Preparation and characterization of PVDF/TiO2 organic-inorganic composite membranes for fouling resistance improvement

In this study, a polyvinylidene fluoride (PVDF) ultrafiltration (UF) membrane was modified by dispersing nano-sized titanium(IV) oxide (TiO2) particles in a PVDF solution. PVDF flat-sheet membranes were fabricated by a phase inversion method. Nonwoven fabric and PET film were used as the support layer. This study investigates the effect of TiO2 nanoparticles, type of coagulants, and support layers on membrane permeability. The experimental result indicates that the membrane surface can be modified by adding TiO2 nanoparticles, coagulant solvent compositions, and support materials. PVDF membrane fouling was reduced by changing the membrane surface from hydrophobic to hydrophilic after TiO2 addition. PVDF membranes immersed in pure water coagulation bath solution revealed typical large finger-like structures; however, when water/isopropanol mixtures were used as the coagulant solvent, PVDF membranes exhibited sponge-like structures instead of finger-like structures. By using the PET film (instead of non-woven fabric) as the support layer, excessive penetration of the cast solution into the support layer could be prevented. However, a dense PET film obstructed the exchange of polymer solution and coagulation bath solution and therefore small pores were formed due to a slow membrane formation process. (C) 2009 Elsevier B.V. All rights reserved.