核-壳结构TiO2@Al2O3制备工艺的优化

Optimization of preparing process for pore-shell structure TiO2@Al2O3

探究温度、pH值、包覆量、包覆时间、初始质量浓度、搅拌速率、陈化时间等7个因素对并流法制备核-壳结构TiO2@Al2O3的酸溶率的影响;采用响应面实验优化制备工艺,并以高分辨透射电镜(HRTEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)、紫外-可见光谱(UV-vis)等表征产物,并测试其性能。结果表明:当TiO2初始质量浓度为200 g/L、搅拌速率为300 r/min、包覆时间为60 min时,各因素对酸溶率的影响次序为包覆量、温度、pH值、陈化时间;优化的工艺条件为:包覆量质量分数为4.5%、温度为83℃、pH=10、陈化时间为28 h,此时产物的酸溶率为17.4%;TiO2@Al2O3壳层的厚度约为6 nm,其组成为勃姆石型Al2O3,并且与TiO2核形成Ti-O-Al化学键,核-壳结构TiO2@Al2O3具有更好的水分散性、分散稳定性及紫外屏蔽能力。

The influence of seven single factors such as temperature,pH value,coating amount,initial concentration,stirring speed,coating time and aging time on acid solubility of core-shell structure TiO2@SiO2 over parallel flow method were investigated,and its preparation process was optimized by response surface experiment.The obtained product was characterized by HRTEM,XRD,XPS,SEM,and UV-Vis.The results show that when stirring speed is 300 r/min,the coating time is 60 min,and the initial concentration of TiO2 is 200 g/L,the order of influence of the four factors are coating dose,coating temperature,pH value and aging time.The acid solubility of the product reaches 17.4%under the optimal conditions such as 4.5%of content of coating agent,83℃of the temperature,10 of the pH value and 28 h of the aging time.The shell layer is a boehmite Al2O3 with a thickness of about 6 nm and is chemically bonded on the surface of TiO2 nucleus by Ti-O-Al.Core-shell structure of TiO2@Al2O3 has the higher water dispersibility,dispersive stability and UV shielding capability.