Sulfonated polyethersulfone membrane doped with ZnO-APTES nanoparticles with antimicrobial properties

Abstract

In an attempt to mitigate membrane biofouling, the main limiting factor in membrane technology, ultrafiltration polyethersulfone (PES) membranes doped with zinc oxide nanoparticles (NPs) providing antimicrobial properties were fabricated. Synthesis of chlorsulfonated polyethersulfone (SPES-Cl) was based on modification of PES through sulfonation, followed by chlorination of -SO3H groups. The ZnO NPs were functionalized by (3-aminopropyl)triethoxysilane that enabled covalent bonding to polymer matrix, which was proved by XPS analysis. The membranes were examined for changes in permeability, antimicrobial properties, and leaching of ZnO NPs. Membrane with surface-functionalized ZnO NPs displayed permeability of ca. 260 L m−2 h−1 bar−1, comparable to the reference, while membrane doped with unmodified ZnO NPs exhibited permeability ca. 50 L m−2 h−1 bar−1. Membranes with ZnO NPs displayed antimicrobial properties, with unmodified ZnO NPs exhibiting inhibition zone of 2–3 mm for S. aureus and that for surface-functionalized ZnO NPs < 0.5 mm. This corresponds with leaching, 25.9% of unmodified ZnO NPs leached from membrane compared with 5.8% for the covalently-bonded ZnO NPs.