煅烧温度对TiO2/硅藻土晶型结构与光催化性能的影响

以多孔非金属矿物硅藻土为载体, 钛酸四丁酯为前驱体, 采用溶胶–凝胶法制备TiO₂/硅藻土复合光催化材料。通过X射线衍射(XRD)、傅里叶红外光谱(FT-IR)、扫描电子显微镜(SEM)、紫外-可见分光光度计(UV-Vis spectroscopy)等方法对硅藻土及不同温度处理得到的复合样品的晶体结构、表面性能及形貌进行表征。结果表明: 载体硅藻土能够提高TiO₂的晶型转变温度, 并且使TiO₂纳米颗粒分散均匀, 有效抑制了团聚行为的发生。以10 mg/L的罗丹明B溶液为目标降解物, 250 W汞灯为光源, 研究不同热处理温度对TiO₂/硅藻土复合材料的光催化活性的影响。结果表明: 750℃煅烧2 h的样品光照120 min对罗丹明B的去除率接近100%, 与Degussa P25的去除率相当。此时样品中具有两种TiO₂晶型(A:R=9:1), 说明TiO₂的混晶效应能够有效地抑制光生电子-空穴复合, 使样品具有比单一锐钛矿型TiO₂更好的光催化性能。

Effect of Calcination Temperature on Crystal Structure and Photocatalytic Property of TiO2/Diatomite Nanoparticles

TiO₂/diatomite photocatalysts were synthesized by a facile Sol-Gel method using diatomite as supporter and tetrabutyl titanate (TBOT) as precursor. The crystalline and morphological properties of catalysts with different calcination temperatures were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and UV-Vis spectroscopy. Results reveal that the crystallite size becomes larger and the anatase phase transforms to the rutile phase at elevated temperature. Compared with unimmobilized TiO₂, the diatomite supporter impedes the transformation and prevents nano-TiO₂ particles from aggregation. The effect of calcination temperature on photocatalytic reactivities of these catalysts was investigated by UV-assisted degradation of 10 mg/L Rhodamine B (RhB). The sample calcined at 750℃ exhibits significantly enhanced reactivity with the removal rate of RhB up to about 100% after irradiation for 120 min, equivalent to that of Degussa P25 under similar conditions. The highest photocatalytic activity is observed in TiO₂/diatomite calcined under 750℃ which can be attributed to the presence of anatase and rutile phases in an appropriate ratio at 9:1.