纳米TiO2的原位包覆及分散性研究

采用水热合成法制备纳米TiO2粉体，以自制的1100分散剂对粉体进行原位包覆和后包覆，考察了分散剂用量、pH值对包覆体系分散性的影响，利用XRD和TEM进行结构表征和形貌观测，并采用分光光度法对纳米TiO2粉体水分散体系稳定性进行了检测，在此基础上制备了纳米TiO2／有机复合涂膜．研究表明：原位包覆制备的纳米TiO2中，锐铁矿相的质量分数为100％，分散较均匀，纳米TiO2粉体的平均粒径约为20nm；分散剂用量为8．0％、pH值为3和10时，其水溶液分散稳定性较高；后包覆制备的纳米TiO2粉体由锐钛矿相（73％）和金红石相（27％）构成，纳米TiO2粒子处于团聚状态，无明显颗粒形态；涂膜经自然光照射24h后，对大肠杆菌的杀灭率为99．8％；良好的分散工艺和有效的分散剂可充分发挥纳米TiO2的光催化功能．

In-situ coating process and disperse property studies of nanometer titanium dioxide prepared by hydrothermal synthesis

Nanometer titanium dioxide powders were prepared by hydrothermal precipitating method,and was modified by in-situ and formed-powder coating techniques with self-prepared 1100 disperser to investigate the disperse property of system obtained.Crystal phase and grain size of the modified powders were studied by XRD and TEM.The stability of the dispersed aqueous of modified TiO_2 nanopowders was measured by spectrophotometer with different amount of 1100 disperser and different pH values.Furthermore,the composite film of TiO_2 nanopowders was prepared.Results indicated that nanometer titanium dioxide,modified by in-situ process,comprised pure anatase phase with highly disperse degree and with the size at about 20 nm.The highest disperse stability was obtained with 1100 disperser of 8.0% by weight and when pH at 3 or 10.The formed-coating powders comprised anatase phase(73%) and rutile phase(27%) with apparently accumulated state.The in-situ modified TiO_2exhibited well-dispersed state in composite film and highly catalytic activity even at sunlight wavelength.The bactericidal detection results showed that,after 24 h exposure of composite film in natural sunlight,99.8% of colibacillus could be killed.