Incorporation of a novel Ag–Cu@ZIF-8@GO nanocomposite into polyethersulfone membrane for fouling and bacterial resistance

Abstract

A series of nanocomposite membranes, Ag@ZIF-8@GO/PES, Cu@ZIF-8@GO/PES and Ag–Cu@ZIF-8@GO/PES, were fabricated via phase inversion method. These were characterized using scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDS), X-ray photoelectron microscopy (XPS), atomic force microscopy (AFM) and water contact angle (WCA) measurements. The SEM images revealed an increase in pore density with the incorporation of the hydrophilic GO, porous ZIF-8 and the ZIF-8@GO composite as well as those containing Ag and Cu. The presence and the distribution of the nanoparticles onto the membranes were confirmed by XPS, EDS and elemental mapping. The composite membranes containing AgNPs showed excellent antibacterial properties against Escherichia coli. Furthermore, the antifouling properties of the composite membranes were assessed by filtration of bovine serum albumin (BSA), as a model foulant. An increased flux recovery ratio for the composite membranes (78–97%) was observed in comparison to that of the pristine PES membrane (43%). The flux recovery ratios of the nanocomposite membranes were maintained for more than six cycles showing their recyclability and fouling resistance. The observed metal leaching from the composite membranes was minimal and far less than the WHO threshold. The incorporation of the composite fillers led to concurrent improvement in the bacterial growth inhibition and protein fouling resistance boding well for application in water treatment.