Enhanced CO <sub>2</sub> separation properties by incorporating acid-functionalized graphene oxide into polyimide membrane
Weiliang Yuan, Lingzhi Zhu, Chao Luo, Hongguang Liu, Zan Chen, Yanzhen He, Enshan Han
Abstract
Graphene oxide (GO) was modified using isocyanate (MDI) and ethylenediaminetetraacetic acid (EDTA) for the fabrication of flat-sheet GO-MDI-EDTA composite. Subsequently, this composite was incorporated into the Matrimid ® (PI) matrix to fabricate mixed matrix membranes (MMMs) for CO 2 separation. The influence of GO-MDI-EDTA composite on the CO 2 separation properties of PI was evaluated. Scanning electron microscopy showed that GO-MDI-EDTA enhanced the interface compatibility with the polymer matrix. MMMs showed significantly enhanced CO 2 permeability compared with pure Matrimid ® membrane. The improvement of CO 2 separation performance can be attributed to the uniform dispersion of GO-MDI-EDTA sheets in the PI matrix. The carboxylic group contained in GO-MDI-EDTA has a good affinity with CO 2 , and the increased carboxyl sites can effectively transport CO 2 . The GO-MDI-EDTA lamellar structure increased the gas transmission path, which is not conducive to the passage of large dynamic diameter gases (CH 4 , N 2 ), thereby improving the separation performance. The MMMs doped with GO-MDI-EDTA-0.5% showed optimal gas separation performance. The CO 2 permeability is 12.85 Barrer, the CO 2 /N 2 selectivity is 47.59, and the CO 2 /CH 4 selectivity is 53.54.