Polyethersulfone ultrafiltration membrane modified with polyamic acid- stabilized silver nanoparticles for enhanced filtration performance and antibacterial effects

Developing ultrafiltration (UF) membranes with excellent anti-biological fouling and overcoming the hydrophobicity of membrane material itself has been a major challenge. While exposing a major drawback of being unstable and easily lost from the membrane, silver nanoparticles (AgNPs) are still used as bactericidal substances in membranes. Polyamic acid (PAA) is a flexible hydrophilic polymer that exhibits strong complexing ability and considerable steric hindrance effect on metal cations. Herein, using PAA as a stabilizer to modify the size and dispersion of silver nanoparticles (AgNPs), we developed a polyethersulfone (PES) UF membrane featuring both hydrophilic and antibacterial dual functions. The AgNPs in the as-prepared membrane were small in size (around 3–10 nm) and highly dispersed in the membrane, exhibiting highly efficient antibacterial ability with 96.82% and 98.29% inhibition towards Escherichia coli and Staphylococcus aureus , respectively. Meanwhile, the partially covered AgNPs by PAA and the high surface energy made them less susceptible to lose in the membrane. The developed membrane retained about 4.5 times more AgNPs than the original membrane for the same membrane area. Moreover, the favorable hydrophilic and pore structure endowed the membrane with high water flux and acceptable rejection of bovine serum albumin (BSA). The PES/PAA-Ag membrane exhibited an excellent water flux, which was 421.47 (L/m 2 ·h) under 1 bar pressure, about 1.4 times of PES and 3.4 times of PES-Ag membrane (with a high BSA rejection, around 90%). This work provided a reference for the development of hydrophilic and antimicrobial membranes, as well as having considerable potential practical value.