Polyamide thin-film nanocomposite membranes with graphene oxide nanosheets: Balancing membrane performance and fouling propensity

Reverse osmosis (RO) is the fastest growing desalination technology but still suffers from the permeability selectivity tradeoff of polymeric membranes and the vulnerability of polyamide thin film composite (TFC) membranes to fouling. Membranes incorporating graphene oxide (GO) sheets in the polyamide layer have the potential to address these limitations by providing antifouling and molecular sieving capacities. However, these two properties of GO-based thin film nanocomposite (TFN) membranes originate from different features of GO and optimal TFN composition may differ when designing for improved permeability or fouling resistance. In this study, we evaluated the effect of incorporating GO sheets in the polyamide active layer of TFN membranes on their separation performance and fouling resistance. Increasing the GO loading in TFN membranes increased the antifouling and antimicrobial properties of TFN membranes. On the other hand, a small increase in membrane permeability was observed at low GO loading and decreased with increasing GO content in the active layer. Therefore, the results of this study emphasize the trade-off that exists between improved performance and reduced fouling propensity and the benefits of GO appear higher as an antimicrobial and antifouling additive than a permeability enhancer in TFN membranes.