用二氧化硅表面改性纳米二氧化钛的制备及表征

PREPARATION AND CHARACTERIZATION OF NANO-TITANIA SURFACE MODIFIED WITH SILICA

针对二氧化钛(TiO2)纳米颗粒在水性涂料中极易团聚、分散性差的问题,以提高 TiO2 分散稳定性为目的,用并流中和法,以锐钛矿型纳米TiO2 粉体为载体,硅酸钠(Na2SiO3)为包覆剂,用硫酸(H2SO4)调节 pH 值,成功地在纳米 TiO2 表面包覆致密的 SiO2 膜。借助 Fourier 变换红外光谱(Fourier transform infrared spectroscopy,FTIR)、X 射线衍射技术(X-ray diffraction, XRD)和 X 射线能量散射谱(X-ray energy dispersive spectroscopy, EDS),表征样品的键合情况、相态结构、表面的化学成分,同时测定包覆改性前后的纳米 TiO2比表面积和酸溶性。FTIR 和 EDS 结果表明:该包覆方法可行,氧化硅(SiO2)以化学键合的方式沉积在纳米 TiO2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。酸溶实验分析和 XRD 结果证实:在 TiO2纳米颗粒表面包覆了一层致密 SiO2膜。比表面测定的结果显示:改性后 TiO2的比表面积随质量分数 m(SiO2):m(TiO2)增加而减小。

In order to enhance the dispersion stability and reduce the agglomeration of titania （TiO2） nano-particles used in coatings, a compact silica film was successfully coated onto the surface of anatase TiO2 nano-particles by the simultaneous neutralization method, using sodium silicate as the coating agent and sulfuric acid as the neutralization agent. The surface bonding, phase constitution and chemical components of the coated samples were characterized by Fourier transform infrared spectroscopy （FTIR）, X-ray diffraction （XRD） and X-ray energy dispersive spectroscopy （EDS）. At the same time, the specific surface area and acidic solubility of TiO2 preand post-coating were compared. The EDS analysis and FTIR data illustrate that the silica film is deposited onto the surface of TiO2 through Ti-O-Si bonds, which formed at the interface of the coating layer and the surface of TiO2 particles. The compact silica film was also confirmed by the data of XRD and acidic solubility, and the specific surface area of silica-coated TiO2 nano-particles was found to decrease with the increase of m（SiO2）：m（TiO2）.