Nanoparticle-templated polyamide membranes for improved biofouling resistance

Applying an interlayer of nanomaterial to the support layer during interfacial polymerization results in a change in the polyamide (PA) properties that can be leveraged to improve the performance of desalination membranes. While studies have shown that permeability and selectivity can be increased using an interlayer of nanomaterials, the potential of using this approach to improve the PA properties relevant for fouling and biofouling is less understood. In this study, we investigated how using an interlayer of alumina nanoparticles (Al-NP) to template the interfacial polymerization process affects the fouling and biofouling propensity of thin film composite membranes. Performance was measured by static bacteria and protein deposition assays as well as dynamic reverse osmosis biofouling experiments. The low and medium Al-NP loadings were found to reduce bacteria and protein adhesion while, at a high Al-NP loading, both bacteria and protein adhesion increased. A similar trend was observed in dynamic fouling conditions, with the low and medium Al-NP loadings experiencing less flux decline and lower biofilm volume on the membrane compared to the control or high Al-NP loaded membrane. The superior antifouling properties of these membranes were correlated with the change in the free energy of cohesion of the PA layer formed on the Al-NP interlayer. Our results demonstrate that using an interlayer of Al-NP can alter the PA surface chemistry in a way that reduces membrane fouling; however, there is a threshold loading of Al-NP beyond which fouling propensity increases due to the effect of Al-NP agglomeration on the PA morphology. These results provide useful insights into how NP can be added to the interlayer during interfacial polymerization to improve the performance of desalination membranes.