Triblock polymer template assisted sol–gel process for fabrication of multi-channel TiO2/ZrO2 ultrafiltration membrane

Multi-channel TiO2 membranes with an average pore size of 3.3 nm for ultrafiltration were fabricated via a template assisted sol–gel process, during which the triblock polymer L64 was used as a template to modify the properties of the sols and finally improved the separation performance of the membranes. To optimize the coating and sintering temperature, the relationships of viscosity–temperature curves of the sols and the thermal properties of the gels were investigated. The viscosity–temperature curves were all linear curves with two intersectional points. The viscosity of the sol with 11.8 wt% of L64 is 8.6 mPa s at the first intersectional point of 25 °C, which was suitable for coating membrane. The TG–DSC curves proved that the L64 was removed from the as-synthesized TiO2 upon calcination at 400 °C, which was chosen as the calcination temperature and the membrane could be obtained by dip-coating on a 19-channel ZrO2 support after five cycles of aging and calcining. The resulted multi-channel TiO2 membrane owing to a large specific surface area of 94.3 m2/g and a small anatase crystallite size of 9.0 nm, presented good ultrafiltration property. In dextran filtration experiments, its molecular weight cut-off was 5000 Da, which meant a crack-free multichannel TiO2 ultrafiltration membrane was successfully fabricated using this method.