Amide Link Scission in the Polyamide Active Layers of Thin-Film Composite Membranes upon Exposure to Free Chlorine: Kinetics and Mechanisms

2015 ◽  
Vol 49 (20) ◽  
pp. 12136-12144 ◽  
Author(s):  
Joshua Powell ◽  
Jeanne Luh ◽  
Orlando Coronell
Keyword(s):  
Thin Film ◽  
Composite Membranes ◽  
Free Chlorine ◽  
Film Composite ◽  
Thin Film Composite ◽  
Active Layers

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>

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