Konjac glucomannan/cellulose nanofibers composite aerogel supported HKUST-1 for CO₂ adsorption

Biomass aerogels are attractive in various applications owing to their inherent advantages of renewability, biodegradability and eco-friendly. Herein, a novel composite aerogel of konjac glucomannan (KGM)/TEMPO-oxidized cellulose nanofibers (TOCNF)@HKUST-1 (KTA@HKUST-1) is prepared through a facile vacuum impregnation method combined with the directional freeze-drying process, which using KGM and TOCNF as raw materials. The structural analyses disclose that the KTA@HKUST-1 has a hierarchical porosity, in which HKUST-1 can provide micropores for adsorption, while the meso-/macropores from KTA act as high-speed channels to improve diffusion and mass transfer rate to transport CO₂ components into the micropores of HKUST-1. The experiment results of KTA@HKUST-1-10 (KTA@H10) show that the CO₂ adsorption capacity can reach 3.50 mmol·g^-1 at 1 bar and 298 K, and the adsorption capacity retention rate as high as 91.43% after 7 cycles. In addition, the CO₂/N₂ adsorption selectivity of KTA@H10 can reach 18.42, which has an excellent potential for selective CO₂ adsorption.