Abstract
Realization of suitable membrane-based technology for efficient CO2 capture to mitigate climate change relies on the development of thin-film composite (TFC) membranes with superior separation performance. Graphene oxide (GO), due to its 2D morphology, intrinsic strength and chemical compatibility, was used as a nanofiller to enhance CO2 separation performance and stability of a facilitated transport membrane. SHPAA (sterically hindered polyallylamine)-based blend matrix was selected as the polymeric matrix material in this work. The high aspect ratio of GO-based fillers, when coupled with optimized coating protocol, resulted in TFC membranes of ultrathin (200 nm) selective layers with the in-plane orientation of nanoplatelets, leading to enhanced separation properties that can be retained for long term. Porous graphene oxide (pGO) was also incorporated as nanofillers, resulting in significantly improved gas permeation at a very low filler loading of 0.2 wt%; A CO2 permeance of up to 607 GPU with a CO2/N2 separation factor of 36 in flat-sheet configuration was documented. Chemical modification of GO with PEG groups was found to further increase the selectivity of the membranes but reduces the CO2 permeance, showing a CO2/N2 separation factor of 90 with a CO2 permeance of 205 GPU. The effect of various 2D nanoplatelets on CO2 transport properties in the membranes of hydrophilic PVA (polyvinyl alcohol) matrix and facilitated transport SHPAA/PVA matrix was elucidated with respect to the nanofiller property and loading.
Highlights
The global climate crisis is believed to be primarily due to industri alisation
The incorporation of 2 dimensional (2D) nanoplatelets in facilitated transport membranes has rarely been reported in the form of ultrathin selective layers less than 500 nm suitable for application in CO2 separation
Both Graphene oxide (GO) and physically modified Porous graphene oxide (pGO) are characterized by significant peaks that originate from C–C at ~285 eV and from C–O at ~287 eV
Summary
The global climate crisis is believed to be primarily due to industri alisation. Of all the causes, the tremendous increase in greenhouse gas emissions, most importantly, the emission of CO2, over the past few decades, could be directly coupled to the current global warming sce nario. Facilitated transport membrane is considered one of the successful approaches to overcome the trade-off and thereby improve separation performance, which uses CO2-reactive carriers to enhance CO2 transport. Another approach is to make hybrid membranes to combine the advantages of inorganic materials, including the use of nano-sized fillers to make nanocomposite membranes, which syn ergistically exploit properties arising at the nanoscale [9,10,11,12]. Limited studies have reported the combination of these two approaches to increase water uptake of facilitated transport membranes by taking advantages of the hydrophilicity of the added filler phase and to enhance the mechanical stability of the fully swollen membrane matrix except for a few reports [13,14,15]. The fabrication of the TFC membrane with such ultrathin selective layers comprising of 2D nano platelets in facilitated transport membranes using a scalable fabrication procedure seems challenging
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