Modified wet chemical method synthesis of nano-ZrO₂ and its application in preparing membranes

In this study, pure tetragonal zirconia (t-ZrO₂), with an average size of approximately 7 nm, was prepared by a modified hydrothermal method using zirconium nitrate (Zr(NO₃)₄) as the zirconium source and glycerol as the additive. The effects of pH and glycerol content on the phase and morphology of the ZrO₂ were investigated, and the mechanism is discussed herein. The tetragonal phase gradually increased with an increase in pH, while the grain size of the powder gradually decreased. The effect of glycerol addition on the crystal phase of the powder was also investigated, and the results showed that the monoclinic phase gradually decreased with an increase in the amount of glycerol added. With a glycerol to zirconium molar ratio of 3:1, a single tetragonal phase was produced. In addition, a high-performance ZrO₂ ultrafiltration membrane was prepared by coating the inner surface of the tubular ZrO₂ membrane. The characterization results show that the thickness of the membrane was approximately 1.5 μm, the pure water flux was approximately 84 L m⁻² h⁻¹·bar⁻¹, and the molecular weight cut-off was approximately 7000 Da. The reproducibility of the high-performance ZrO₂ ultrafiltration membranes was also evaluated. It was found that the synthesised ZrO₂ membrane has high reproducibility and stability.