Fabrication and characterization of anti-fouling and anti-bacterial Ag-loaded graphene oxide/polyethersulfone mixed matrix membrane

Partially reduced graphene oxide/Ag nanocomposite (rGO/Ag) was fabricated via a green and facile method, from graphite oxide, AgNO₃ as a precursor of Ag⁰, and sodium citrate as a reducing and stabilizing agent. The synthesized rGO/Ag nanocomposite was characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy techniques (SEM). The influence of rGO/Ag nanocomposite as a new nanofiller on the preparation of polyethersulfone (PES) mixed matrix membranes was evaluated in the cases of permeation performance, hydrophilicity, anti-fouling and anti-bacterial properties. Water flux of the mixed matrix membranes was increased up to 0.2wt% rGO/Ag, reaching to 429.8 (kg/m²h), and then reduced. The anti-bacterial activities of rGO/Ag mixed matrix membranes were investigated using Gram-negative bacteria of Escherichia coli and Pseudomonas aeruginosa, and Gram-positive bacteria of Staphylococcus aureus. The amount of Ag⁰ in the surface of GO sheets was about 34.24wt%. Addition of rGO/Ag nanosheets induced anti-bacterial properties to the membranes, leading to the increase in the zone of inhibition. The flux recovery ratio (FRR) study of the membranes using bovine serum albumin (BSA) solution revealed that 0.2wt% rGO/Ag membrane had the best fouling resistance with the FRR value of 67.2%.