Corrosion resistance of ZrO₂ nanofiltration membranes

A stable ZrO₂ polymeric sol was synthesized through a sol-gel method using zirconium n-propoxide as precursor. Disk α-Al₂O₃ supported mesoporous γ-Al₂O₃ membrane with an average pore size of 5-6 nm was used as support for nanofiltration membranes deposition. Defect-free ZrO₂ nanofiltration membranes superimposed on these supports were fabricated via dip-coating method followed by drying and calcination. The chemical stabilities of supported ZrO₂ nanofiltration membranes were detemined by static corrosion tests. Results showed that unsupported ZrO₂ membranes calcined at 350°C and 400°C were found to be chemically stable in a pH window of 1-13. Supported ZrO₂ nanofiltration membrane calcined at 400°C was found to be chemically stable in a window of pH=2-12. While the membrane calcined at 350°C showed reduced PEG-rentention properties after immersed in pH=12 and 2 solutions. The result can be attributed to the amorphous phase presented in zirconia separation layer as well as the chemical instability of the γ-Al₂O₃ layer beneath.