Enhanced dual-gas adsorption of ammonia and acetaldehyde via Cu-BTC/ZIF-8 MOF-on-MOF structures grown on cellulose acetate nanofibers

The simultaneous removal of ammonia (NH₃) and acetaldehyde (C₂H₄O), two hazardous volatile organic compounds, is essential for air quality improvement. In this study, cellulose acetate (CA) nanofibers were functionalized with the MOF-on-MOF type of Cu₃(1,3,5-benzentricarboxylate)₂ and zeolite imidazolate framework (ZIF)-8 metal–organic frameworks (MOFs) to enhance their dual-gas adsorption performance. Under single-gas conditions, the porous CA-based MOF-on-MOF type of Cu-BTC/ZIF-8 nanofibers (CACu/ZIF) achieved adsorption capacities of 77.4 × 10⁻² mmol/g for NH₃ and 3.25 × 10⁻² mmol/g for C₂H₄O. Remarkably, under mixed-gas conditions, the adsorption capacities increased to 82.8 × 10⁻² mmol/g for NH₃ and 7.83 × 10⁻² mmol/g for C₂H₄O, demonstrating a significant enhancement in acetaldehyde adsorption. This improvement was attributed to the synergistic interactions between NH₃ and C₂H₄O, with NH₃ facilitating the formation of C–N bonds with acetaldehyde, thereby promoting additional adsorption. The hierarchical porous structure of CACu/ZIF provided abundant active sites for maximizing adsorption efficiency. These results indicate that MOF-functionalized nanofibers can effectively capture multiple pollutants, making them promising candidates for advanced air purification applications. This study highlights the importance of mixed-gas interactions in adsorption processes and provides valuable insights into the optimization of nanofibers for air purification.