Graphene oxide (GO) nanosheets stacked in parallel with subnanometer channels can exhibit an excellent size‐sieving ability for membrane‐based gas separation. However, gas molecules have to diffuse through the tortuous nanochannels, leading to low permeability. Herein we demonstrate two versatile approaches to modify the GO (before membrane fabrication by vacuum‐filtration) to collectively increase gas permeability, etching using hydrogen peroxide to generate in‐plane nanopores and acidifying using hydrochloric acid. For example, a membrane prepared at a pH of 5.0 using the 4‐h‐etched GO (HGO‐4h) shows He permeability of 5.3 Barrer and He/CH4selectivity of 800, which are 5 times and 1.5 times those of the GO membranes, respectively. Decreasing the pH from 5.0 to 2.0 for HGO‐4h enhances He permeability to 57 Barrer and He/CH4selectivity to 1,800. The HGO‐4h prepared at the pH of 2.0 exhibits separation properties of H2/CO2, H2/N2, He/N2, and He/CH4surpassing their corresponding upper bounds.
Polymeric membrane‐based gas separation technology has significant advantages compared with traditional amine‐based CO2separation method. In this work, SEBS block copolymer is used as a polymer matrix to incorporate triethylene oxide (TEO) functionality. The short ethylene oxide segment is chosen to avoid crystallization, which is confirmed by differential scanning calorimetry and wide‐angle X‐ray scattering characterizations. The gas permeability results reveal that CO2/N2selectivity increased with increasing content of TEO functional group. The highest CO2permeability (281 Barrer) and CO2/N2selectivity (31) were obtained for the membrane with the highest TEO incorporation (57 mol%). Increasing the TEO content in these copolymers results in an increase in CO2solubility and a decrease in C2H6solubility. For example, as the grafted TEO content increased from 0 to 57 mol%, the CO2solubility and CO2/C2H6solubility selectivity increased from 0.72 to 1.3 cm3(STP)/cm3atm and 0.47 to 1.3 at 35°C, respectively. The polar ether linkage in TEO‐grafted SEBS copolymers exhibits favorable interaction with CO2and unfavorable interaction with nonpolar C2H6, thus enhancing CO2/C2H6solubility selectivity.
more » « less- NSF-PAR ID:
- 10453143
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Polymer Science
- Volume:
- 58
- Issue:
- 18
- ISSN:
- 2642-4150
- Page Range / eLocation ID:
- p. 2654-2663
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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