Preparation and Ions Retention Properties of TiO_2 Nanofiltration Membranes

A stable TiO2 Sol with a mean particle size of 1.2 nm was synthesized with titanium isopropoxide as a precursor through polymeric Sol-Gel route.Disk-Al2O3 supported mesoporous-Al2O3 membrane with mean pore size of 3 nm was used as support for nanofiltration membranes deposition.Defect-free TiO2 nanofiltration membranes superimposed on these supports were fabricated via dip-coating method followed by drying and calcination.The effect of calcination temperature on properties of unsupported TiO2 membranes(powders) as well as supported TiO2 nanofiltration membranes was studied in detail.The MWCO,mean pore size and pure water flux of TiO2 nanofiltration membrane calcined at 350℃ were 890,1.5 nm and 5.3 L/(m2·h)(at 8×105Pa,20℃),respectively.Ions retention properties of Ti-350 nanofiltration membrane towards five solutions like NaCl,CaCl2,Na2SO4,MgCl2 and Ni(NO3)2 were characterized.Under a pH value of 4.0 and transmembrane pressure of 5.0×105Pa,the retention properties of Ti-350 membrane towards CaCl2 and MgCl2 solutions reach maximum values of 96.5% and 92.8%,respectively.