Hydrophilic polyvinyl alcohol coating on hydrophobic electrospun nanofiber membrane for high performance thin film composite forward osmosis membrane

In this study, the hydrophilic property of polyvinyl alcohol (PVA) was utilized to improve the hydrophilicity and mechanical strength of electrospun polyvinylidene fluoride (PVDF)-supported thin film composite (TFC) forward osmosis (FO) membranes. The PVDF nanofiber support was modified with PVA via dip coating and acid-catalyzed crosslinking with glutaraldehyde prior to formation of polyamide active layer on the support via interfacial polymerization. The influence of PVA modification on the morphology and physical properties of PVDF support was evaluated through several characterization techniques while the flux performance was assessed using lab scale FO membrane unit. The fabricated PVA-modified TFC FO membranes exhibited high hydrophilicity, porosity, and mechanical strength. FO performance tests reveal excellent flux performance (34.2 LMH using 1 M NaCl and DI water as draw and feed solution, respectively) and low structural parameters (154 pm) of the PVA-modified TFC FO membrane. Dip coating of the nanofiber support in PVA is therefore a simple and effective method for the improvement of PVDF support hydrophilicity to fabricate high performance TFC FO membranes.