Preparation and characterization of green polylactic acid (PLA) membranes for organic/organic separation by pervaporation

Membrane science, in the context of the growing attention towards the preservation and protection of the environment, has an emerging role as a very well-recognised eco-friendly technology. In order to meet the complete concept of sustainability, however, greener strategies still need to be put in place regarding the preparation of the membranes. Polylactic acid (PLA) green flat sheet membranes were prepared using ethyl lactate as a green solvent and water as a non-solvent, for the first time. The morphology, thickness, contact angle, mechanical properties, FTIR and degree of swelling were determined for studying the properties of the produced membranes. A systematic study was performed testing PLA membranes in pervaporation (PV) for the separation of methanol (MeOH)/methyl tert-butyl ether (MTBE) azeotropic mixture evaluating their performance by varying feed temperature and vacuum degree. The findings revealed that the membrane morphology changed from finger-like to spongy-like and finally to dense-like structure by acting on the evaporation time (ET) during the preparation with an improvement in the overall mechanical properties. The PLA dense membrane produced with an ET of 7min was successfully tested in PV exhibiting a preferred permeation towards MeOH with a highest selectivity value of more than 75. An Arrhenius-type dependence between flux and temperature was found.