Preparation, characterization, and CO2 permeation testing of cellulose acetate and polyimide blend membranes

Abstract

Membrane-based CO2 separation is vital for various applications such as biogas upgradation. Polymer membranes are employed for CO2 separation in the industry. Polymer membranes have a trade-off between selectivity and permeability. Blending polymers is an emerging approach for altering the gas transport in the membranes. This work investigates the fabrication and characterization of blended biodegradable cellulose acetate (CA) with polyimide (PI). Thermal stability was characterized using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and functional groups were analyzed using Fourier transform infrared spectroscopy (FTIR). The morphology of membranes is analyzed using field-emission scanning electron microscope (FESEM). The blend membranes were tested for separation of CO2 from model biogas (CO2/CH4) at room temperature and a low feed pressure (∼1.5 bar). The CA:PI blend membrane composed of 93% CA and 7% PI showed CO2 permeability of 19.71 Barrer, approximately 206% greater than pure CA, and CO2/CH4 selectivity was 9.42. Experimental results are compared with literature on CA-based membranes.