Sustainable fabrication and pervaporation application of bio-based membranes: Combining a polyhydroxyalkanoate (PHA) as biopolymer and Cyrene(TM) as green solvent

Within the prospect to develop a more sustainable solution for the membrane fabrication sector, this work aims to investigate a new combination of bio-based materials, including a polyhydroxyalkanoate (PHA) as a polymer and Cyrene(TM) as a solvent, for the phase inversion process. The herein studied poly(hydroxybutyrate-cohydroxyvalerate) (PHBHV) is a microbial biopolymer with excellent biocompatible, biodegradable and solvent resistance properties; while Cyrene(TM) is a non-toxic, biodegradable and renewable alternative to most of the traditionally used polar aprotic solvents. Several parameters of the phase inversion process were studied in order to identify the different membrane microstructure possibilities and thus their final performances. The various studied process parameters include the evaporation time before coagulation, the use of different traditional and green additives, the concentration of polymer and additives into the dope solution and the molecular weight of the additives. Polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) and an epoxidized broccoli vegetable oil (EBO) were successfully used as pore former agents for these membranes. Developed membranes were fully characterized in terms of morphology, topography, surface wettability, pore size, porosity, thermal degradation, mechanical resistance and stability. After all, membranes exhibiting different architectures (from porous to dense) were obtained. In order to prove their applicability, dense membranes were finally successfully applied in pervaporation (PV) for the separation of an organic/organic azeotropic mixture.