Modification of PES membrane with Ag–SiO2: Reduction of biofouling and improvement of filtration performance

• Ag/SiO2 nanocomposite materials as an excellent antimicrobial agent
• Ag–SiO2/PES membrane exhibits magical anti-bacterial and anti-biofouling properties.
• Ag–SiO2/PES membrane largely prevents silver loss.

Fouling is a critical problem in membrane filtration processes. Creating advanced membrane materials with antifouling properties is one of the practical strategies to reduce biofouling. To improve the antifouling performance and enhance the dispersion of silver in the membrane, the silver nanoparticle was deposited on the silica sphere surface to form Ag–SiO2. Ag–SiO2 nanocomposite polyethersulfone (PES) membranes were fabricated by phase inversion method. The effect of Ag–SiO2 content on the membrane performance was investigated. Surface and cross-section morphologies, hydrophilicity and permeability of the membranes were characterized by Scanning Electron Microscopy (SEM), contact angle measurement and filtration test, respectively. The results demonstrated that the prepared membranes showed a typical asymmetric structure and the contact angle of the membrane decreased from 67.7° to 52.6° with the increase of the Ag–SiO2 loading. The stability of the silver in the nanocomposite membranes was evaluated during the membrane fabrication and filtration. The anti-bacterial and anti-formation properties of the membranes were systematically studied with pure cultures of both Escherichia coli and Pseudomonas sp. and also with a mixed bacteria culture in an activated sludge bioreactor. The results showed that the prepared Ag–SiO2/PES membrane exhibited improved filtration performance and excellent anti-bacterial and anti-biofouling properties.