超声场中纳米TiO_2表面包覆氧化硅的研究

Study on Nanosized TiO_2 Coated by Silica in Ultrasonic Field

在超声场中,通过硅酸钠水解生成的无定形氧化硅对金红石相纳米TiO进行表面包覆,利用红外光谱、X射线光电子能2谱、X射线衍射和透射电镜对所得样品进行了表征,并对纳米TiO2的光稳定性和分散性进行了评价。红外光谱和X射线光电子能谱表明,氧化硅以化学键合的方式沉积在纳米TiO2的表面,在包覆层和纳米TiO2颗粒之间的界面上形成了Ti-O-Si键。TEM照片、表面元素分析和光稳定性实验显示,氧化硅在纳米TiO2表面形成了均匀的包覆层,超声场有助于提高包覆层的均匀性和致密性。氧化硅的表面包覆提高了纳米TiO2在水中的分散性、紫外线屏蔽能力和可见光透过性。随着氧化硅含量的增加,纳米TiO2的光稳定性逐渐提高,当m(SiO2)∶m(TiO2)>1∶5时,纳米TiO2的光稳定性基本不变,而且在热处理过程中纳米TiO2的晶粒生长得到有效抑制。

The nanosized TiO2 in the rutile phase was coated by amorphous silica in ultrasonic field using sodium silicate as raw material. The prepared samples were characterized by FTIR, XPS, TEM and XRD techniques. The photostability and dispersivity of nanosized TiO2 were also evaluated. According to the spectra of FTIR and XPS, it was inferred that the Ti-O-Si bond was formed at the interface of the coating layer and the surface of nanosized TiO2 particles. The TEM images, surface elemental analysis and photostability experiment showed that a uniform dense coating layer on the surface of nanosized TiO2 was produced, and that the homogeneity and densification of coating layer were improved from ultrasonic field treatment. The dispersivity, UV shielding property and transparency of nanosized TiO2 in water were enhanced due to the dense coating of silica. The increase of m(SiO2): m(TiO2) promoted the photostability of nanosized TiO2. But while the m(SiO2):m(TiO2) was higher than 1:5, the photostability was nearly unchanged, and the growth of the crystal grains was effectively suppressed in the process of heat treatment.