负载TiO2的硅藻土对亚甲基蓝的光降解性能研究

硅藻土是一种天然生物成因的SiO₂. 采用硅藻土做载体,用溶胶-凝胶法制备TiO₂/硅藻土复合光催化剂,TiO₂呈薄膜状负载在硅藻土上,部分团聚成颗粒状. 在紫外光条件下负载TiO₂硅藻土对亚甲基蓝具有良好的光催化降解性能,36h后对亚甲基蓝的脱除率为90％, 48h达到98％, 降解效果好. 纯硅藻土48h后对亚甲基蓝的脱除率仅为35％左右. 负载TiO₂硅藻土对亚甲基蓝的光降解性能受TiO₂的同质多像结构影响. 随着锐钛矿含量增加, 负载TiO₂硅藻土的光降解性能增强. 但是, 当温度进一步升高, TiO₂由锐钛矿型转化为金红石型, 负载TiO₂硅藻土的光降解性能随之降低. 添加H₂O₂明显提高亚甲基蓝溶液的降解效果.

Photodecomposition of Methylene Blue by TiO2-mounted Diatomite

TiO₂-mounted diatomite photocatalysts were prepared by a sol-gel method with diatomite support, a kind of natural biological diatomaceous silica earth. SEM observation shows that TiO₂ is well mounted on the surface of diatomite as films and some particles. Ti ₂-mounted diatomite decomposes efficiently methy1ene blue (MB) under UV irradiation. Within 36h irradiation, about 90％ MB is decomposed by TiO₂/diatomite photocatalyst. After 48h irradiation, MB is decomposed almost completely (about 98％). However only 35％ MB is decomposed by pure diatomite after 48h irradiation. With the increasing heat-treatment temperatures, the photocatalytic activity of the TiO₂/diatomite is increased with the formed anatase type of TiO₂ increasing, but decreased with rutile type of TiO₂ formed at 700℃ and 900℃. Adding H₂O₂ in MB solution can improve the efficiency of the TiO₂-mounted diatomite photocatalysts greatly.