以球形氧化铝为载体, 采用溶胶-凝胶法和浸渍涂覆过程制备了负载型二氧化钛光催化材料。 以扫描电子显微镜(SEM)和X-射线衍射仪(XRD)等手段对所合成的样品形貌及晶型进行了表征。 结果表明, 氧化铝载体经负载二氧化钛后, 在球形氧化铝表面沉积了一层粒径为10～20 nm的锐钛型二氧化钛纳米颗粒。 通过能量色散X射线光谱(EDX)对氧化铝载体和所合成的样品进行进一步分析, 表明样品中明显存在Ti元素。 另外, 提高氧化铝载体在二氧化钛溶胶中的浸渍次数能够有效提高二氧化钛的负载量。 当浸渍次数增加到5次时, Ti元素的含量由3.8 Wt.%提高至15.7 Wt.%。 另外, 以亚甲基蓝为目标降解物, 详细研究了不同浸渍次数获得的负载型二氧化钛催化材料的催化性能。 结果表明: 随着浸渍次数的增加, 负载型二氧化钛催化材料的表面形貌不仅得到明显改善, 而且显著提高了样品的光催化活性。 当浸渍次数由1次提高至4次时, 亚甲基蓝的降解率由40%上升至83.1%。 然而, 当二氧化钛负载量达到一定程度时, 由于不断浸渍导致下层的二氧化钛受光照机会和光照强度减弱, 导致其光催化活性提高缓慢。 当浸渍次数提高至5次时, 亚甲基蓝降解率仅为85.6%。 所制备的负载型二氧化钛光催化材料重复使用5次, 其光催化活性保持相对稳定。

Titanium dioxide (TiO2) supported on spherical alumina substrate was prepared by using sol-gel method combined with dip-coating process. The surface morphology and structure of the synthesized samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) pattern. The results show that the morphology of the supported TiO2 composite material was obviously different from that of the original support. It reveals a layer formed by anatase TiO2 nanoparticles of 10～20 nm was deposited on the alumina substrate. Energy dispersive X-ray spectroscopy (EDX) analyses on the spherical alumina substrate and the resulting TiO2 composite catalyst were performed to determine the TiO2 loading content in the samples. It indicates that the TiO2 loading content on alumina substrate could be effectively increased by increasing the times of dip-coating alumina support in TiO2 sol. When dip-coating times increased to 5, the TiO2 loading content increased from 3.8 Wt.% to 15.7 Wt.%. In addition, the photocatalytic performances of the supported TiO2 materials prepared by different dip-coating times have been investigated by degrading methylene blue. It was found that the surface morphology of the supported TiO2 material was not only improved, but also the photocatalytic activity could be promoted significantly by increasing the dip-coating times. When the alumina substrate was dip-coated in TiO2 sol from 1 to 4 times, the degradation rate of methylene blue increased from 40% to 83.1%. However, after dip-coating the alumina support in TiO2 sol for 5 times, the degradation of methylene blue was only up to 85.6%. This indicates that the photocatalytic activity increased slowly when the TiO2 content in the supported catalyst was up to some extent. It is attributed to the continuous dip-coating resulted in less opportunities and weak intensity of illumination for the TiO2 nano-particles that under lower layer. The photocatalytic activity was relatively stable after repeated use of the supported TiO2 material for 5 times.