scholarly journals Reducing the Pore Size of Covalent Organic Frameworks in Thin-Film Composite Membranes Enhances Solute Rejection

2019 ◽  
Author(s):  
Amanda Corcos ◽  
Gabrielle Levato ◽  
Zhiwei Jiang ◽  
Austin Evans ◽  
Andrew Livingston ◽  
...  
Keyword(s):  
Thin Film ◽  
Pore Size ◽  
Organic Pollutant ◽  
Composite Membranes ◽  
Systematic Difference ◽  
Film Composite ◽  
Thin Film Composite ◽  
Active Layers ◽  
Rhodamine Wt ◽  
Effective Pore Size

Three imine-linked covalent organic framework (COF) films are incorporated as active layers into separate thin-film composite (TFC) membranes and tested for their ability to reject an organic pollutant surrogate and salt from water. The synthesized membranes consist of a polyacrylonitrile (PAN) membrane supporting a <b>TAPB-PDA-H</b>, <b>TAPB-PDA-Me</b>, or <b>TAPB-PDA-Et</b> COF thin film. The latter two COFs direct six methyl and ethyl substituents per tiled hexagon into the pores, respectively, while maintaining the same topology across the series. These substituents decrease the effective pore size of the COF compared to the parent <b>TAPB-PDA-H</b> COF. The <b>TAPB-PDA-Me</b> membrane rejects Rhodamine-WT (R-WT) dye and NaCl better than the <b>TAPB-PDA-H</b> membrane, and the <b>TAPB-PDA-Et</b> membrane exhibits the best rejection overall. The solution-diffusion model used to analyze this permeation behavior indicates that there is a systematic difference in rejection as subsequent pendant groups are added to the interior of the COF pore. These findings demonstrate the concept of tuning the selectivity of COF membranes by systematically reducing the effective pore size within a given topology.<br>

scholarly journals Reducing the Pore Size of Covalent Organic Frameworks in Thin-Film Composite Membranes Enhances Solute Rejection

2019 ◽  
Author(s):  
Amanda Corcos ◽  
Gabrielle Levato ◽  
Zhiwei Jiang ◽  
Austin Evans ◽  
Andrew Livingston ◽  
...  
Keyword(s):  
Thin Film ◽  
Pore Size ◽  
Organic Pollutant ◽  
Composite Membranes ◽  
Systematic Difference ◽  
Film Composite ◽  
Thin Film Composite ◽  
Active Layers ◽  
Rhodamine Wt ◽  
Effective Pore Size

Three imine-linked covalent organic framework (COF) films are incorporated as active layers into separate thin-film composite (TFC) membranes and tested for their ability to reject an organic pollutant surrogate and salt from water. The synthesized membranes consist of a polyacrylonitrile (PAN) membrane supporting a <b>TAPB-PDA-H</b>, <b>TAPB-PDA-Me</b>, or <b>TAPB-PDA-Et</b> COF thin film. The latter two COFs direct six methyl and ethyl substituents per tiled hexagon into the pores, respectively, while maintaining the same topology across the series. These substituents decrease the effective pore size of the COF compared to the parent <b>TAPB-PDA-H</b> COF. The <b>TAPB-PDA-Me</b> membrane rejects Rhodamine-WT (R-WT) dye and NaCl better than the <b>TAPB-PDA-H</b> membrane, and the <b>TAPB-PDA-Et</b> membrane exhibits the best rejection overall. The solution-diffusion model used to analyze this permeation behavior indicates that there is a systematic difference in rejection as subsequent pendant groups are added to the interior of the COF pore. These findings demonstrate the concept of tuning the selectivity of COF membranes by systematically reducing the effective pore size within a given topology.<br>

scholarly journals Towards a High-Flux Separation Layer from Hexagonal Lyotropic Liquid Crystals for Thin-Film Composite Membranes

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 842
Author(s):  
Senlin Gu ◽  
Bao Yuan ◽  
Bo Bai ◽  
Xin Tong ◽  
Luke A. O’Dell ◽  
...  
Keyword(s):  
Thin Film ◽  
Liquid Crystals ◽  
Pore Size ◽  
Water Flux ◽  
Composite Membranes ◽  
Lyotropic Liquid Crystals ◽  
Hydrophobic Substrate ◽  
Film Composite ◽  
Thin Film Composite ◽  
Significant Difference

Hexagonal lyotropic liquid crystals (HLLC) with uniform pore size in the range of 1~5 nm are highly sought after as promising active separation layers of thin-film composite (TFC) membranes, which have been confirmed to be efficient for water purification. The potential interaction between an amphiphile-based HLLC layer and the substrate surface, however, has not been fully explored. In this research, hydrophilic and hydrophobic microporous polyvinylidene fluoride (PVDF) substrates were chosen, respectively, to prepare TFC membranes with the active layers templated from HLLC, consisting of dodecyl trimethylammonium bromide, water, and a mixture of poly (ethylene glycol) diacrylate and 2-hydroxyethyl methacrylate. The pore size of the active layer was found to decrease by about 1.6 Å compared to that of the free-standing HLLC after polymerization, but no significant difference was observable by using either hydrophilic or hydrophobic substrates (26.9 Å vs 27.1 Å). The water flux of the TFC membrane with the hydrophobic substrate, however, was higher than that with the hydrophilic one. A further investigation confirmed that the increase in water flux originated from a much higher porosity was due to the synergistic effect of the hydrophilic HLLC nanoporous material and the hydrophobic substrate.

Interfacially polymerized thin-film composite membranes: Impact of support layer pore size on active layer polymerization and seawater desalination performance

2019 ◽  
Vol 212 ◽  
pp. 438-448 ◽  
Author(s):  
Jalal-Al-Din Sharabati ◽  
Serkan Guclu ◽  
Selda Erkoc-Ilter ◽  
Derya Y. Koseoglu-Imer ◽  
Serkan Unal ◽  
...  
Keyword(s):  
Thin Film ◽  
Pore Size ◽  
Active Layer ◽  
Composite Membranes ◽  
Seawater Desalination ◽  
Film Composite ◽  
Thin Film Composite
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