Self-assembly of TiO2 nanoparticles around the pores of PES ultrafiltration membrane for mitigating organic fouling

A novel method for preparation of polyethersulfone (PES) hybrid ultrafiltration (UF) membrane with sustainable antifouling property is developed. The highlight of this method is that the self-assembly of TiO2 nanoparticles around the pores of PES membranes was achieved during the formation of PES UF membrane via non-solvent induced phase separation (NIPS) process. The precursor (tetrabutyl titanate (TBT)) of TiO2 nanoparticles and triblock copolymer (Pluronic F127) were introduced to PES casting solution. The synchronous self-assembly of TiO2 nanoparticles around membrane pores and formation of PES polymeric membranes occurred during the NIPS process by controlling the hydrolysis and condensation of TBT. F127 plays an essential role in that its hydrophilic and hydrophobic segments have different affinity to the TiO2 nanoparticles and PES matrix respectively. TEM and SEM–EDX mapping confirm that TiO2 nanoparticles self-assemble around the pores of PES membranes. Water permeability of the resultant hybrid PES membranes was 4 times higher than that of neat PES membranes with a slight change of bovine serum albumin (BSA) rejection. The organic antifouling experiment, using BSA and humic acid (HA) as model foulants, manifest that the organic antifouling property of the PES hybrid membrane can be conspicuously enhanced. Importantly, the leaching of self-assembly TiO2 nanoparticles is restrained due to the interaction between the TiO2 nanoparticles and F127, which ensures a stable and sustainable antifouling activity of the membrane.