Porous polymers have received an increased interest as CO2 sorbents due to combining the properties of both porous structure and polymers. High internal phase emulsion (HIPE) as a template by Oil-in-Water (O/W) system and photopolymerization technique was used to prepare crosslinked Acrylamide-co-Acrylic acid (AAM-co-AAC) hydrogel monolith. Also, photopolymerization followed by freeze granulation was utilized for the fabrication of the AAM-co-AAC hydrogel granules. The structural analysis of synthesized scaffolds confirmed crosslinked copolymer. The scanning electron microscopy (SEM) micrographs presented porous structure for monolith consists of a “skeleton copy” of the O/W HIPE where granules revealed many severe wrinkles on the surface. Monoliths and granules exhibited BET surface areas around 24 m2/g and 28 m2/g respectively. The CO2 uptake ability of synthesized scaffolds for dry scrubbing as well in aqueous media (wet scrubbing) was investigated. The CO2 adsorption capacity of monoliths and granules reached to saturation at 25 kPa to 0.5 and 0.8 mmol/g, respectively which were higher than adsorption values reported for amide-based porous polymers [1,2]. The electron-rich groups like NH2, C=O, and R-O-R in the structure of block copolymer can interact with CO2 molecules and give rise to the higher adsorption capacity. The CO2 and N2 adsorption isotherms for granules and monoliths indicated the selectivity of AAM-co-AAC copolymer for CO2 gas. Furthermore, the granules were able of capturing CO2 in aqueous media where the absorption of CO2 on water-swollen granules increased with increasing the amount of water. The CO2 capture capacity reached to 1.8 mmol/g in completely swollen granules. The uptake of CO2 in aqueous solution contributes from the physical dissolution of CO2 in water along with interactions between the functional groups of the hydrogels and gas molecules. The results revealed the CO2 dry and wet scrubbing ability of the synthesized hydrogel copolymers .
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2. F. U. Shah, et al., Magn. Reson. Chem. 54 (2016) 734-739.
3. D. Nikjoo, et al., J. CO2 Utilization 21 (2017) 473–479.