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

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 degrees C and grafting yield of 0.489 mg/cm(2) 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.

Automated summary

By grafting SBMA zwitterionic monomers onto PES membranes using corona-induced graft co-polymerization, the water-oil flux was significantly enhanced (over 1100%) without affecting oil rejection. The stability of the modified membranes over a long period was confirmed through a 10% reduction in flux after immersing in deionized water for 30 days. This study demonstrates the potential for practical applications in industrial settings.