Preparation and Properties of Sulfonated Graphene–Modified Ultrafiltration Membranes

Abstract

The unique benefits of membrane therapy technology make it a popular choice. However, polyvinylidene fluoride (PVDF) and polysulfone (PSF) can readily become contaminated in practical applications. Therefore, in this study, sulfonated graphene oxide (SGO) was doped as an additive at various concentrations, along with dopamine (DA) and silver (Ag) as surface modifiers, to prepare a DA-Ag–modified SGO/PSF/PVDF ultrafiltration membrane with enhanced antipollution performance. The water flux, mechanical strength, and other characterization tools were then applied to analyze the hydrophilicity and structural composition of the membrane. The flux measurement demonstrated that SGO had better hydrophilicity and contamination resistance than graphene oxide (GO). The membrane exhibited the best performance when SGO was added at 0.3 g in the casting solution. The result showed a water flux of 675.80 L m−2 h−1, which was 1.27 times greater than that of the neat membrane. Furthermore, the retention of bovine serum albumin (BSA) was 96.00% and the flux recovery was 85.60%. The antibacterial rate against Escherichia coli and Staphylococcus aureus was up to 97.96% and 96.20%, respectively. Interestingly, the membrane still implied a sustainable antimicrobial effect after 90 days, demonstrating its long-lasting bacteriostatic properties. In previous studies, polyvinylidene fluoride was widely applied in the fabrication of ultrafiltration membranes. However, the membrane’s lifespan was shortened because of its hydrophobicity nature. Graphene oxide has been studied in the field of hydrophilic modification of membranes. However, the poor dispersion of its particles in the ultrafiltration membrane has affected the lifespan and application efficiency of the membrane’s application. Therefore, to raise the utilization efficiency of particulate matter, graphene oxide was sulfonated in this study. At the same time, it was found that combining membrane blending/doping with membrane surface deposition, instead of relying on a single modification method, can enhance both inside and outside antibacterial properties of the membrane, as well as other membrane properties. Moreover, in the research, the optimal concentration of the modified material was selected by adjusting the structure of the ultrafiltration membrane. The prevention of particle agglomeration through sulfonation is the innovative aspect of this study, offering a new research direction for future industrial utilization of graphene oxide and ultrafiltration membranes.