Membranes from bio-based poly(ethylene furanoate) and natural solvents

Abstract

Replacing fossil materials with renewable bio-based alternatives is a pivotal strategy to make the membrane manufacturing industry more sustainable in alignment with the UN Sustainable Development Goals. Poly(ethylene furanoate) (PEF) is a biopolymer synthesized from 2,5-furan dicarboxylic acid, a natural monomer that can be derived from lignocellulosic biomass, with the potential to replace fossil polymers across various fields. However, its high chemical stability makes solubilization challenging, and currently, the most common solvent choices for this purpose are fossil-based solvents such as trifluoroacetic acid (TFA) and hexafluoro-2-propanol. In this work, we introduce a bio-based solvent alternative to process PEF into porous membranes consisting of a deep eutectic system comprising the natural solids thymol and vanillin. The resulting ultrafiltration membranes exhibited competitive performance for fruit juice clarification. A life cycle assessment showed a lower Global Warming Potential, human toxicity, and fossil depletion for the proposed fabrication protocol compared to a fossil-based counterpart, poly(ethylene terephthalate) solubilized in TFA. We identified the nonsolvent production and waste treatment as the primary contributors to the environmental impact of PEF membrane production, and demonstrated the environmental benefits of mitigation strategies such as waste recycling, energy recovery, and the use of a bio-based nonsolvent. Our findings expand the alternatives for more sustainable PEF processing in solution, and demonstrate the potential of PEF as a high-performance polymer for membrane separations.