Doping polysulfone ultrafiltration membrane with TiO₂-PDA nanohybrid for simultaneous self-cleaning and self-protection

To prepare an ultrafiltration membrane with simultaneous self-cleaning and self-protection abilities, TiO₂-polydopamine (PDA) nanohybrid are facilely prepared and used to functionalize polysulfone (PSf) membrane matrix. In the TiO₂-PDA nanohybrid, PDA spheres acts as an adhesive substrate to hold densely covered photocatalytic TiO₂ nanoparticles, and also serves as a free-radical scavenger to protect PSf membrane against the damage by free radicals produced by TiO₂ during UV exposure treatment. The spherical-shaped TiO₂-PDA can be easily doped into PSf membrane via phase inversion method, which allows the hydrophilic TiO₂-PDA spheres migrating to the hydrophobic PSf surface and benefiting the antifouling ability. As a result, the TiO₂-PDA/PSf hybrid membrane exhibits excellent overall performances in separation efficiency, remarkable self-cleaning property and performance stability under UV irradiation, in comparison with PSf and TiO₂/PSf membrane. The influence of TiO₂-PDA content on the membrane properties is also investigated, and it is found the hybrid membrane with 0.8 wt% TiO₂-PDA possesses the optimal performance.