Blend Cellulose Acetate Butyrate Membrane with Molecular Weight 12,000, 30,000 and 65,000 for CO2/N2 Separation

Abstract

The demand for energy has been increasing gradually due to the rapid growth of the global economy. The emission of greenhouses gases (GHGs) especially, carbon dioxide (CO2), which is a major greenhouse gas, has contributed to the global warming issue. Therefore, to reduce emissions and eliminate the serious consequences, membrane separation technology was introduced as an alternative option that has high CO2 separation efficiency. It requires lower energy consumption, lower capital costs and it is commercial and environmentally friendly. Most importantly, it is easy to operate. In this study, the blend cellulose acetate butyrate (CAB) membrane was synthesised from the CAB polymers using the wet-phase inversion method with molecular weights of 12,000:30,000:65,000 in the ratio of 1:2:2, respectively. The blend CAB membrane casted at 250 μm (M2) was the best performing membrane among all the membranes due to its relatively high CO2 gas permeance and the highest CO2/N2 selectivity, which were 7,560.80 ± 20 GPU and 1.5319 ± 0.05, respectively. The fabricated CAB membrane was then characterised by using the Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR) and surface contact angle. It showed strong stretching bands around 1,044.07 cm−1, 1,226.25 cm−1 and 1,744.04 cm−1, which indicated a single bond C-O and carboxyl group (C=O). The higher the hydrophobicity of the membrane, the stronger the affinity for CO2 molecules. In this case, the contact angle of the membrane casted at 150 μm (M1) was 120.460, which was the highest. This newly synthesised CAB membrane is expected to benefit major industries by its cost effective and high energy saving properties. Most importantly, the gas separation efficiencies are better than the current technologies.