Asymmetric oxygen‐functionalized carbon nanotubes dispersed in polysulfone for CO₂ separation

Abstract Carbon dioxide separation from flue gases is an important challenge to be faced. Membrane processes are a promising alternative to increase technical and economical constraints once the development of materials with superior characteristics are attained. Integrally asymmetric mixed matrix membranes (MMMs) were prepared by dry/wet phase inversion process of polysulfone (PSF) containing oxygen‐functionalized multiwalled carbon nanotubes (MWNT‐O). Fourier transform infrared (FTIR) spectroscopy confirmed the presence of MWNT‐O in MMMs. Thermal gravimetric analysis (TGA) showed that MMMs are stable up to 150°C. Photomicrographs from scanning electron microscopy (SEM) revealed that MMMs consist of an asymmetric structure with a skin layer supported on a sponge‐like substructure. The pore size of the support of MMMs increased with MWNT‐O content from 0.4 to 0.8 wt.% and the thickness of the dense layer decreased. However, when the content of MWNT‐O increased to 1 wt.%, the pore size decreased, and the dense layer increased. Therefore, MMMs changed CO 2 separation performance. For 1 wt.% MWNT‐O loading compared to the neat polymer, CO 2 permeance and CO 2 /N 2 selectivity was increased from 1.5 to 2.7 GPU, and from 9.5 to 14.3, respectively.