嵌段共聚物模板法制备La掺杂TiO2超滤膜

以钛酸四丁酯为Ti源, 氯化镧为La源, 采用嵌段共聚物模板法制备了La掺杂TiO₂超滤膜。通过动态热机械分析(DMA)、X射线衍射(XRD)、低温氮气吸附脱附和X射线光电子能谱(XPS)等表征方法, 考察了La掺杂对TiO₂凝胶的机械性能及其材料晶型、孔结构的影响。分析结果表明, La的引入显著提高了TiO₂凝胶的机械性能,避免了膜层在干燥阶段的开裂现象; 并有效抑制了晶粒增长和晶相转变, 使得锐钛矿相在800℃下仍能保持稳定。同时La的引入也提高了TiO₂材料的比表面积和孔隙率, 通过实验确定La掺杂量为0.74 g, 此时TiO₂溶胶的粒径分布最均一, 所得溶胶粒径为10 nm。采用该溶胶制备出的La-TiO₂超滤膜的孔径为2.3 nm, 而未掺杂时膜的孔径为2.7 nm。

Preparation of La-doped TiO2 Ultrafiltration Membrane by Templating of Block Copolymer

La-doped TiO₂ ultrafiltration membrane was prepared via a block copolymer assisted polymeric Sol-Gel process. The effects of La doping on the mechanical property of TiO₂ gel, the crystal phase transformation and mesostructure of TiO₂ materials were investigated by dynamic mechanical analysis (DMA), N₂ adsorption-desorption, X-ray diffraction (XRD), and X-ray photoelectron spectroscope (XPS) analysis. Results showed that the mechanical strength of the formed gel was significantly improved by the introduction of lanthanum, by which the risk of the membrane cracking could be reduced largely. X-ray diffraction analysis showed that La doping inhibited the TiO₂ crystal phase transformation and the anatase phase could still keep stable at 800℃. Furthermore, the BET surface area and porosity of the materials were also increased. The optimal La doping amount was 0.74 g, and the formed TiO₂ sol particle size was 10 nm. Futher more, the filtration experiments showed that the La-doped TiO₂ ultrafiltration membrane possessed a pore size of 2.3 nm, while the pore size of the La-undoped TiO₂ membrane was 2.7 nm.