Facile approach for novel TFC-NF membranes preparation using water soluble poly(vinyl alcohol-co-styrenesulfonic acid) and their characterizations

This research article first time reports the concept of thin film composite (TFC) membranes preparation using novel functional copolymer based on poly(vinyl alcohol-co-styrenesulfonic acid) (PVA-co-SSA). Polysulfone ultrafiltration membrane was coated by applying PVA-co-SSA solution via eco-friendly method. The selective coating layer was crosslinked by glutaraldehyde (GA) aqueous solution. The effects of PVA-co-SSA and GA solution concentrations used for TFC membranes preparation were evaluated to study the membranes' characteristics. Infrared and Raman spectroscopy was used to confirm the structural characteristics of composite membranes. The resultant TFC membranes were found hydrophilic (exhibited water contact angle in the span of 41 & DEG; to 60 & DEG;) and possessed a smooth surface having surface roughness ranging from 20.9 to 26.3 nm with the selective layer thickness in the range of 123 to 276 nm. Membrane exhibited maximum water flux of 32.78 l m(-2) h(-1) at when operated in cross-flow cell at 0.69 MPa; at same pressure the membrane gave 74.8% rejection of MgSO4 when fed with 1000 ppm solution of MgSO4; while NaCl rejection of membranes was in the range of 33.75 to 54% when tested using 2000 ppm NaCl feed solution supplied at operating pressure of 1.7 MPa. The trade-off relationship between membrane solute rejection and flux was observed, and composite membranes showed higher rejection of bivalent salt i.e. MgSO4 compared to monovalent salt i.e. NaCl.

Automated summary

This research introduces the concept of thin film composite (TFC) membranes prepared using a novel functional copolymer, PVA-co-SSA. A polysulfone ultrafiltration membrane was coated with a PVA-co-SSA solution, which was then crosslinked with glutaraldehyde (GA) aqueous solution. The characteristics of the TFC membranes were evaluated based on the concentrations of PVA-co-SSA and GA solution used for preparation. The composite membranes exhibited a hydrophilic and smooth surface, with a thickness of the selective layer ranging from 123 to 276 nm. The membranes showed high rejection of MgSO4 (74.8%) and moderate rejection of NaCl (33.75% to 54%) at different operating pressures.