Abstract:

To address the disadvantage of suspended phase TiO₂ powder which is difficult to separate and recycle in the treatment of liquid pollutants and to further improve utilization of solar energy by TiO₂, Pr³⁺:Y₂SiO₅ powder, TiO₂ membrane and Pr³⁺:Y₂SiO₅/TiO₂composite membranes were prepared via the sol-gel method. XRD and SEM were used to characterize the properties of the samples. The relationship between efficiency of photocatalytic degradation of methylene blue by Pr³⁺:Y₂SiO₅/TiO₂ composite membrane and number of coating layers was investigated. Degradation rate could be as high as 96.43% with five coating layers of Pr³⁺:Y₂SiO₅/TiO₂ composite membrane, and the second and third degradation rates were 82.46% and 74.94%, respectively. With increasing area of Pr³⁺:Y₂SiO₅/TiO₂ composite membranes, degradation rate increased for a period of time then decreased finally. Degradation rate could be as high as 96.43% with eight coating layers of the membrane. Degradation rate would increase to 96.18% when illumination intensity reached 100 W. However, degradation rate decreased evidently with the increase of initial concentration of pollutions.

Key words: sol-gel method, upconversion material, composites, membranes, photocatalytic, degradation

摘要：

为解决悬浮相TiO₂粉体处理水中污染物后难以分离和回收利用的缺点并进一步提高纳米TiO₂对太阳光的利用率,采用溶胶-凝胶法制备了Pr³⁺:Y₂SiO₅粉体、TiO₂薄膜以及Pr³⁺:Y₂SiO₅/TiO₂复合膜。利用XRD、SEM等表征方法对样品进行表征。重点考察了Pr³⁺:Y₂SiO₅/TiO₂复合材料薄膜对亚甲基蓝的光催化降解效率与镀膜层数等因素的关系。结果发现涂覆5层Pr³⁺:Y₂SiO₅/TiO₂复合膜时,降解率可高达95.7%,其对应的第2次和第3次降解率分别为82.46%和74.94%;随着Pr³⁺:Y₂SiO₅/TiO₂复合膜薄膜面积的增加降解率先增加后降低,使用8张薄膜时降解率最高达96.43%;增加光照强度有利于提高降解率,但当光照强度增加到100 W时,降解率达到稳定值96.18%;随着初始浓度的增加,降解率逐渐降低。

关键词: 溶胶-凝胶法, 上转换材料, 复合材料, 薄膜, 光催化, 降解