Effect of silica on flexibility of yttria-stabilized zirconia nanofibers for developing water purification membranes

The development of flexible ceramic nanofibers has attracted much attention because they may be able to overcome the intrinsic brittleness of ceramics and thus be applied towards air/water filtration media. Yttria-stabilized zirconia/silica (YSZ/silica) nanofibers with excellent flexibility could be prepared through (1) sol-gel, (2) electrospinning, and (3) calcination processes. Our research focused on the effect of ceramic precursor concentrations [tetraethyl orthosilicate (TEOS) and zirconium (IV) propoxide (ZrP)] on improving the flexibility of YSZ/silica nanofibers. By adjusting the TEOS and ZrP concentrations, two major parameters (grain size and fiber diameter, respectively) can be controlled. It was consequently revealed that smaller grain size and larger fiber diameter could increase the flexibility of YSZ/silica nanofibers. In addition, flexible YSZ/silica nanofibers successfully performed as microfiltration (MF) membranes, while exhibiting high pure water permeability and a high rejection rate (%) for polymeric nanoparticles.