Water-swollen carboxymethyl chitosan (CMC) /polyamide (PA) membranes with octopus-branched nanostructures for CO2 capture

Developing efficient membrane technology for CO2 capture has aroused wide interest for environment conservation and emission reduction. Developing facilitated transport membranes is a potential strategy for improving CO2 permeance and CO2/N2 selectivity synchronously, based on the reversible reactions among carriers and CO2 molecules. The reaction activity can be optimized by tuning the carrier mobility due to the enhanced water-swelling capacity. Here, thin-film composite (TFC) membranes containing water-swelling carboxymethyl chitosan (CMC) chains were prepared via interfacial polymerization process, aiming to improve CO2 separation performance. As-prepared TFC membranes with different CMC loading have exhibited different Turing nanostructures, such as corrugated structures, octopus-branched structures and nodular structures. Water can enhance the activity of carriers in reversible reaction for facilitated transport membranes. TFC membranes with CMC have exhibited the enhanced water-swelling capacity, showing high CO2 permeance of 1278 GPU together with CO2/N2 selectivity of 89. This work put forward a simple and effective method to tune the membrane structure and enhance the facilitated transport.