Cyrene-Enabled Green Electrospinning of Nanofibrous Graphene-Based Membranes for Water Desalination via Membrane Distillation

Abstract

High-performance and sustainable membranes for water desalination applications are crucial to address the growing global demand for clean water. Concurrently, electrospinning has emerged as a versatile manufacturing method for fabricating nanofibrous membranes for membrane distillation. However, widespread adoption of electrospinning for processing water-insoluble polymers, such as fluoropolymers, is hindered by the reliance on hazardous organic solvents during production. Moreover, restrictions on industrial solvents are tightening as environmental regulations demand greener alternatives. This critical challenge is addressed here by demonstrating, for the first time, the fabrication of nanofibrous electrospun membranes of PVDF-HFP, poly(vinylidene fluoride)-co-hexafluoropropylene using a renewable, environment- and user-friendly solvent system containing Cyrene (dihydrolevoglucosenone), dimethyl sulfoxide, and dimethyl carbonate. The same solvent system was further used to produce nanocomposite graphene oxide (GO) and graphene nanoplatelet (GNP)-containing nanofibrous electrospun membranes. When tested for water desalination via membrane distillation, these membranes either outperformed or matched the performance of those produced with hazardous organic solvents, achieving salt rejection rates of >99.84% and long-term stability. The economic viability of the green solvent system was further validated through Monte Carlo simulations. This work demonstrates the potential to move fluoropolymer electrospinning from dimethylformamide-based systems to greener alternatives, enabling the consistent production of high-quality nanofibrous membranes. These findings pave the way for more sustainable manufacturing practices in membrane technology, specifically for water desalination via membrane distillation.