Polylactic acid-based membranes for CO2 separation

Today, there is a growing attention toward the adoption of green membrane materials based on biopolymers, which represents a starting point to exploit raw feedstocks in the viewpoint of a carbon footprint [1,2]. In particular, biogas represents a renewable source, from which bio-methane could be extracted separating CO2 and other byproducts to constitute a viable and green alternative to the exploitation of natural gas. Biogas is known to be constituted of various compounds: CH4 (40-70 vol%), CO2 (30-60 vol%) and trace amount of NH3, H2O and H2S. The aim of this work focuses on the preparation and characterization of polylactic acid (PLA) dense membranes via solvent evaporation technique to be used in gas separation and, particularly, for CO2/CH4 separation. The selected membranes are based on 10wt% of biopolymer concentration and the membrane thickness results to be ~ 30 ?m. The preliminary results showed interesting performance at room temperature in terms of CO2 permeability (> 10 Barrer) and CO2/CH4 ideal selectivity (~ 220), well above the related Robeson's upper bound, Figure 1.