AUTHOR]

Urgent needs for the removal of volatile organic compounds (VOCs) from gas streams has stimulated a vigorous research for high‐performance separation membranes. Herein, porous iron‐organic molecular cage (Fe‐cage) embedded polydimethylsiloxane (PDMS) mixed miatrix membranes (MMMs) were fabricated through emulsion casting method for efficient VOCs removal. The membrane separation performance was systematically investigated by separating VOC/N2 gas mixtures under various operating conditions (e.g., feed concentration, operating temperature) using n‐hexane, n‐heptane, and cyclohexane as model organic vapors. It was found that the resultant membranes demonstrated homogeneous Fe‐cage dispersion and intimate interfacial adhesion. With the increase of the Fe‐cage loading, the MMMs demonstrated obviously improved permselectivity for the separation of n‐hexane/N2 and n‐heptane/N2. The MMM containing 4 wt% Fe‐cage showed a n‐heptane permeability of 1657 × 10−8 mol μm m−2 s−1 Pa−1 and a n‐heptane/N2 selectivity of 145 at 25°C when the feed concentration is 4.3 mol%. These values were 231% and 158% of those for the pristine PDMS membrane, respectively. Furthermore, the VOC permeability and VOC/N2 selectivity of the membranes increased with decreasing operating temperature or increasing feed concentration. Because of its excellent mixed‐gas VOC/N2 permselectivity, the Fe‐cage embedded PDMS membrane could find use in petrochemical applications such as gasoline vapor recovery. [ABSTRACT FROM AUTHOR]

Polydopamine (PDA) can greatly affect polymer's properties, due to the chemical and physical interactions between the polymers and PDA. In this study, PDA was demonstrated to adjust the pore structures and increase the mechanical properties of alginate hydrogel‐based cartilage tissue scaffolds. Dopamine modified alginate (Alg‐DA) was firstly synthesized by modification of Alg with DA. Alg‐DA interacted with preprepared PDA nanoparticles and further crosslinked with calcium ions (Ca2+) to form the hydrogel scaffold (Alg‐DA/PDA). The Alg‐DA/PDA scaffold combined multiple advantageous features, including continuous pore structure, high level of porosity, well mechanical properties, good biocompatibility and appropriate cycle life of degradation. Moreover, it could provide an optimized forming environment for hydroxyapatite (HAp) by mineralization process, thus accelerating cartilage repair. The improved performances were mainly ascribed to physical enhancement of the PDA nanoparticles and crosslinking points among the polymers and catechol groups in DA. These findings might offer a guideline for fabricating robust biocompatible cartilage tissue scaffold. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3255–3266, 2018. [ABSTRACT FROM AUTHOR]