煅烧温度对TiO_2/硅藻土晶型结构与光催化性能的影响

Effect of Calcination Temperature on Crystal Structure and Photocatalytic Property of TiO_2/Diatomite Nanoparticles

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。

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 futile 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.