以金红石二氧化钛为核、硅酸钠作为包覆剂,并流法制备核-壳结构TiO₂@SiO₂。采用单因素实验探究pH、温度、搅拌速率、包覆时间、二氧化钛初始浓度、包覆剂用量及陈化时间7个因素对产品酸溶率的影响,响应面实验优化制备工艺,用TEM、XPS、SEM、XRD、FT-IR、UV-vis等手段对产物进行表征。结果表明,固定搅拌速率为300 r/min、包覆时间为60 min、二氧化钛初始质量浓度为200 g/L,各因素对酸溶率的影响次序由大到小为：包覆剂用量、温度、pH、陈化时间,在较优工艺条件包覆剂用量为4.41%、温度为83.65 ℃、pH为9.59、陈化时间为25.62 h下,产物的酸溶率为3.43%。壳层为无定形二氧化硅、厚度约为5 nm左右的致密膜,以Ti—O—Si化学键合在二氧化钛核的表面,核-壳结构的TiO₂@SiO₂具有更高的紫外屏蔽能力。

Core-shell structure TiO₂@SiO₂ was prepared by parallel flow method using rutile TiO₂ as the core and sodium silicate as the coating agent.The influence of seven single factors including pH,temperature,stirring rate,coating time,initial concentration of TiO₂,coating amount and aging time on acid solubility of products were explored by single factor experiment.The preparation process was optimized by response surface experiment.The obtained product was characterized by TEM,XPS,SEM,XRD,FT-IR and UV-Vis.The results showed that when mixing rate was 300 r/min,the coating time was 60 min and the initial mass concentration of TiO₂ was 200 g/L,the order of influence of the four factors was as follows: coating dose> coating temperature>pH>aging time.The optimal conditions were as follows: the content of coating agent was 4.41%,the temperature was 83.65 ℃,the pH was 9.59 and the aging time was 25.62 h.Under the conditions,the acid solubility of the product reached 3.43%.The shell layer was amorphous SiO₂ with a thickness of about 5 nm and was chemically bonded on the surface of TiO₂ nucleus by Ti-O-Si.Core-shell structure TiO₂@SiO₂ has the higher UV shielding capability.