Preparation of nanoparticle-embedded polysulfone ultrafiltration membranes and evaluation of the anti-biofouling property

In order to enhance the anti-biofouling ability, surface modification of polysulfone ultrafiltration membrane was performed by in-situ embedment of four types of nanoparticles-aluminum oxide (Al₂O₃), Linde type A zeolite (LTA), Linde type L zeolite (LTL) and Faujasite type X zeolite (FAU-X). The bare and the modified membranes were tested for the changes of structures and properties by conducting scanning electron microscope (SEM) observation, contact angle measurement and anti-biofouling test. SEM observation showed that in-situ embedment of the four different nanoparticles was feasible, which only changed the surface morphology but not the cross section of the membranes. Nanoparticles embedded on the surface increased the hydrophilicity of the membranes, resulting in the improvement of anti-fouling ability to organic matters. Anti-biofouling ability was also observed as the modified membranes were more resistant to the adhesion of E.coli on the membranes. There was no growth of E.coli on the areas covered by nanoparticles. Membrane UF-LTA and UF-LTL showed greater anti-adhesive ability than membrane UF-Al₂O₃ and UF-FAU-X. In general, zeolite LTA was an ideal material because they could better disperse on the membrane surface and remarkably improved the hydrophilicity and anti-adhesive ability of the membrane. However, zeolite LTA could not withstand the force of shear flow. In order to enhance the firmness stability of the incorporated zeolite LTA on the membrane surface, smaller particles would be preferred.