Silver–PEGylated dendrimer nanocomposite coating for anti-fouling thin film composite membranes for water treatment

• Silver–PEGylated dendrimer nanocomposite was coated on thin film composite membrane.
• Bacterial attachment has been reduced by 99.8% after coating.
• Protein fouling is also significantly reduced.
• Protein-surface force was measured by AFM to explain the anti-fouling mechanism.

This study proposes a facile method to fabricate thin film composite (TFC) membranes with silver–polyethylene glycol PEGylated dendrimer nanocomposite coatings on the surface to reduce both bacteria and protein fouling in the sustainable water treatment processes. Interestingly, the surfaces of TFC membranes have been imparted with different functionalities such as carboxylic acid, amine, PEG or silver nanoparticles in the modification process, which provide useful platforms to compare the anti-fouling properties of the four kinds of functional groups. Significant improvements on hydrophilicity have been found after modifications. All modified membranes show reduced attachment of E. coli and bovin serum albumin (BSA). Among them, the silver–PEGylated dendrimer nanocomposite membrane is subjected to the least fouling by the maximum fouling reduction of 99.8%. In particular, as a unique strength of this study, AFM force measurements were performed on membrane surfaces to study the interactions between protein and different surfaces. The adhesion force between the amine-functionalized surface and the tip suggests that the electrostatic interactions between the amine-modified membrane is very strong, resulting in a fast initial deposition of proteins on the membrane surface. The adhesion forces for PEG and silver nanoparticle modified membranes are small, which well explain the lower protein fouling of the membranes.

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