Gas Permeation Performance of Poly(lactic acid) Asymmetric Membrane for O₂/N₂ Separation

Membrane gas separation has been one of the most favorable techniques used in industry due to its efficiency and low operating cost. One of the main problems in using membrane in gas separation is the non-biodegradable nature of the membrane material. In this study, PLA membrane was fabricated for oxygen/nitrogen separation system. The dope solution was prepared by using dichloromethane as a solvent with different concentration of 15, 17.5, 20 and 25 wt%. The membrane was cast at a fixed casting speed and solvent evaporation time of 0.0413 ms⁻¹ and 60 s, respectively by using pneumatically-controlled casting system via dry/wet phase inversion technique. The prepared membrane morphology, mechanical strength and gas permeation performance was characterized using scanning electron microscope (SEM), tensile testing machine and soap bubble meter, respectively. Based on SEM result, the increase in dope solution concentration was proven to decrease the membrane porosity and increase its compactness that leads to the improvement of membrane gas permeation performance and mechanical strength. However, the further increase of concentration led to membrane brittleness with low elasticity causing the membrane become hard to handle for further testing.