Graft copolymerization of zwitterionic monomer on the polyethersulfone membrane surface by corona air plasma for separation of oily wastewater

Abstract In this study, we investigated the modification of polyethersulfone (PES) membranes surfaces by grafting of SBMA zwitterionic monomers as a sublayer added via corona-induced graft co-polymerization. The objective was to reduce fouling and subsequently increase permeate flux for the separation of water-oil emulsions. Therefore, effects of graft polymerization conditions on surface properties were investigated, and the impact of SBMA grafting yield on contact angle (CA) and flux recovery ratio (FRR) for long-term antifouling properties were studied. SEM, XPS, ATR-FTIR, and CA measurements were employed to characterize unmodified and modified membranes and confirmed that SBMA brushes were successfully grafted onto PES membranes. The results revealed a remarkable enhancement of water-oil flux in the modified membranes (more than 1100%) at grafting temperature of 65°C and grafting yield of 0.489 mg/cm2 without any significant effect in the oil rejection value followed by FRR amount of 87.5%. Moreover, immersing the grafted membranes into deionized water for 30 days resulted in a 10% reduction in flux and a slight increase in CA, which proved the stability of membrane surface over a long period of operating time especially in industrial applications.