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 3.3nm 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 11.8wt% of L64 is 8.6mPas 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 94.3m²/g and a small anatase crystallite size of 9.0nm, presented good ultrafiltration property. In dextran filtration experiments, its molecular weight cut-off was 5000Da, which meant a crack-free multichannel TiO₂ ultrafiltration membrane was successfully fabricated using this method.