Near Azeotropic Ethanol–Water Mixture Pervaporation Through a Polyvinyl Alcohol Membrane: A Parametric Study on Process Efficiency

The goal of this study was to explore how different operating parameters influence the performance of a polyvinyl alcohol (PVA) membrane in pervaporation for separating ethanol-water mixtures. Specifically, the focus was on understanding how variations in feed composition, temperature, and permeate pressure affect the separation efficiency. The study aimed to provide a range of operating conditions that offer a balance between maximizing both the purity and quantity of ethanol. This was achieved through statistical models, which were generated by simulating the pervaporation process under various conditions using COMSOL Multiphysics^® 6.3 and following a Box-Behnken design. It was found that similar operating conditions (temperature ~100 °C; pressure ~4-5 kPa) are suitable for both kinds of mixtures near azeotrope, with higher water content (~0.15 mass fraction) and lower water content (~0.05 mass fraction) obtaining very high recuperation degrees (generally above 99%). For more concentrated solutions (lower water content), it was possible to obtain optimal trade-off solutions (separation degree vs. retentate enrichment in ethanol), even at lower temperatures (~80 °C).