超声辅助溶胶-凝胶法制备中空纤维TiO2超滤膜

TiO₂膜具有亲水性强和热化学稳定性好等优点而用于超滤分离, 但是TiO₂膜以管式膜为主, 渗透通量低且制备周期长。为了提高TiO₂膜的渗透通量, 并缩短膜的制备周期, 本工作以钛酸四丁酯为前驱体, 采用超声辅助溶胶-凝胶法制备高通量的中空纤维负载型TiO₂超滤膜。系统考察了硝酸与钛酸四丁酯的摩尔比(酸钛比)、超声时间和煅烧温度对TiO₂溶胶粒径及膜截留性能的影响。结果表明：当酸钛比为0.25时, 溶胶的平均粒径为3252 nm, 采用超声处理30 s后, 平均粒径减小至1817 nm。采用超声后的溶胶循环涂膜并在350 ℃煅烧两次后可得到完整无缺陷的中空纤维TiO₂超滤膜, 膜层平均厚度为1 μm, 膜的纯水渗透通量为145 L·m^-2·h^-1·bar^-1(1 bar=0.1 MPa), 葡聚糖截留分子量为2586 Da, 对应的平均孔径为2.5 nm。

Fabrication of Hollow Fiber Supported TiO2 Ultrafiltration Membranes via Ultrasound-assisted Sol-Gel Method

TiO₂ membranes have been applied in ultrafiltration (UF) separation due to their strong hydrophilicity and good thermochemical stability, but most of them are tubular membranes with low permeation flux and time-consuming preparation. To improve the flux and save the preparation time of TiO₂ membrane, hollow fiber supported TiO₂ UF membranes were prepared via ultrasound-assisted Sol-Gel method by using tetrabutyl titanate as precursor. Effects of acid/titanium molar ratio, ultrasound time and calcination temperature on TiO₂ sols and UF performance of membranes were investigated extensively. The results showed that when the acid/titanium ratio was 0.25, the obtained TiO₂ sol showed an average particle size of 3252 nm, which would be reduced to 1817 nm after ultrasonic treatment for 30 s. Coating with the above TiO₂ sol, defect-free TiO₂ UF membrane with average thickness of 1 μm can be prepared on hollow fiber support by calcining at 350 ℃ twice. The pure water flux of the obtained membrane was 145 L·m^-2·h^-1·bar^-1, and the dextran molecular weight at 90% rejection of membrane was 2586 Da with corresponding average pore size of 2.5 nm.