Membranes for the pervaporation of solvent azeotropes: from molecular to process design

The separation of organic solvents in the chemical industry is highly energy-intensive, particularly when dealing with azeotropic solvent mixtures for which conventional distillation is ineffective. Addressing the growing environmental concerns, waste generation, and high energy consumption associated with solvent lifecycles requires the development of highly permeable and selective membranes for sustainable solvent recovery. Pervaporation represents a promising, energy-efficient alternative. In this work, we report the fabrication of thin-film composite membranes exhibiting outstanding permselectivity for toluene–methanol mixtures, achieved through interfacial polymerization. The polarity of the nanofilms was enhanced through the incorporation of various hydrophilic amine-functionalized structures. By precisely overcoming the trade-off between selectivity and permeability observed in previously reported polymeric pervaporation membranes. The highest separation performance was attained by combining interfacial polymerization with post-functionalization using polyethyleneimine, yielding an impressive separation factor of 642 and a flux of 4.1 kg m−2h−1. This corresponds to 800 % improvement in selectivity compared to the control polyamide membrane for a 10 wt% methanol and 90 wt% toluene mixture. Long-term stability tests demonstrated the remarkable durability of the post-functionalized membranes, with minimal permeance variation in the methanol concentration of the permeate (∼1.5 %). Process simulations confirmed that integrating pervaporation with distillation enables significantly more energy-efficient and cost-effective operations, underscoring the potential of the developed membranes for polar-non-polar solvent separation applications. An energy balance analysis further highlighted the substantial energy efficiency gains achievable with hybrid pervaporation-distillation systems compared to conventional methods. © 2025 Elsevier B.V.