Upcycling End-of-Life Polyvinylidene Fluoride Membranes into Reverse Osmosis Membranes for Sustainable Water Purification

Membrane technology has been increasingly applied in water purification to address global water scarcity. However, commercial membranes inevitably reach the end-of-life (EoL) after long-term operation, which constrains the sustainability of membrane technology. Herein, we demonstrated the feasibility of upcycling real EoL poly(vinylidene fluoride) (PVDF) microfiltration (MF) membranes into reverse osmosis (RO) membranes with higher separation precision via the interfacial polymerization (IP) reaction. We highlighted that the EoL MF membrane, with a fouling-induced narrowed pore size and relatively hydrophobic properties, is preferred for upcycling. The resultant upcycled RO membrane exhibited a satisfactory NaCl rejection (98.6 ± 0.4%) with favorable water permeance (2.3 ± 0.7 L m-2 h-1 bar-1), comparable to the performance of commercial RO membranes. Real wastewater treatment evaluations confirmed the membrane stability and permeate safety. Life-cycle assessment and techno-economic analysis showed that this upcycling process promises environmental and economic benefits, potentially reducing CO2-eq emissions by 18.6% and costs by 76.5%-92.2% compared with the conventional membrane approach. This proof-of-concept study paves the way for creating a closed eco-loop of membrane recycling for sustainable water purification.