Dual-Modulated Polyamide Membranes Based on Vapor–Liquid Interfacial Polymerization for CO₂ Separation

Polyamide (PA) membranes show great application potential in the CO 2 separation study. However, the PA membranes prepared by the traditional interfacial polymerization (IP) have a dense microstructure and a singularity of functional groups, making it difficult to exhibit both high CO 2 permeance and selectivity. Herein, we report a new dual-modulation strategy by preparation method optimization and filler modification to improve the CO 2 separation performance of the PA membranes. The PA membranes prepared by vapor–liquid IP have a loose microstructure, which greatly improves the gas permeance. The introduction of mono-(6-ethanediamine-6-deoxy)-beta-cyclodextrin (CD) can better loosen the PA microstructure, and the CO 2 -philic groups in the CD boost the CO 2 selectivity by the facilitated transport effect. Ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate is further sealed into PA membranes to remedy the possible microvoids or defects and CD cavities of the membrane microstructure. The prepared membranes display excellent CO 2 separation performance with CO 2 /H 2, CO 2 /CH 4, and CO 2 /N 2 selectivity of 8.2, 45.5, and 116.9, as well as a CO 2 permeance of about 320 GPU. The proposed strategy provides a facile and effective route to dual-modulated PA membranes for the study of CO 2 separation and can be expanded to other macrocyclic molecules and ionic liquid systems.