Enhanced Bioethanol Separation via Thymol-Based DES-Integrated Membranes Derived from Waste PET Bottles

Recycled polyethylene terephthalate (rPET) membranes offer a promising sustainable alternative, but their low separation efficiency limits their viability for bioethanol recovery via pervaporation. To address this challenge, we introduce a novel hydrophobic deep eutectic solvent (HDES) to enhance the membrane performance. Using the conductor-like screening model for realistic solvents (COSMO-RSs), we identified an optimized HDES with superior affinity for ethanol, ensuring an improved pervaporation performance. The incorporation of HDES into rPET membranes was validated through FTIR, XRD, WCA, SEM, and AFM analyses, confirming the enhanced surface properties. The modified membranes exhibited a remarkable increase in bioethanol flux, reaching 2.03 kg m^–2 h^–1, while maintaining a high separation factor of 22.84. These findings highlight the potential of green-solvent-assisted membrane engineering to enhance bioethanol separation, offering a cost-effective and environmentally responsible approach for waste valorization and renewable energy applications.