Covalent organic frameworks for membrane separation

Yuan, Shushan; Li, Xin; Zhu, Junyong; Zhang, Gang; Puyvelde, Peter Van; Bruggen, Bart Van der

doi:10.1039/c8cs00919h

Cited by 792 publications

(446 citation statements)

References 52 publications

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“…Meanwhile, 400 nm–5 μm films were prepared by drop‐casting suspensions of equivalent concentrations (Figure A, Figure S12). Such fine control of film thickness has not been achieved by interfacial polymerization or solvothermal synthetic methods, thus making this approach ideal for fabricating membranes for chemical‐separation applications, where the film thickness and pore size define the performance of the material …”

Section: Resultsmentioning

confidence: 99%

Acid Exfoliation of Imine‐linked Covalent Organic Frameworks Enables Solution Processing into Crystalline Thin Films

et al. 2020

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Covalent organic frameworks (COFs) are highly modular porous crystalline polymers that are of interest for applications such as charge‐storage devices, nanofiltration membranes, and optoelectronic devices. COFs are typically synthesized as microcrystalline powders, which limits their performance in these applications, and their limited solubility precludes large‐scale processing into more useful morphologies and devices. We report a general, scalable method to exfoliate two‐dimensional imine‐linked COF powders by temporarily protonating their linkages. The resulting suspensions were cast into continuous crystalline COF films up to 10 cm in diameter, with thicknesses ranging from 50 nm to 20 μm depending on the suspension composition, concentration, and casting protocol. Furthermore, we demonstrate that the film fabrication process proceeds through a partial depolymerization/repolymerization mechanism, providing mechanically robust films that can be easily separated from their substrates.

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Section: Resultsmentioning

confidence: 99%

Acid Exfoliation of Imine‐linked Covalent Organic Frameworks Enables Solution Processing into Crystalline Thin Films

et al. 2020

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“…On the other hand, integrally skinned asymmetric membranes are known for separating small molecules from the organic feed, with marginal selectivity . Recently, interest in imine based porous organic polymers (POPs), and covalent organic frameworks (COFs), has grown due to their unique porous structures, which could be used for molecular separation with high MWCO . Caro and co‐workers demonstrated the excellent performance of COF‐LZU1 membranes for selective separation of dyes with water permeance of ≈76 L m −2 h −1 bar −1 and favorable rejection (rates exceeding 90%) for water‐soluble dyes larger than 1.2 nm.…”

Section: Water Permeance and Molecular Separation Behavior Of The Polmentioning

confidence: 99%

Large Area Self‐Assembled Ultrathin Polyimine Nanofilms Formed at the Liquid–Liquid Interface Used for Molecular Separation

et al. 2020

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Separation membranes with higher molecular weight cut‐offs are needed to separate ions and small molecules from a mixed feed. The molecular sieving phenomenon can be utilized to separate smaller species with well‐defined dimensions from a mixture. Here, the formation of freestanding polyimine nanofilms with thicknesses down to ≈14 nm synthesized via self‐assembly of pre‐synthesized imine oligomers is reported. Nanofilms are fabricated at the water–xylene interface followed by reversible condensation of polymerization according to the Pieranski theory. Polyimine nanofilm composite membranes are made via transferring the freestanding nanofilm onto ultrafiltration supports. High water permeance of 49.5 L m‐2 h−1 bar−1 is achieved with a complete rejection of brilliant blue‐R (BBR; molecular weight = 825 g mol−1) and no more than 10% rejection of monovalent and divalent salts. However, for a mixed feed of BBR dye and monovalent salt, the salt rejection is increased to ≈18%. Membranes are also capable of separating small dyes (e.g., methyl orange; MO; molecular weight = 327 g mol−1) from a mixed feed of BBR and MO. Considering a thickness of ≈14 nm and its separation efficiency, the present membrane has significance in separation processes.

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“…Among these are the porous organic frameworks (POFs), crystalline covalent organic frameworks (COFs), covalent triazine frameworks (CTFs), polymers of intrinsic microporosity (PIMs), porous aromatic frameworks (PAFs), and amorphous hyper‐crosslinked polymers (AHCPs) . The use of POFs has recently received tremendous attention in the field of molecular sieving membranes . Polycondensation of melamine and aromatic bis ‐aldehydes results in the formation of a microporous polymer network of aminal bonds .…”

Section: Figurementioning

confidence: 99%

Melamine‐Based Microporous Organic Framework Thin Films on an Alumina Membrane for High‐Flux Organic Solvent Nanofiltration

et al. 2019

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Microporous polymer frameworks have attracted considerable attentiont om ake novel separation layers owing to their highly porouss tructure, highp ermeability,a nd excellent molecular separation. Thiss tudy concernst he fabrication and properties of thin melamine-based microporous polymer networks with al ayer thickness of around 400 nm, supported on an a-alumina support and their potentialu se in organic solvent nanofiltration. The modifiedm embranes show excellent solventp urificationp erformances, such as n-heptane permeability as high as 9.2 Lm À2 h À1 bar À1 in combination with avery high rejection of approximately 99 %for organic dyes with molecular weighto f! 457 Da. These values are higher than for the majority of the state-of-the-artm embranes. The membranesf urther exhibit outstanding long-term operation stability.T his work significantly expands the possibilities of using ceramic membranes in organic solventn anofiltration.Supporting Information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.

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Covalent organic frameworks for membrane separation

Abstract: Covalent organic frameworks (COFs), a new class of crystalline porous materials, comprises periodically extended and covalently bound network structures.

Cited by 792 publications

References 52 publications

Acid Exfoliation of Imine‐linked Covalent Organic Frameworks Enables Solution Processing into Crystalline Thin Films

Acid Exfoliation of Imine‐linked Covalent Organic Frameworks Enables Solution Processing into Crystalline Thin Films

Large Area Self‐Assembled Ultrathin Polyimine Nanofilms Formed at the Liquid–Liquid Interface Used for Molecular Separation

Melamine‐Based Microporous Organic Framework Thin Films on an Alumina Membrane for High‐Flux Organic Solvent Nanofiltration

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