TiO2-Enhanced Mixed Matrix Membranes for Water Purification

TiO₂ nanoparticles have shown potential in the removal of volatile organic compounds and pharmaceuticals from wastewater by heterogeneous photocatalysis.  While the photooxidative effect of TiO₂ nanoparticles under UV light has been widely studied and seen many improvements, the issue of immobilization of the nanoparticle catalyst remains an obstacle to the realization of widespread practical application.  Additionally, components of the degradation reaction- namely the UV source itself and the highly reactive species produced in water- cause oxidation of the matrix when TiO₂ is immobilized in an organic membrane.  Here we present information on the effect of TiO₂ nanoparticles on polymer degradation under UV irradiation in polyethersulfone and cellulose acetate mixed matrix membranes.  The influence of the addition of TiO₂ on the morphology of the membrane will be presented, including porosity, thickness, and nanoparticle dispersion.  Properties, including contact angle, permeability, and nanomechanical properties, of the unloaded and nanoparticle-loaded membranes will be compared before and after UV exposure.  Quartz crystal microbalance analysis will show the stability of the materials under ultraviolet irradiation.  In addition, we will present preliminary results on the incorporation of a UV-resistant silicon-based preceramic polymer as a novel membrane modifier.