High-performance and durable pressure retarded osmosis membranes fabricated using hydrophilized polyethylene separators

A high-performance and durable thin-film composite (TFC) pressure retarded osmosis (PRO) membrane was fabricated using a polyvinyl alcohol (PVA)-coated polyethylene (PAPE) support via toluene-assisted interfacial polymerization (TIP). The PVA coating uniformly hydrophilized the extremely thin (~8 μm) polyethylene (PE) support with a highly porous structure while marginally deforming the support structure, resulting in a very low structural parameter (~235 μm). The TIP process produced a polyamide selective layer with remarkably higher water permeability (~8.78 L m⁻² h⁻¹ bar⁻¹) than those of commercial HTI membranes (0.56–1.40 L m⁻² h⁻¹ bar⁻¹). Furthermore, despite its extreme thinness, the PAPE-supported TFC (PAPE-TFC) membrane had higher mechanical properties than the commercial membranes owing to the superior mechanical strength of its PE support. Hence, the PAPE-TFC membrane achieved an unprecedentedly high power density of ~35.7 W m⁻² at an applied pressure of 20 bar using a deionized water feed solution and a 1.0 M NaCl draw solution, which significantly outperformed commercial and any other reported lab-made PRO membranes. The mechanically robust PAPE-TFC membrane also enabled stable long-term PRO operation under high pressure conditions.