Preparation and Ni²⁺ retention property of mesoporous TiO₂ membrane

A stable TiO₂ sol with a mean particle size of 41 nm was successfully synthesized with titanium isopropoxide as precursor by a colloidal sol-gel route. Defect-free mesoporous TiO₂ membranes with a relative molecular mass cut-off (MWCO)<10000 were prepared on the α-Al₂O₃ disk with the mean pore size of 70 nm at a suitable sol viscosity via dip-coating for one time and subsequently calcined in the temperature range of 400-600°C, and then characterized. The effect of the calcination temperature on the properties of unsupported TiO₂ powders as well as the supported TiO₂ membranes was investigated. The results show that TiO₂ membrane with an average pore size of 4.7 nm and a MWCO of 8150 can be obtained after calcined at 400°C for 3 h. The filtering flux of pure water of this membrane is 30 L/(m²·h) at 0.8 MPa and 20°C. The retention ratio of membrane for Ni(NO₃)₂ solution reaches a maximum value of 95.14% under a pH value of 3.