Fabrication of Cellulose Acetate-Based Membrane Doped with Plasticizer for High-Efficiency Separation of CO₂

It is essential to develop a practical technology for the separation and capture of carbon dioxide (CO₂) due to the gradually increased concentration of CO₂ in the atmosphere, which has driven the rise in global temperature. Membrane separation is regarded as a promising technology for the capture of CO₂. However, most membranes employ non-biodegradable petroleum-based polymers. In this study, biodegradable and renewable membranes of cellulose acetate (CA) doped with polyethylene glycol (PEG) and polyethylene glycol diacrylate (PEGDA) were fabricated by solution casting and used for the separation of CO₂/O₂. The results indicated that the membrane doped with PEGDA exhibited higher permeability of CO₂ and selectivity of CO₂/O₂ compared to those doped with PEG, while improving the tensile strain and structural uniformity of membranes. The membrane with a thickness of 25 μm at a PEGDA dosage of 10 wt% achieved optimal gas permeability, selectivity, and mechanical toughness, showing CO₂ permeability of 4.59 Barrer and CO₂/O₂ selectivity of 5.68. The structure of the interpenetrating polymer network was responsible for the excellent properties of the membrane doped with PEGDA due to the formation of more mid- and micro-sized pores that increase the diffusion pathways of CO₂.