Biomimetic hydroxypropyl-β-cyclodextrin (Hβ-CD) / polyamide (PA) membranes for CO2 separation

Abstract

Carbonic anhydrase (CA)-inspired membranes for CO2 separation were constructed by introducing hydroxypropyl-β-cyclodextrins (Hβ-CDs) into the polyamide networks, which were formed via interfacial polymerization reactions between trimesoyl chloride and tertiary amino-containing monomers. Hydrophobic inner cavities of Hβ-CDs with the hydrophilic exterior can be used to simulate the hydrophobic pockets of CA enzymes. Hydrophilic and hydrophobic regions were constructed via introducing Hβ-CDs into membranes, while the transport of nonpolar CO2 molecules and polar components (H2O and HCO3−) in CO2 hydration reactions could be enhanced. Meanwhile, tertiary amino groups in biomimetic membranes can act as the base catalysts for CO2 hydration reactions, which were deemed as carriers for facilitated transport membranes. Biomimetic membranes containing Hβ-CDs and tertiary amino groups exhibited outstanding CO2 permeance of 2792 GPU and CO2/N2 selectivity of 171 at 0.15 MPa, showing the potentials for low-pressure CO2 capture. Particularly, CO2 transport mechanisms were also analyzed for biomimetic facilitated-transport membranes, which can supply new visions for developing novel membrane materials for CO2 separation.