An investigation on the effects of both amine grafting and blending with biodegradable chitosan membrane for CO2 capture from CO2/N2 gas mixtures

The fusion of amine carriers into rubbery or glassy polymeric membranes is always preferred over neat polymeric membranes due to their enhanced CO2/light gas separation performances. However, few studies compare the effects of two approaches: amine blending and grafting with polymer matrix, and their contribution to gas separation (GS) performance. In this study, a facilitated transport-cum-solution diffusion-based chitosan/2-Amino-3-phenylpropanoic acid, also called phenylalanine, grafted and blended membranes were prepared via the solution casting method for gas separation (GS) application. The fabricated membranes were systematically investigated to characterize their chemical, mechanical and thermal stabilities using various characterization techniques. The GS tests with 20% CO2 and 80 % N2 mixed gas were conducted at 85 °C and 2.21 bar feed pressure. The results suggest that the grafting and blending of phenylalanine (Phe) with the chitosan (CS) matrix boosted the CO2 permeance and CO2/N2 selectivity of the fabricated membranes, respectively, when compared to the bare CS membrane under similar experimental conditions. The obtained results are validated by calculating the activation energy of permeability from the Arrhenius plots for both grafted and blended membranes. The highest obtained CO2 permeance was 106 GPU in the Phe-grafted-CS membrane, and optimal selectivity was 97 in the 20 wt% Phe-blended-CS membrane. The stability tests were also conducted for both types of membranes. The results suggest that chemical grafting showed more stable results than physical blending when the membranes were tested for a long run of almost 400 h.